third_party/angle/src/tests/gl_tests/StateChangeTest.cpp

//
// Copyright 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// StateChangeTest:
//   Specifically designed for an ANGLE implementation of GL, these tests validate that
//   ANGLE's dirty bits systems don't get confused by certain sequences of state changes.
//

#include "test_utils/ANGLETest.h"
#include "test_utils/gl_raii.h"

using namespace angle;

namespace
{

class StateChangeTest : public ANGLETest
{
  protected:
    StateChangeTest()
    {
        setWindowWidth(64);
        setWindowHeight(64);
        setConfigRedBits(8);
        setConfigGreenBits(8);
        setConfigBlueBits(8);
        setConfigAlphaBits(8);

        // Enable the no error extension to avoid syncing the FBO state on validation.
        setNoErrorEnabled(true);
    }

    void testSetUp() override
    {
        glGenFramebuffers(1, &mFramebuffer);
        glGenTextures(2, mTextures.data());
        glGenRenderbuffers(1, &mRenderbuffer);

        ASSERT_GL_NO_ERROR();
    }

    void testTearDown() override
    {
        if (mFramebuffer != 0)
        {
            glDeleteFramebuffers(1, &mFramebuffer);
            mFramebuffer = 0;
        }

        if (!mTextures.empty())
        {
            glDeleteTextures(static_cast<GLsizei>(mTextures.size()), mTextures.data());
            mTextures.clear();
        }

        glDeleteRenderbuffers(1, &mRenderbuffer);
    }

    GLuint mFramebuffer           = 0;
    GLuint mRenderbuffer          = 0;
    std::vector<GLuint> mTextures = {0, 0};
};

class StateChangeTestES3 : public StateChangeTest
{
  protected:
    StateChangeTestES3() {}
};

// Ensure that CopyTexImage2D syncs framebuffer changes.
TEST_P(StateChangeTest, CopyTexImage2DSync)
{
    // TODO(geofflang): Fix on Linux AMD drivers (http://anglebug.com/1291)
    ANGLE_SKIP_TEST_IF(IsAMD() && IsOpenGL());

    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    // Init first texture to red
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    // Init second texture to green
    glBindTexture(GL_TEXTURE_2D, mTextures[1]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[1], 0);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 0, 255, 0, 255);

    // Copy in the red texture to the green one.
    // CopyTexImage should sync the framebuffer attachment change.
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 0, 0, 16, 16, 0);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[1], 0);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    ASSERT_GL_NO_ERROR();
}

// Ensure that CopyTexSubImage2D syncs framebuffer changes.
TEST_P(StateChangeTest, CopyTexSubImage2DSync)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    // Init first texture to red
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    // Init second texture to green
    glBindTexture(GL_TEXTURE_2D, mTextures[1]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[1], 0);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 0, 255, 0, 255);

    // Copy in the red texture to the green one.
    // CopyTexImage should sync the framebuffer attachment change.
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 16, 16);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[1], 0);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    ASSERT_GL_NO_ERROR();
}

// Test that Framebuffer completeness caching works when color attachments change.
TEST_P(StateChangeTest, FramebufferIncompleteColorAttachment)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture at color attachment 0 to be non-color-renderable.
    glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, 16, 16, 0, GL_ALPHA, GL_UNSIGNED_BYTE, nullptr);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that caching works when color attachments change with TexStorage.
TEST_P(StateChangeTest, FramebufferIncompleteWithTexStorage)
{
    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_texture_storage"));

    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture at color attachment 0 to be non-color-renderable.
    glTexStorage2DEXT(GL_TEXTURE_2D, 1, GL_ALPHA8_EXT, 16, 16);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that caching works when color attachments change with CompressedTexImage2D.
TEST_P(StateChangeTestES3, FramebufferIncompleteWithCompressedTex)
{
    // ETC texture formats are not supported on Mac OpenGL. http://anglebug.com/3853
    ANGLE_SKIP_TEST_IF(IsOSX() && IsDesktopOpenGL());

    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture at color attachment 0 to be non-color-renderable.
    glCompressedTexImage2D(GL_TEXTURE_2D, 0, GL_COMPRESSED_RGB8_ETC2, 16, 16, 0, 128, nullptr);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that caching works when color attachments are deleted.
TEST_P(StateChangeTestES3, FramebufferIncompleteWhenAttachmentDeleted)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Delete the texture at color attachment 0.
    glDeleteTextures(1, &mTextures[0]);
    mTextures[0] = 0;
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that Framebuffer completeness caching works when depth attachments change.
TEST_P(StateChangeTest, FramebufferIncompleteDepthAttachment)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glBindRenderbuffer(GL_RENDERBUFFER, mRenderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT16, 16, 16);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, mRenderbuffer);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture at color attachment 0 to be non-depth-renderable.
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 16, 16);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that Framebuffer completeness caching works when stencil attachments change.
TEST_P(StateChangeTest, FramebufferIncompleteStencilAttachment)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glBindRenderbuffer(GL_RENDERBUFFER, mRenderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_STENCIL_INDEX8, 16, 16);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
                              mRenderbuffer);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture at the stencil attachment to be non-stencil-renderable.
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 16, 16);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

// Test that Framebuffer completeness caching works when depth-stencil attachments change.
TEST_P(StateChangeTest, FramebufferIncompleteDepthStencilAttachment)
{
    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3 &&
                       !IsGLExtensionEnabled("GL_OES_packed_depth_stencil"));

    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glBindRenderbuffer(GL_RENDERBUFFER, mRenderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 16, 16);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER,
                              mRenderbuffer);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Change the texture the depth-stencil attachment to be non-depth-stencil-renderable.
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 16, 16);
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ASSERT_GL_NO_ERROR();
}

const char kSimpleAttributeVS[] = R"(attribute vec2 position;
attribute vec4 testAttrib;
varying vec4 testVarying;
void main()
{
    gl_Position = vec4(position, 0, 1);
    testVarying = testAttrib;
})";

const char kSimpleAttributeFS[] = R"(precision mediump float;
varying vec4 testVarying;
void main()
{
    gl_FragColor = testVarying;
})";

// Tests that using a buffered attribute, then disabling it and using current value, works.
TEST_P(StateChangeTest, DisablingBufferedVertexAttribute)
{
    ANGLE_GL_PROGRAM(program, kSimpleAttributeVS, kSimpleAttributeFS);
    glUseProgram(program);
    GLint attribLoc   = glGetAttribLocation(program, "testAttrib");
    GLint positionLoc = glGetAttribLocation(program, "position");
    ASSERT_NE(-1, attribLoc);
    ASSERT_NE(-1, positionLoc);

    // Set up the buffered attribute.
    std::vector<GLColor> red(6, GLColor::red);
    GLBuffer attribBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, attribBuffer);
    glBufferData(GL_ARRAY_BUFFER, red.size() * sizeof(GLColor), red.data(), GL_STATIC_DRAW);
    glEnableVertexAttribArray(attribLoc);
    glVertexAttribPointer(attribLoc, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);

    // Also set the current value to green now.
    glVertexAttrib4f(attribLoc, 0.0f, 1.0f, 0.0f, 1.0f);

    // Set up the position attribute as well.
    setupQuadVertexBuffer(0.5f, 1.0f);
    glEnableVertexAttribArray(positionLoc);
    glVertexAttribPointer(positionLoc, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    // Draw with the buffered attribute. Verify red.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Draw with the disabled "current value attribute". Verify green.
    glDisableVertexAttribArray(attribLoc);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Verify setting buffer data on the disabled buffer doesn't change anything.
    std::vector<GLColor> blue(128, GLColor::blue);
    glBindBuffer(GL_ARRAY_BUFFER, attribBuffer);
    glBufferData(GL_ARRAY_BUFFER, blue.size() * sizeof(GLColor), blue.data(), GL_STATIC_DRAW);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
}

// Tests that setting value for a subset of default attributes doesn't affect others.
TEST_P(StateChangeTest, SetCurrentAttribute)
{
    constexpr char kVS[] = R"(attribute vec4 position;
attribute mat4 testAttrib;  // Note that this generates 4 attributes
varying vec4 testVarying;
void main (void)
{
    gl_Position = position;

    testVarying = position.y < 0.0 ?
                    position.x < 0.0 ? testAttrib[0] : testAttrib[1] :
                    position.x < 0.0 ? testAttrib[2] : testAttrib[3];
})";

    ANGLE_GL_PROGRAM(program, kVS, kSimpleAttributeFS);
    glUseProgram(program);
    GLint attribLoc   = glGetAttribLocation(program, "testAttrib");
    GLint positionLoc = glGetAttribLocation(program, "position");
    ASSERT_NE(-1, attribLoc);
    ASSERT_NE(-1, positionLoc);

    // Set the current value of two of the test attributes, while leaving the other two as default.
    glVertexAttrib4f(attribLoc + 1, 0.0f, 1.0f, 0.0f, 1.0f);
    glVertexAttrib4f(attribLoc + 2, 0.0f, 0.0f, 1.0f, 1.0f);

    // Set up the position attribute.
    setupQuadVertexBuffer(0.5f, 1.0f);
    glEnableVertexAttribArray(positionLoc);
    glVertexAttribPointer(positionLoc, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    // Draw and verify the four section in the output:
    //
    //  +---------------+
    //  | Black | Green |
    //  +-------+-------+
    //  | Blue  | Black |
    //  +---------------+
    //
    glDrawArrays(GL_TRIANGLES, 0, 6);

    const int w                            = getWindowWidth();
    const int h                            = getWindowHeight();
    constexpr unsigned int kPixelTolerance = 5u;
    EXPECT_PIXEL_COLOR_NEAR(0, 0, GLColor::black, kPixelTolerance);
    EXPECT_PIXEL_COLOR_NEAR(w - 1, 0, GLColor::green, kPixelTolerance);
    EXPECT_PIXEL_COLOR_NEAR(0, h - 1, GLColor::blue, kPixelTolerance);
    EXPECT_PIXEL_COLOR_NEAR(w - 1, h - 1, GLColor::black, kPixelTolerance);
}

// Tests that vertex attribute value is preserved across context switches.
TEST_P(StateChangeTest, MultiContextVertexAttribute)
{
    EGLWindow *window   = getEGLWindow();
    EGLDisplay display  = window->getDisplay();
    EGLConfig config    = window->getConfig();
    EGLSurface surface  = window->getSurface();
    EGLContext context1 = window->getContext();

    // Set up program in primary context
    ANGLE_GL_PROGRAM(program1, kSimpleAttributeVS, kSimpleAttributeFS);
    glUseProgram(program1);
    GLint attribLoc   = glGetAttribLocation(program1, "testAttrib");
    GLint positionLoc = glGetAttribLocation(program1, "position");
    ASSERT_NE(-1, attribLoc);
    ASSERT_NE(-1, positionLoc);

    // Set up the position attribute in primary context
    setupQuadVertexBuffer(0.5f, 1.0f);
    glEnableVertexAttribArray(positionLoc);
    glVertexAttribPointer(positionLoc, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    // Set primary context attribute to green and draw quad
    glVertexAttrib4f(attribLoc, 0.0f, 1.0f, 0.0f, 1.0f);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Set up and switch to secondary context
    EGLint contextAttributes[] = {
        EGL_CONTEXT_MAJOR_VERSION_KHR,
        GetParam().majorVersion,
        EGL_CONTEXT_MINOR_VERSION_KHR,
        GetParam().minorVersion,
        EGL_NONE,
    };
    EGLContext context2 = eglCreateContext(display, config, EGL_NO_CONTEXT, contextAttributes);
    ASSERT_NE(context2, EGL_NO_CONTEXT);
    eglMakeCurrent(display, surface, surface, context2);

    // Set up program in secondary context
    ANGLE_GL_PROGRAM(program2, kSimpleAttributeVS, kSimpleAttributeFS);
    glUseProgram(program2);
    ASSERT_EQ(attribLoc, glGetAttribLocation(program2, "testAttrib"));
    ASSERT_EQ(positionLoc, glGetAttribLocation(program2, "position"));

    // Set up the position attribute in secondary context
    setupQuadVertexBuffer(0.5f, 1.0f);
    glEnableVertexAttribArray(positionLoc);
    glVertexAttribPointer(positionLoc, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    // attribLoc current value should be default - (0,0,0,1)
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::black);

    // Restore primary context
    eglMakeCurrent(display, surface, surface, context1);
    // ReadPixels to ensure context is switched
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::black);

    // Switch to secondary context second time
    eglMakeCurrent(display, surface, surface, context2);
    // Check that it still draws black
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::black);

    // Restore primary context second time
    eglMakeCurrent(display, surface, surface, context1);
    // Check if it still draws green
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Clean up
    eglDestroyContext(display, context2);
}

// Ensure that CopyTexSubImage3D syncs framebuffer changes.
TEST_P(StateChangeTestES3, CopyTexSubImage3DSync)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    // Init first texture to red
    glBindTexture(GL_TEXTURE_3D, mTextures[0]);
    glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA, 16, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, mTextures[0], 0, 0);
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    // Init second texture to green
    glBindTexture(GL_TEXTURE_3D, mTextures[1]);
    glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA, 16, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, mTextures[1], 0, 0);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 0, 255, 0, 255);

    // Copy in the red texture to the green one.
    // CopyTexImage should sync the framebuffer attachment change.
    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, mTextures[0], 0, 0);
    glCopyTexSubImage3D(GL_TEXTURE_3D, 0, 0, 0, 0, 0, 0, 16, 16);
    glFramebufferTextureLayer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, mTextures[1], 0, 0);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    ASSERT_GL_NO_ERROR();
}

// Ensure that BlitFramebuffer syncs framebuffer changes.
TEST_P(StateChangeTestES3, BlitFramebufferSync)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsVulkan());
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    // Init first texture to red
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    // Init second texture to green
    glBindTexture(GL_TEXTURE_2D, mTextures[1]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[1], 0);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    EXPECT_PIXEL_EQ(0, 0, 0, 255, 0, 255);

    // Change to the red textures and blit.
    // BlitFramebuffer should sync the framebuffer attachment change.
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
    glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0],
                           0);
    glBlitFramebuffer(0, 0, 16, 16, 0, 0, 16, 16, GL_COLOR_BUFFER_BIT, GL_NEAREST);
    glBindFramebuffer(GL_READ_FRAMEBUFFER, 0);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    ASSERT_GL_NO_ERROR();
}

// Ensure that ReadBuffer and DrawBuffers sync framebuffer changes.
TEST_P(StateChangeTestES3, ReadBufferAndDrawBuffersSync)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    // Initialize two FBO attachments
    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);
    glBindTexture(GL_TEXTURE_2D, mTextures[1]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT1, GL_TEXTURE_2D, mTextures[1], 0);

    // Clear first attachment to red
    GLenum bufs1[] = {GL_COLOR_ATTACHMENT0, GL_NONE};
    glDrawBuffers(2, bufs1);
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Clear second texture to green
    GLenum bufs2[] = {GL_NONE, GL_COLOR_ATTACHMENT1};
    glDrawBuffers(2, bufs2);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Verify first attachment is red and second is green
    glReadBuffer(GL_COLOR_ATTACHMENT1);
    EXPECT_PIXEL_EQ(0, 0, 0, 255, 0, 255);

    glReadBuffer(GL_COLOR_ATTACHMENT0);
    EXPECT_PIXEL_EQ(0, 0, 255, 0, 0, 255);

    ASSERT_GL_NO_ERROR();
}

// Tests calling invalidate on incomplete framebuffers after switching attachments.
// Adapted partially from WebGL 2 test "renderbuffers/invalidate-framebuffer"
TEST_P(StateChangeTestES3, IncompleteRenderbufferAttachmentInvalidateSync)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsVulkan());
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);
    glBindRenderbuffer(GL_RENDERBUFFER, mRenderbuffer);
    GLint samples = 0;
    glGetInternalformativ(GL_RENDERBUFFER, GL_RGBA8, GL_SAMPLES, 1, &samples);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, mRenderbuffer);
    ASSERT_GL_NO_ERROR();

    // invalidate the framebuffer when the attachment is incomplete: no storage allocated to the
    // attached renderbuffer
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT,
                     glCheckFramebufferStatus(GL_FRAMEBUFFER));
    GLenum attachments1[] = {GL_COLOR_ATTACHMENT0};
    glInvalidateFramebuffer(GL_FRAMEBUFFER, 1, attachments1);
    ASSERT_GL_NO_ERROR();

    glRenderbufferStorageMultisample(GL_RENDERBUFFER, static_cast<GLsizei>(samples), GL_RGBA8,
                                     getWindowWidth(), getWindowHeight());
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
    glClear(GL_COLOR_BUFFER_BIT);
    ASSERT_GL_NO_ERROR();

    GLRenderbuffer renderbuf;

    glBindRenderbuffer(GL_RENDERBUFFER, renderbuf.get());
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER,
                              renderbuf.get());
    ASSERT_GL_NO_ERROR();

    // invalidate the framebuffer when the attachment is incomplete: no storage allocated to the
    // attached renderbuffer
    // Note: the bug will only repro *without* a call to checkStatus before the invalidate.
    GLenum attachments2[] = {GL_DEPTH_ATTACHMENT};
    glInvalidateFramebuffer(GL_FRAMEBUFFER, 1, attachments2);

    glRenderbufferStorageMultisample(GL_RENDERBUFFER, static_cast<GLsizei>(samples),
                                     GL_DEPTH_COMPONENT16, getWindowWidth(), getWindowHeight());
    EXPECT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));
    glClear(GL_DEPTH_BUFFER_BIT);
    ASSERT_GL_NO_ERROR();
}

class StateChangeRenderTest : public StateChangeTest
{
  protected:
    StateChangeRenderTest() : mProgram(0), mRenderbuffer(0) {}

    void testSetUp() override
    {
        StateChangeTest::testSetUp();

        constexpr char kVS[] =
            "attribute vec2 position;\n"
            "void main() {\n"
            "    gl_Position = vec4(position, 0, 1);\n"
            "}";
        constexpr char kFS[] =
            "uniform highp vec4 uniformColor;\n"
            "void main() {\n"
            "    gl_FragColor = uniformColor;\n"
            "}";

        mProgram = CompileProgram(kVS, kFS);
        ASSERT_NE(0u, mProgram);

        glGenRenderbuffers(1, &mRenderbuffer);
    }

    void testTearDown() override
    {
        glDeleteProgram(mProgram);
        glDeleteRenderbuffers(1, &mRenderbuffer);

        StateChangeTest::testTearDown();
    }

    void setUniformColor(const GLColor &color)
    {
        glUseProgram(mProgram);
        const Vector4 &normalizedColor = color.toNormalizedVector();
        GLint uniformLocation          = glGetUniformLocation(mProgram, "uniformColor");
        ASSERT_NE(-1, uniformLocation);
        glUniform4fv(uniformLocation, 1, normalizedColor.data());
    }

    GLuint mProgram;
    GLuint mRenderbuffer;
};

// Test that re-creating a currently attached texture works as expected.
TEST_P(StateChangeRenderTest, RecreateTexture)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Draw with red to the FBO.
    GLColor red(255, 0, 0, 255);
    setUniformColor(red);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, red);

    // Recreate the texture with green.
    GLColor green(0, 255, 0, 255);
    std::vector<GLColor> greenPixels(32 * 32, green);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE,
                 greenPixels.data());
    EXPECT_PIXEL_COLOR_EQ(0, 0, green);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Verify drawing blue gives blue. This covers the FBO sync with D3D dirty bits.
    GLColor blue(0, 0, 255, 255);
    setUniformColor(blue);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, blue);

    EXPECT_GL_NO_ERROR();
}

// Test that re-creating a currently attached renderbuffer works as expected.
TEST_P(StateChangeRenderTest, RecreateRenderbuffer)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    glBindRenderbuffer(GL_RENDERBUFFER, mRenderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 16, 16);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, mRenderbuffer);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Draw with red to the FBO.
    GLColor red(255, 0, 0, 255);
    setUniformColor(red);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, red);

    // Recreate the renderbuffer and clear to green.
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 32, 32);
    glClearColor(0.0f, 1.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    GLColor green(0, 255, 0, 255);
    EXPECT_PIXEL_COLOR_EQ(0, 0, green);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Verify drawing blue gives blue. This covers the FBO sync with D3D dirty bits.
    GLColor blue(0, 0, 255, 255);
    setUniformColor(blue);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, blue);

    EXPECT_GL_NO_ERROR();
}

// Test that recreating a texture with GenerateMipmaps signals the FBO is dirty.
TEST_P(StateChangeRenderTest, GenerateMipmap)
{
    glBindFramebuffer(GL_FRAMEBUFFER, mFramebuffer);

    glBindTexture(GL_TEXTURE_2D, mTextures[0]);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 16, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glTexImage2D(GL_TEXTURE_2D, 1, GL_RGBA, 8, 8, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glTexImage2D(GL_TEXTURE_2D, 2, GL_RGBA, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTextures[0], 0);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Draw once to set the RenderTarget in D3D11
    GLColor red(255, 0, 0, 255);
    setUniformColor(red);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, red);

    // This will trigger the texture to be re-created on FL9_3.
    glGenerateMipmap(GL_TEXTURE_2D);

    // Explictly check FBO status sync in some versions of ANGLE no_error skips FBO checks.
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Now ensure we don't have a stale render target.
    GLColor blue(0, 0, 255, 255);
    setUniformColor(blue);
    drawQuad(mProgram, "position", 0.5f);
    EXPECT_PIXEL_COLOR_EQ(0, 0, blue);

    EXPECT_GL_NO_ERROR();
}

// Tests that gl_DepthRange syncs correctly after a change.
TEST_P(StateChangeRenderTest, DepthRangeUpdates)
{
    // http://anglebug.com/2598: Seems to be an Intel driver bug.
    ANGLE_SKIP_TEST_IF(IsIntel() && IsOpenGL() && IsWindows());

    constexpr char kFragCoordShader[] = R"(void main()
{
    if (gl_DepthRange.near == 0.2)
    {
        gl_FragColor = vec4(1, 0, 0, 1);
    }
    else if (gl_DepthRange.near == 0.5)
    {
        gl_FragColor = vec4(0, 1, 0, 1);
    }
    else
    {
        gl_FragColor = vec4(0, 0, 1, 1);
    }
})";

    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), kFragCoordShader);
    glUseProgram(program);

    const auto &quadVertices = GetQuadVertices();

    ASSERT_EQ(0, glGetAttribLocation(program, essl1_shaders::PositionAttrib()));

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, quadVertices.size() * sizeof(quadVertices[0]),
                 quadVertices.data(), GL_STATIC_DRAW);
    glVertexAttribPointer(0u, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(0u);

    // First, clear.
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Draw to left half viewport with a first depth range.
    glDepthRangef(0.2f, 1.0f);
    glViewport(0, 0, getWindowWidth() / 2, getWindowHeight());
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Draw to right half viewport with a second depth range.
    glDepthRangef(0.5f, 1.0f);
    glViewport(getWindowWidth() / 2, 0, getWindowWidth() / 2, getWindowHeight());
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Verify left half of the framebuffer is red and right half is green.
    EXPECT_PIXEL_RECT_EQ(0, 0, getWindowWidth() / 2, getWindowHeight(), GLColor::red);
    EXPECT_PIXEL_RECT_EQ(getWindowWidth() / 2, 0, getWindowWidth() / 2, getWindowHeight(),
                         GLColor::green);
}

// Tests that D3D11 dirty bit updates don't forget about BufferSubData attrib updates.
TEST_P(StateChangeTest, VertexBufferUpdatedAfterDraw)
{
    // TODO(jie.a.chen@intel.com): Re-enable the test once the driver fix is
    // available in public release.
    // http://anglebug.com/2664.
    ANGLE_SKIP_TEST_IF(IsVulkan() && IsIntel());

    constexpr char kVS[] =
        "attribute vec2 position;\n"
        "attribute vec4 color;\n"
        "varying vec4 outcolor;\n"
        "void main()\n"
        "{\n"
        "    gl_Position = vec4(position, 0, 1);\n"
        "    outcolor = color;\n"
        "}";
    constexpr char kFS[] =
        "varying mediump vec4 outcolor;\n"
        "void main()\n"
        "{\n"
        "    gl_FragColor = outcolor;\n"
        "}";

    ANGLE_GL_PROGRAM(program, kVS, kFS);
    glUseProgram(program);

    GLint colorLoc = glGetAttribLocation(program, "color");
    ASSERT_NE(-1, colorLoc);
    GLint positionLoc = glGetAttribLocation(program, "position");
    ASSERT_NE(-1, positionLoc);

    setupQuadVertexBuffer(0.5f, 1.0f);
    glEnableVertexAttribArray(positionLoc);
    glVertexAttribPointer(positionLoc, 3, GL_FLOAT, GL_FALSE, 0, nullptr);

    GLBuffer colorBuf;
    glBindBuffer(GL_ARRAY_BUFFER, colorBuf);
    glVertexAttribPointer(colorLoc, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);
    glEnableVertexAttribArray(colorLoc);

    // Fill with green.
    std::vector<GLColor> colorData(6, GLColor::green);
    glBufferData(GL_ARRAY_BUFFER, colorData.size() * sizeof(GLColor), colorData.data(),
                 GL_STATIC_DRAW);

    // Draw, expect green.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
    ASSERT_GL_NO_ERROR();

    // Update buffer with red.
    std::fill(colorData.begin(), colorData.end(), GLColor::red);
    glBufferSubData(GL_ARRAY_BUFFER, 0, colorData.size() * sizeof(GLColor), colorData.data());

    // Draw, expect red.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    ASSERT_GL_NO_ERROR();
}

// Test that switching VAOs keeps the disabled "current value" attributes up-to-date.
TEST_P(StateChangeTestES3, VertexArrayObjectAndDisabledAttributes)
{
    constexpr char kSingleVS[] = "attribute vec4 position; void main() { gl_Position = position; }";
    constexpr char kSingleFS[] = "void main() { gl_FragColor = vec4(1, 0, 0, 1); }";
    ANGLE_GL_PROGRAM(singleProgram, kSingleVS, kSingleFS);

    constexpr char kDualVS[] =
        "#version 300 es\n"
        "in vec4 position;\n"
        "in vec4 color;\n"
        "out vec4 varyColor;\n"
        "void main()\n"
        "{\n"
        "    gl_Position = position;\n"
        "    varyColor = color;\n"
        "}";
    constexpr char kDualFS[] =
        "#version 300 es\n"
        "precision mediump float;\n"
        "in vec4 varyColor;\n"
        "out vec4 colorOut;\n"
        "void main()\n"
        "{\n"
        "    colorOut = varyColor;\n"
        "}";

    ANGLE_GL_PROGRAM(dualProgram, kDualVS, kDualFS);

    // Force consistent attribute locations
    constexpr GLint positionLocation = 0;
    constexpr GLint colorLocation    = 1;

    glBindAttribLocation(singleProgram, positionLocation, "position");
    glBindAttribLocation(dualProgram, positionLocation, "position");
    glBindAttribLocation(dualProgram, colorLocation, "color");

    {
        glLinkProgram(singleProgram);
        GLint linkStatus;
        glGetProgramiv(singleProgram, GL_LINK_STATUS, &linkStatus);
        ASSERT_NE(linkStatus, 0);
    }

    {
        glLinkProgram(dualProgram);
        GLint linkStatus;
        glGetProgramiv(dualProgram, GL_LINK_STATUS, &linkStatus);
        ASSERT_NE(linkStatus, 0);
    }

    glUseProgram(singleProgram);

    // Initialize position vertex buffer.
    const auto &quadVertices = GetQuadVertices();

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(Vector3) * 6, quadVertices.data(), GL_STATIC_DRAW);

    // Initialize a VAO. Draw with single program.
    GLVertexArray vertexArray;
    glBindVertexArray(vertexArray);
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    // Should draw red.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Draw with a green buffer attribute, without the VAO.
    glBindVertexArray(0);
    glUseProgram(dualProgram);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    std::vector<GLColor> greenColors(6, GLColor::green);
    GLBuffer greenBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, greenBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLColor) * 6, greenColors.data(), GL_STATIC_DRAW);

    glVertexAttribPointer(colorLocation, 4, GL_UNSIGNED_BYTE, GL_FALSE, 4, nullptr);
    glEnableVertexAttribArray(colorLocation);

    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Re-bind VAO and try to draw with different program, without changing state.
    // Should draw black since current value is not initialized.
    glBindVertexArray(vertexArray);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::black);
}

const char kSamplerMetadataVertexShader0[] = R"(#version 300 es
precision mediump float;
out vec4 color;
uniform sampler2D texture;
void main()
{
    vec2 size = vec2(textureSize(texture, 0));
    color = size.x != 0.0 ? vec4(0.0, 1.0, 0.0, 1.0) : vec4(1.0, 0.0, 0.0, 0.0);
    vec2 pos = vec2(0.0);
    switch (gl_VertexID) {
        case 0: pos = vec2(-1.0, -1.0); break;
        case 1: pos = vec2(3.0, -1.0); break;
        case 2: pos = vec2(-1.0, 3.0); break;
    };
    gl_Position = vec4(pos, 0.0, 1.0);
})";

const char kSamplerMetadataVertexShader1[] = R"(#version 300 es
precision mediump float;
out vec4 color;
uniform sampler2D texture1;
uniform sampler2D texture2;
void main()
{
    vec2 size1 = vec2(textureSize(texture1, 0));
    vec2 size2 = vec2(textureSize(texture2, 0));
    color = size1.x * size2.x != 0.0 ? vec4(0.0, 1.0, 0.0, 1.0) : vec4(1.0, 0.0, 0.0, 0.0);
    vec2 pos = vec2(0.0);
    switch (gl_VertexID) {
        case 0: pos = vec2(-1.0, -1.0); break;
        case 1: pos = vec2(3.0, -1.0); break;
        case 2: pos = vec2(-1.0, 3.0); break;
    };
    gl_Position = vec4(pos, 0.0, 1.0);
})";

const char kSamplerMetadataFragmentShader[] = R"(#version 300 es
precision mediump float;
in vec4 color;
out vec4 result;
void main()
{
    result = color;
})";

// Tests that changing an active program invalidates the sampler metadata properly.
TEST_P(StateChangeTestES3, SamplerMetadataUpdateOnSetProgram)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsAndroid() && IsOpenGLES());
    GLVertexArray vertexArray;
    glBindVertexArray(vertexArray);

    // Create a simple framebuffer.
    GLTexture texture1, texture2;
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, texture2);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 3, 3, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    // Create 2 shader programs differing only in the number of active samplers.
    ANGLE_GL_PROGRAM(program1, kSamplerMetadataVertexShader0, kSamplerMetadataFragmentShader);
    glUseProgram(program1);
    glUniform1i(glGetUniformLocation(program1, "texture"), 0);
    ANGLE_GL_PROGRAM(program2, kSamplerMetadataVertexShader1, kSamplerMetadataFragmentShader);
    glUseProgram(program2);
    glUniform1i(glGetUniformLocation(program2, "texture1"), 0);
    glUniform1i(glGetUniformLocation(program2, "texture2"), 0);

    // Draw a solid green color to the framebuffer.
    glUseProgram(program1);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    // Test that our first program is good.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Bind a different program that uses more samplers.
    // Draw another quad that depends on the sampler metadata.
    glUseProgram(program2);
    glDrawArrays(GL_TRIANGLES, 0, 3);
    // Flush via ReadPixels and check that it's still green.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    ASSERT_GL_NO_ERROR();
}

// Tests that redefining Buffer storage syncs with the Transform Feedback object.
TEST_P(StateChangeTestES3, RedefineTransformFeedbackBuffer)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsVulkan());
    // Create the most simple program possible - simple a passthrough for a float attribute.
    constexpr char kVertexShader[] = R"(#version 300 es
in float valueIn;
out float valueOut;
void main()
{
    gl_Position = vec4(0, 0, 0, 0);
    valueOut = valueIn;
})";

    constexpr char kFragmentShader[] = R"(#version 300 es
out mediump float dummy;
void main()
{
    dummy = 1.0;
})";

    std::vector<std::string> tfVaryings = {"valueOut"};
    ANGLE_GL_PROGRAM_TRANSFORM_FEEDBACK(program, kVertexShader, kFragmentShader, tfVaryings,
                                        GL_SEPARATE_ATTRIBS);
    glUseProgram(program);

    GLint attribLoc = glGetAttribLocation(program, "valueIn");
    ASSERT_NE(-1, attribLoc);

    // Disable rasterization - we're not interested in the framebuffer.
    glEnable(GL_RASTERIZER_DISCARD);

    // Initialize a float vertex buffer with 1.0.
    std::vector<GLfloat> data1(16, 1.0);
    GLsizei size1 = static_cast<GLsizei>(sizeof(GLfloat) * data1.size());

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, size1, data1.data(), GL_STATIC_DRAW);
    glVertexAttribPointer(attribLoc, 1, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(attribLoc);

    ASSERT_GL_NO_ERROR();

    // Initialize a same-sized XFB buffer.
    GLBuffer xfbBuffer;
    glBindBuffer(GL_TRANSFORM_FEEDBACK_BUFFER, xfbBuffer);
    glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER, size1, nullptr, GL_STATIC_DRAW);

    // Draw with XFB enabled.
    GLTransformFeedback xfb;
    glBindTransformFeedback(GL_TRANSFORM_FEEDBACK, xfb);
    glBindBufferBase(GL_TRANSFORM_FEEDBACK_BUFFER, 0, xfbBuffer);

    glBeginTransformFeedback(GL_POINTS);
    glDrawArrays(GL_POINTS, 0, 16);
    glEndTransformFeedback();

    ASSERT_GL_NO_ERROR();

    // Verify the XFB stage caught the 1.0 attribute values.
    void *mapped1     = glMapBufferRange(GL_TRANSFORM_FEEDBACK_BUFFER, 0, size1, GL_MAP_READ_BIT);
    GLfloat *asFloat1 = reinterpret_cast<GLfloat *>(mapped1);
    std::vector<GLfloat> actualData1(asFloat1, asFloat1 + data1.size());
    EXPECT_EQ(data1, actualData1);
    glUnmapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER);

    // Now, reinitialize the XFB buffer to a larger size, and draw with 2.0.
    std::vector<GLfloat> data2(128, 2.0);
    const GLsizei size2 = static_cast<GLsizei>(sizeof(GLfloat) * data2.size());
    glBufferData(GL_ARRAY_BUFFER, size2, data2.data(), GL_STATIC_DRAW);
    glBufferData(GL_TRANSFORM_FEEDBACK_BUFFER, size2, nullptr, GL_STATIC_DRAW);

    glBeginTransformFeedback(GL_POINTS);
    glDrawArrays(GL_POINTS, 0, 128);
    glEndTransformFeedback();

    ASSERT_GL_NO_ERROR();

    // Verify the XFB stage caught the 2.0 attribute values.
    void *mapped2     = glMapBufferRange(GL_TRANSFORM_FEEDBACK_BUFFER, 0, size2, GL_MAP_READ_BIT);
    GLfloat *asFloat2 = reinterpret_cast<GLfloat *>(mapped2);
    std::vector<GLfloat> actualData2(asFloat2, asFloat2 + data2.size());
    EXPECT_EQ(data2, actualData2);
    glUnmapBuffer(GL_TRANSFORM_FEEDBACK_BUFFER);
}

// Simple state change tests for line loop drawing. There is some very specific handling of line
// line loops in Vulkan and we need to test switching between drawElements and drawArrays calls to
// validate every edge cases.
class LineLoopStateChangeTest : public StateChangeTest
{
  protected:
    LineLoopStateChangeTest()
    {
        setWindowWidth(32);
        setWindowHeight(32);
        setConfigRedBits(8);
        setConfigGreenBits(8);
        setConfigBlueBits(8);
        setConfigAlphaBits(8);
    }

    void validateSquareAndHourglass() const
    {
        ASSERT_GL_NO_ERROR();

        int quarterWidth  = getWindowWidth() / 4;
        int quarterHeight = getWindowHeight() / 4;

        // Bottom left
        EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight, GLColor::blue);

        // Top left
        EXPECT_PIXEL_COLOR_EQ(quarterWidth, (quarterHeight * 3), GLColor::blue);

        // Top right
        // The last pixel isn't filled on a line loop so we check the pixel right before.
        EXPECT_PIXEL_COLOR_EQ((quarterWidth * 3), (quarterHeight * 3) - 1, GLColor::blue);

        // dead center to validate the hourglass.
        EXPECT_PIXEL_COLOR_EQ((quarterWidth * 2), quarterHeight * 2, GLColor::blue);

        // Verify line is closed between the 2 last vertices
        EXPECT_PIXEL_COLOR_EQ((quarterWidth * 2), quarterHeight, GLColor::blue);
    }
};

// Draw an hourglass with a drawElements call followed by a square with drawArrays.
TEST_P(LineLoopStateChangeTest, DrawElementsThenDrawArrays)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());
    glUseProgram(program);

    // We expect to draw a square with these 4 vertices with a drawArray call.
    std::vector<Vector3> vertices;
    CreatePixelCenterWindowCoords({{8, 8}, {8, 24}, {24, 24}, {24, 8}}, getWindowWidth(),
                                  getWindowHeight(), &vertices);

    // If we use these indices to draw however, we should be drawing an hourglass.
    auto indices = std::vector<GLushort>{0, 2, 1, 3};

    GLint mPositionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, mPositionLocation);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    GLBuffer indexBuffer;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), &indices[0],
                 GL_STATIC_DRAW);

    glVertexAttribPointer(mPositionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(mPositionLocation);
    glClear(GL_COLOR_BUFFER_BIT);
    glDrawElements(GL_LINE_LOOP, 4, GL_UNSIGNED_SHORT, nullptr);  // hourglass
    glDrawArrays(GL_LINE_LOOP, 0, 4);                             // square
    glDisableVertexAttribArray(mPositionLocation);

    validateSquareAndHourglass();
}

// Draw line loop using a drawArrays followed by an hourglass with drawElements.
TEST_P(LineLoopStateChangeTest, DrawArraysThenDrawElements)
{
    // http://anglebug.com/2856: Seems to fail on older drivers and pass on newer.
    // Tested failing on 18.3.3 and passing on 18.9.2.
    ANGLE_SKIP_TEST_IF(IsAMD() && IsVulkan() && IsWindows());

    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());
    glUseProgram(program);

    // We expect to draw a square with these 4 vertices with a drawArray call.
    std::vector<Vector3> vertices;
    CreatePixelCenterWindowCoords({{8, 8}, {8, 24}, {24, 24}, {24, 8}}, getWindowWidth(),
                                  getWindowHeight(), &vertices);

    // If we use these indices to draw however, we should be drawing an hourglass.
    auto indices = std::vector<GLushort>{0, 2, 1, 3};

    GLint mPositionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, mPositionLocation);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    GLBuffer indexBuffer;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), &indices[0],
                 GL_STATIC_DRAW);

    glVertexAttribPointer(mPositionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(mPositionLocation);
    glClear(GL_COLOR_BUFFER_BIT);
    glDrawArrays(GL_LINE_LOOP, 0, 4);                             // square
    glDrawElements(GL_LINE_LOOP, 4, GL_UNSIGNED_SHORT, nullptr);  // hourglass
    glDisableVertexAttribArray(mPositionLocation);

    validateSquareAndHourglass();
}

// Draw a triangle with a drawElements call and a non-zero offset and draw the same
// triangle with the same offset again followed by a line loop with drawElements.
TEST_P(LineLoopStateChangeTest, DrawElementsThenDrawElements)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());

    glUseProgram(program);

    // Background Red color
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // We expect to draw a triangle with the last three points on the bottom right,
    // draw with LineLoop, and then draw a triangle with the same non-zero offset.
    auto vertices = std::vector<Vector3>{
        {-1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 0.0f}, {1.0f, -1.0f, 0.0f}, {-1.0f, -1.0f, 0.0f}};

    auto indices = std::vector<GLushort>{0, 1, 2, 1, 2, 3};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLBuffer indexBuffer;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), &indices[0],
                 GL_STATIC_DRAW);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    // Draw a triangle with a non-zero offset on the bottom right.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, (void *)(3 * sizeof(GLushort)));

    // Draw with LineLoop.
    glDrawElements(GL_LINE_LOOP, 3, GL_UNSIGNED_SHORT, nullptr);

    // Draw the triangle again with the same offset.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, (void *)(3 * sizeof(GLushort)));

    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth  = getWindowWidth() / 4;
    int quarterHeight = getWindowHeight() / 4;

    // Validate the top left point's color.
    EXPECT_PIXEL_COLOR_EQ(0, getWindowHeight() - 1, GLColor::blue);

    // Validate the triangle is drawn on the bottom right.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight, GLColor::blue);

    // Validate the triangle is NOT on the top left part.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight * 3, GLColor::red);
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight * 2, GLColor::red);
}

// Simple state change tests, primarily focused on basic object lifetime and dependency management
// with back-ends that don't support that automatically (i.e. Vulkan).
class SimpleStateChangeTest : public ANGLETest
{
  protected:
    static constexpr int kWindowSize = 64;

    SimpleStateChangeTest()
    {
        setWindowWidth(kWindowSize);
        setWindowHeight(kWindowSize);
        setConfigRedBits(8);
        setConfigGreenBits(8);
        setConfigBlueBits(8);
        setConfigAlphaBits(8);
    }

    void simpleDrawWithBuffer(GLBuffer *buffer);
    void simpleDrawWithColor(const GLColor &color);

    using UpdateFunc = std::function<void(GLenum, GLTexture *, GLint, GLint, const GLColor &)>;
    void updateTextureBoundToFramebufferHelper(UpdateFunc updateFunc);
    void bindTextureToFbo(GLFramebuffer &fbo, GLTexture &texture);
    void drawToFboWithCulling(const GLenum frontFace, bool earlyFrontFaceDirty);
};

class SimpleStateChangeTestES3 : public SimpleStateChangeTest
{};

class SimpleStateChangeTestES31 : public SimpleStateChangeTest
{};

class SimpleStateChangeTestComputeES31 : public SimpleStateChangeTest
{
  protected:
    void testSetUp() override
    {
        glGenFramebuffers(1, &mFramebuffer);
        glGenTextures(1, &mTexture);

        glBindTexture(GL_TEXTURE_2D, mTexture);
        glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, 2, 2);
        EXPECT_GL_NO_ERROR();

        constexpr char kCS[] = R"(#version 310 es
layout(local_size_x=2, local_size_y=2) in;
layout (rgba8, binding = 0) readonly uniform highp image2D srcImage;
layout (rgba8, binding = 1) writeonly uniform highp image2D dstImage;
void main()
{
    imageStore(dstImage, ivec2(gl_LocalInvocationID.xy),
               imageLoad(srcImage, ivec2(gl_LocalInvocationID.xy)));
})";

        mProgram = CompileComputeProgram(kCS);
        ASSERT_NE(mProgram, 0u);

        glBindImageTexture(1, mTexture, 0, GL_FALSE, 0, GL_WRITE_ONLY, GL_RGBA8);

        glBindFramebuffer(GL_READ_FRAMEBUFFER, mFramebuffer);
        glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mTexture,
                               0);

        ASSERT_GL_NO_ERROR();
    }

    void testTearDown() override
    {
        if (mFramebuffer != 0)
        {
            glDeleteFramebuffers(1, &mFramebuffer);
            mFramebuffer = 0;
        }

        if (mTexture != 0)
        {
            glDeleteTextures(1, &mTexture);
            mTexture = 0;
        }
        glDeleteProgram(mProgram);
    }

    GLuint mProgram;
    GLuint mFramebuffer = 0;
    GLuint mTexture     = 0;
};

constexpr char kSimpleVertexShader[] = R"(attribute vec2 position;
attribute vec4 color;
varying vec4 vColor;
void main()
{
    gl_Position = vec4(position, 0, 1);
    vColor = color;
}
)";

constexpr char kSimpleFragmentShader[] = R"(precision mediump float;
varying vec4 vColor;
void main()
{
    gl_FragColor = vColor;
}
)";

void SimpleStateChangeTest::simpleDrawWithBuffer(GLBuffer *buffer)
{
    ANGLE_GL_PROGRAM(program, kSimpleVertexShader, kSimpleFragmentShader);
    glUseProgram(program);

    GLint colorLoc = glGetAttribLocation(program, "color");
    ASSERT_NE(-1, colorLoc);

    glBindBuffer(GL_ARRAY_BUFFER, *buffer);
    glVertexAttribPointer(colorLoc, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);
    glEnableVertexAttribArray(colorLoc);

    drawQuad(program, "position", 0.5f, 1.0f, true);
    ASSERT_GL_NO_ERROR();
}

void SimpleStateChangeTest::simpleDrawWithColor(const GLColor &color)
{
    std::vector<GLColor> colors(6, color);
    GLBuffer colorBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, colorBuffer);
    glBufferData(GL_ARRAY_BUFFER, colors.size() * sizeof(GLColor), colors.data(), GL_STATIC_DRAW);
    simpleDrawWithBuffer(&colorBuffer);
}

// Test that we can do a drawElements call successfully after making a drawArrays call in the same
// frame.
TEST_P(SimpleStateChangeTest, DrawArraysThenDrawElements)
{
    // http://anglebug.com/4121
    ANGLE_SKIP_TEST_IF(IsIntel() && IsLinux() && IsOpenGLES());
    // httpL//anglebug.com/4177
    ANGLE_SKIP_TEST_IF(IsNVIDIA() && IsOSX() && IsMetal());
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());
    glUseProgram(program);

    // We expect to draw a triangle with the first 3 points to the left, then another triangle with
    // the last 3 vertices using a drawElements call.
    auto vertices = std::vector<Vector3>{{-1.0f, -1.0f, 0.0f},
                                         {-1.0f, 1.0f, 0.0f},
                                         {0.0f, 0.0f, 0.0f},
                                         {1.0f, 1.0f, 0.0f},
                                         {1.0f, -1.0f, 0.0f}};

    // If we use these indices to draw we'll be using the last 2 vertex only to draw.
    auto indices = std::vector<GLushort>{2, 3, 4};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    GLBuffer indexBuffer;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), &indices[0],
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    for (int i = 0; i < 10; i++)
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glDrawArrays(GL_TRIANGLES, 0, 3);                             // triangle to the left
        glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, nullptr);  // triangle to the right
        swapBuffers();
    }
    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth = getWindowWidth() / 4;
    int halfHeight   = getWindowHeight() / 2;

    // Validate triangle to the left
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, halfHeight, GLColor::blue);

    // Validate triangle to the right
    EXPECT_PIXEL_COLOR_EQ((quarterWidth * 3), halfHeight, GLColor::blue);
}

// Draw a triangle with drawElements and a non-zero offset and draw the same
// triangle with the same offset followed by binding the same element buffer.
TEST_P(SimpleStateChangeTest, DrawElementsThenDrawElements)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Blue());

    glUseProgram(program);

    // Background Red color
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // We expect to draw the triangle with the last three points on the bottom right, and
    // rebind the same element buffer and draw with the same indices.
    auto vertices = std::vector<Vector3>{
        {-1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 0.0f}, {1.0f, -1.0f, 0.0f}, {-1.0f, -1.0f, 0.0f}};

    auto indices = std::vector<GLushort>{0, 1, 2, 1, 2, 3};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLBuffer indexBuffer;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), &indices[0],
                 GL_STATIC_DRAW);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, (void *)(3 * sizeof(GLushort)));

    // Rebind the same element buffer.
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);

    // Draw the triangle again with the same offset.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, (void *)(3 * sizeof(GLushort)));

    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth  = getWindowWidth() / 4;
    int quarterHeight = getWindowHeight() / 4;

    // Validate the triangle is drawn on the bottom right.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight, GLColor::blue);

    // Validate the triangle is NOT on the top left part.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight * 3, GLColor::red);
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight * 2, GLColor::red);
}

// Draw a triangle with drawElements then change the index buffer and draw again.
TEST_P(SimpleStateChangeTest, DrawElementsThenDrawElementsNewIndexBuffer)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::UniformColor());

    glUseProgram(program);

    // Background Red color
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // We expect to draw the triangle with the last three points on the bottom right, and
    // rebind the same element buffer and draw with the same indices.
    auto vertices = std::vector<Vector3>{
        {-1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 0.0f}, {1.0f, -1.0f, 0.0f}, {-1.0f, -1.0f, 0.0f}};

    auto indices8 = std::vector<GLubyte>{0, 1, 2, 1, 2, 3};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLint colorUniformLocation =
        glGetUniformLocation(program, angle::essl1_shaders::ColorUniform());
    ASSERT_NE(colorUniformLocation, -1);

    glUniform4f(colorUniformLocation, 1.0f, 1.0f, 1.0f, 1.0f);

    GLBuffer indexBuffer8;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer8);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices8.size() * sizeof(GLubyte), &indices8[0],
                 GL_STATIC_DRAW);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    auto indices2nd8 = std::vector<GLubyte>{2, 3, 0, 0, 1, 2};

    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices2nd8.size() * sizeof(GLubyte), &indices2nd8[0],
                 GL_STATIC_DRAW);

    glUniform4f(colorUniformLocation, 0.0f, 0.0f, 1.0f, 1.0f);

    // Draw the triangle again with the same offset.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth  = getWindowWidth() / 4;
    int quarterHeight = getWindowHeight() / 4;

    // Validate the triangle is drawn on the bottom left.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight * 2, GLColor::blue);

    // Validate the triangle is NOT on the top right part.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight * 3, GLColor::white);
}

// Draw a triangle with drawElements then change the indices and draw again.
TEST_P(SimpleStateChangeTest, DrawElementsThenDrawElementsNewIndices)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::UniformColor());

    glUseProgram(program);

    // Background Red color
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // We expect to draw the triangle with the last three points on the bottom right, and
    // rebind the same element buffer and draw with the same indices.
    auto vertices = std::vector<Vector3>{
        {-1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 0.0f}, {1.0f, -1.0f, 0.0f}, {-1.0f, -1.0f, 0.0f}};

    auto indices8 = std::vector<GLubyte>{0, 1, 2, 2, 3, 0};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLint colorUniformLocation =
        glGetUniformLocation(program, angle::essl1_shaders::ColorUniform());
    ASSERT_NE(colorUniformLocation, -1);

    glUniform4f(colorUniformLocation, 1.0f, 1.0f, 1.0f, 1.0f);

    GLBuffer indexBuffer8;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer8);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices8.size() * sizeof(GLubyte), &indices8[0],
                 GL_DYNAMIC_DRAW);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    auto newIndices8 = std::vector<GLubyte>{2, 3, 0};

    glBufferSubData(GL_ELEMENT_ARRAY_BUFFER, 0, newIndices8.size() * sizeof(GLubyte),
                    &newIndices8[0]);

    glUniform4f(colorUniformLocation, 0.0f, 0.0f, 1.0f, 1.0f);

    // Draw the triangle again with the same offset.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth  = getWindowWidth() / 4;
    int quarterHeight = getWindowHeight() / 4;

    // Validate the triangle is drawn on the bottom left.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight * 2, GLColor::blue);

    // Validate the triangle is NOT on the top right part.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight * 3, GLColor::white);
}

// Draw a triangle with drawElements and a non-zero offset and draw the same
// triangle with the same offset followed by binding a USHORT element buffer.
TEST_P(SimpleStateChangeTest, DrawElementsUBYTEX2ThenDrawElementsUSHORT)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::UniformColor());

    glUseProgram(program);

    // Background Red color
    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // We expect to draw the triangle with the last three points on the bottom right, and
    // rebind the same element buffer and draw with the same indices.
    auto vertices = std::vector<Vector3>{
        {-1.0f, 1.0f, 0.0f}, {1.0f, 1.0f, 0.0f}, {1.0f, -1.0f, 0.0f}, {-1.0f, -1.0f, 0.0f}};

    auto indices8 = std::vector<GLubyte>{0, 1, 2, 1, 2, 3};

    GLint positionLocation = glGetAttribLocation(program, essl1_shaders::PositionAttrib());
    ASSERT_NE(-1, positionLocation);

    GLint colorUniformLocation =
        glGetUniformLocation(program, angle::essl1_shaders::ColorUniform());
    ASSERT_NE(colorUniformLocation, -1);

    glUniform4f(colorUniformLocation, 1.0f, 1.0f, 1.0f, 1.0f);

    GLBuffer indexBuffer8;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer8);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices8.size() * sizeof(GLubyte), &indices8[0],
                 GL_STATIC_DRAW);

    GLBuffer vertexBuffer;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices[0]) * vertices.size(), vertices.data(),
                 GL_STATIC_DRAW);

    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(positionLocation);

    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    auto indices2nd8 = std::vector<GLubyte>{2, 3, 0, 0, 1, 2};
    GLBuffer indexBuffer2nd8;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer2nd8);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices2nd8.size() * sizeof(GLubyte), &indices2nd8[0],
                 GL_STATIC_DRAW);
    glUniform4f(colorUniformLocation, 0.0f, 1.0f, 0.0f, 1.0f);

    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_BYTE, (void *)(0 * sizeof(GLubyte)));

    // Bind the 16bit element buffer.
    auto indices16 = std::vector<GLushort>{0, 1, 3, 1, 2, 3};
    GLBuffer indexBuffer16;
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer16);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices16.size() * sizeof(GLushort), &indices16[0],
                 GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer16);

    glUniform4f(colorUniformLocation, 0.0f, 0.0f, 1.0f, 1.0f);

    // Draw the triangle again with the same offset.
    glDrawElements(GL_TRIANGLES, 3, GL_UNSIGNED_SHORT, (void *)(0 * sizeof(GLushort)));

    glDisableVertexAttribArray(positionLocation);

    ASSERT_GL_NO_ERROR();

    int quarterWidth  = getWindowWidth() / 4;
    int quarterHeight = getWindowHeight() / 4;

    // Validate green triangle is drawn on the bottom.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight, GLColor::green);

    // Validate white triangle is drawn on the right.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 3, quarterHeight * 2, GLColor::white);

    // Validate blue triangle is on the top left part.
    EXPECT_PIXEL_COLOR_EQ(quarterWidth * 2, quarterHeight * 3, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(quarterWidth, quarterHeight * 2, GLColor::blue);
}

// Draw a points use multiple unaligned vertex buffer with same data,
// verify all the rendering results are the same.
TEST_P(SimpleStateChangeTest, DrawRepeatUnalignedVboChange)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(isSwiftshader() && IsWindows());
    const int kRepeat = 2;

    // set up VBO, colorVBO is unaligned
    GLBuffer positionBuffer;
    constexpr size_t posOffset = 0;
    const GLfloat posData[]    = {0.5f, 0.5f};
    glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(posData), posData, GL_STATIC_DRAW);

    GLBuffer colorBuffers[kRepeat];
    constexpr size_t colorOffset                = 1;
    const GLfloat colorData[]                   = {0.515f, 0.515f, 0.515f, 1.0f};
    constexpr size_t colorBufferSize            = colorOffset + sizeof(colorData);
    uint8_t colorDataUnaligned[colorBufferSize] = {0};
    memcpy(reinterpret_cast<void *>(colorDataUnaligned + colorOffset), colorData,
           sizeof(colorData));
    for (uint32_t i = 0; i < kRepeat; i++)
    {
        glBindBuffer(GL_ARRAY_BUFFER, colorBuffers[i]);
        glBufferData(GL_ARRAY_BUFFER, colorBufferSize, colorDataUnaligned, GL_STATIC_DRAW);
    }

    // set up frame buffer
    GLFramebuffer framebuffer;
    GLTexture framebufferTexture;
    bindTextureToFbo(framebuffer, framebufferTexture);

    // set up program
    ANGLE_GL_PROGRAM(program, kSimpleVertexShader, kSimpleFragmentShader);
    glUseProgram(program);
    GLuint colorAttrLocation = glGetAttribLocation(program, "color");
    glEnableVertexAttribArray(colorAttrLocation);
    GLuint posAttrLocation = glGetAttribLocation(program, "position");
    glEnableVertexAttribArray(posAttrLocation);
    EXPECT_GL_NO_ERROR();

    // draw and get drawing results
    constexpr size_t kRenderSize = kWindowSize * kWindowSize;
    std::array<GLColor, kRenderSize> pixelBufs[kRepeat];

    for (uint32_t i = 0; i < kRepeat; i++)
    {
        glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        glBindBuffer(GL_ARRAY_BUFFER, positionBuffer);
        glVertexAttribPointer(posAttrLocation, 2, GL_FLOAT, GL_FALSE, 0,
                              reinterpret_cast<const void *>(posOffset));
        glBindBuffer(GL_ARRAY_BUFFER, colorBuffers[i]);
        glVertexAttribPointer(colorAttrLocation, 4, GL_FLOAT, GL_FALSE, 0,
                              reinterpret_cast<const void *>(colorOffset));

        glDrawArrays(GL_POINTS, 0, 1);

        // read drawing results
        glReadPixels(0, 0, kWindowSize, kWindowSize, GL_RGBA, GL_UNSIGNED_BYTE,
                     pixelBufs[i].data());
        EXPECT_GL_NO_ERROR();
    }

    // verify something is drawn
    static_assert(kRepeat >= 2, "More than one repetition required");
    std::array<GLColor, kRenderSize> pixelAllBlack{0};
    EXPECT_NE(pixelBufs[0], pixelAllBlack);
    // verify drawing results are all identical
    for (uint32_t i = 1; i < kRepeat; i++)
    {
        EXPECT_EQ(pixelBufs[i - 1], pixelBufs[i]);
    }
}

// Handles deleting a Buffer when it's being used.
TEST_P(SimpleStateChangeTest, DeleteBufferInUse)
{
    std::vector<GLColor> colorData(6, GLColor::red);

    GLBuffer buffer;
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLColor) * colorData.size(), colorData.data(),
                 GL_STATIC_DRAW);

    simpleDrawWithBuffer(&buffer);

    buffer.reset();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
}

// Tests that resizing a Buffer during a draw works as expected.
TEST_P(SimpleStateChangeTest, RedefineBufferInUse)
{
    std::vector<GLColor> redColorData(6, GLColor::red);

    GLBuffer buffer;
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLColor) * redColorData.size(), redColorData.data(),
                 GL_STATIC_DRAW);

    // Trigger a pull from the buffer.
    simpleDrawWithBuffer(&buffer);

    // Redefine the buffer that's in-flight.
    std::vector<GLColor> greenColorData(1024, GLColor::green);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLColor) * greenColorData.size(), greenColorData.data(),
                 GL_STATIC_DRAW);

    // Trigger the flush and verify the first draw worked.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Draw again and verify the new data is correct.
    simpleDrawWithBuffer(&buffer);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
}

// Tests updating a buffer's contents while in use, without redefining it.
TEST_P(SimpleStateChangeTest, UpdateBufferInUse)
{
    std::vector<GLColor> redColorData(6, GLColor::red);

    GLBuffer buffer;
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(GLColor) * redColorData.size(), redColorData.data(),
                 GL_STATIC_DRAW);

    // Trigger a pull from the buffer.
    simpleDrawWithBuffer(&buffer);

    // Update the buffer that's in-flight.
    std::vector<GLColor> greenColorData(6, GLColor::green);
    glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(GLColor) * greenColorData.size(),
                    greenColorData.data());

    // Trigger the flush and verify the first draw worked.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Draw again and verify the new data is correct.
    simpleDrawWithBuffer(&buffer);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
}

// Tests that deleting an in-flight Texture does not immediately delete the resource.
TEST_P(SimpleStateChangeTest, DeleteTextureInUse)
{
    std::array<GLColor, 4> colors = {
        {GLColor::red, GLColor::green, GLColor::blue, GLColor::yellow}};

    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colors.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    draw2DTexturedQuad(0.5f, 1.0f, true);
    tex.reset();
    EXPECT_GL_NO_ERROR();

    int w = getWindowWidth() - 2;
    int h = getWindowHeight() - 2;

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    EXPECT_PIXEL_COLOR_EQ(w, 0, GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(0, h, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(w, h, GLColor::yellow);
}

// Tests that modifying a texture parameter in-flight does not cause problems.
TEST_P(SimpleStateChangeTest, ChangeTextureFilterModeBetweenTwoDraws)
{
    std::array<GLColor, 4> colors = {
        {GLColor::black, GLColor::white, GLColor::black, GLColor::white}};

    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colors.data());

    glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Draw to the left side of the window only with NEAREST.
    glViewport(0, 0, getWindowWidth() / 2, getWindowHeight());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    draw2DTexturedQuad(0.5f, 1.0f, true);

    // Draw to the right side of the window only with LINEAR.
    glViewport(getWindowWidth() / 2, 0, getWindowWidth() / 2, getWindowHeight());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    draw2DTexturedQuad(0.5f, 1.0f, true);
    EXPECT_GL_NO_ERROR();

    glViewport(0, 0, getWindowWidth(), getWindowHeight());

    // The first half (left) should be only black followed by plain white.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::black);
    EXPECT_PIXEL_COLOR_EQ(1, 0, GLColor::black);
    EXPECT_PIXEL_COLOR_EQ((getWindowWidth() / 2) - 3, 0, GLColor::white);
    EXPECT_PIXEL_COLOR_EQ((getWindowWidth() / 2) - 4, 0, GLColor::white);

    // The second half (right) should be a gradient so we shouldn't find plain black/white in the
    // middle.
    EXPECT_NE(angle::ReadColor((getWindowWidth() / 4) * 3, 0), GLColor::black);
    EXPECT_NE(angle::ReadColor((getWindowWidth() / 4) * 3, 0), GLColor::white);
}

// Tests that bind the same texture all the time between different draw calls.
TEST_P(SimpleStateChangeTest, RebindTextureDrawAgain)
{
    GLuint program = get2DTexturedQuadProgram();
    glUseProgram(program);

    std::array<GLColor, 4> colors = {{GLColor::cyan, GLColor::cyan, GLColor::cyan, GLColor::cyan}};

    // Setup the texture
    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colors.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    // Setup the vertex array to draw a quad.
    GLint positionLocation = glGetAttribLocation(program, "position");
    setupQuadVertexBuffer(1.0f, 1.0f);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(positionLocation);

    // Draw quad
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Bind again
    glBindTexture(GL_TEXTURE_2D, tex);
    ASSERT_GL_NO_ERROR();

    // Draw again, should still work.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Validate whole surface is filled with cyan.
    int h = getWindowHeight() - 1;
    int w = getWindowWidth() - 1;

    EXPECT_PIXEL_RECT_EQ(0, 0, w, h, GLColor::cyan);
}

// Tests that we can draw with a texture, modify the texture with a texSubImage, and then draw again
// correctly.
TEST_P(SimpleStateChangeTest, DrawWithTextureTexSubImageThenDrawAgain)
{
    GLuint program = get2DTexturedQuadProgram();
    ASSERT_NE(0u, program);
    glUseProgram(program);

    std::array<GLColor, 4> colors    = {{GLColor::red, GLColor::red, GLColor::red, GLColor::red}};
    std::array<GLColor, 4> subColors = {
        {GLColor::green, GLColor::green, GLColor::green, GLColor::green}};

    // Setup the texture
    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colors.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    // Setup the vertex array to draw a quad.
    GLint positionLocation = glGetAttribLocation(program, "position");
    setupQuadVertexBuffer(1.0f, 1.0f);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(positionLocation);

    // Draw quad
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Update bottom-half of texture with green.
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 2, 1, GL_RGBA, GL_UNSIGNED_BYTE, subColors.data());
    ASSERT_GL_NO_ERROR();

    // Draw again, should still work.
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Validate first half of the screen is red and the bottom is green.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(0, getWindowHeight() / 4 * 3, GLColor::red);
}

// Test that we can alternate between textures between different draws.
TEST_P(SimpleStateChangeTest, DrawTextureAThenTextureBThenTextureA)
{
    GLuint program = get2DTexturedQuadProgram();
    glUseProgram(program);

    std::array<GLColor, 4> colorsTex1 = {
        {GLColor::cyan, GLColor::cyan, GLColor::cyan, GLColor::cyan}};

    std::array<GLColor, 4> colorsTex2 = {
        {GLColor::magenta, GLColor::magenta, GLColor::magenta, GLColor::magenta}};

    // Setup the texture
    GLTexture tex1;
    glBindTexture(GL_TEXTURE_2D, tex1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colorsTex1.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    GLTexture tex2;
    glBindTexture(GL_TEXTURE_2D, tex2);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colorsTex2.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    // Setup the vertex array to draw a quad.
    GLint positionLocation = glGetAttribLocation(program, "position");
    setupQuadVertexBuffer(1.0f, 1.0f);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(positionLocation);

    // Draw quad
    glBindTexture(GL_TEXTURE_2D, tex1);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Bind again, draw again
    glBindTexture(GL_TEXTURE_2D, tex2);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    // Bind again, draw again
    glBindTexture(GL_TEXTURE_2D, tex1);
    glDrawArrays(GL_TRIANGLES, 0, 6);

    // Validate whole surface is filled with cyan.
    int h = getWindowHeight() - 1;
    int w = getWindowWidth() - 1;

    EXPECT_PIXEL_RECT_EQ(0, 0, w, h, GLColor::cyan);
}

// Tests that redefining an in-flight Texture does not affect the in-flight resource.
TEST_P(SimpleStateChangeTest, RedefineTextureInUse)
{
    std::array<GLColor, 4> colors = {
        {GLColor::red, GLColor::green, GLColor::blue, GLColor::yellow}};

    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, colors.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    // Draw with the first texture.
    draw2DTexturedQuad(0.5f, 1.0f, true);

    // Redefine the in-flight texture.
    constexpr int kBigSize = 32;
    std::vector<GLColor> bigColors;
    for (int y = 0; y < kBigSize; ++y)
    {
        for (int x = 0; x < kBigSize; ++x)
        {
            bool xComp = x < kBigSize / 2;
            bool yComp = y < kBigSize / 2;
            if (yComp)
            {
                bigColors.push_back(xComp ? GLColor::cyan : GLColor::magenta);
            }
            else
            {
                bigColors.push_back(xComp ? GLColor::yellow : GLColor::white);
            }
        }
    }

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE, bigColors.data());
    EXPECT_GL_NO_ERROR();

    // Verify the first draw had the correct data via ReadPixels.
    int w = getWindowWidth() - 2;
    int h = getWindowHeight() - 2;

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    EXPECT_PIXEL_COLOR_EQ(w, 0, GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(0, h, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(w, h, GLColor::yellow);

    // Draw and verify with the redefined data.
    draw2DTexturedQuad(0.5f, 1.0f, true);
    EXPECT_GL_NO_ERROR();

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::cyan);
    EXPECT_PIXEL_COLOR_EQ(w, 0, GLColor::magenta);
    EXPECT_PIXEL_COLOR_EQ(0, h, GLColor::yellow);
    EXPECT_PIXEL_COLOR_EQ(w, h, GLColor::white);
}

// Test updating a Texture's contents while in use by GL works as expected.
TEST_P(SimpleStateChangeTest, UpdateTextureInUse)
{
    std::array<GLColor, 4> rgby = {{GLColor::red, GLColor::green, GLColor::blue, GLColor::yellow}};

    // Set up 2D quad resources.
    GLuint program = get2DTexturedQuadProgram();
    glUseProgram(program);
    ASSERT_EQ(0, glGetAttribLocation(program, "position"));

    const auto &quadVerts = GetQuadVertices();

    GLBuffer vbo;
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, quadVerts.size() * sizeof(quadVerts[0]), quadVerts.data(),
                 GL_STATIC_DRAW);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
    glEnableVertexAttribArray(0);

    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, rgby.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    // Draw RGBY to the Framebuffer. The texture is now in-use by GL.
    const int w  = getWindowWidth() - 2;
    const int h  = getWindowHeight() - 2;
    const int w2 = w >> 1;

    glViewport(0, 0, w2, h);
    glDrawArrays(GL_TRIANGLES, 0, 6);

    // Update the texture to be YBGR, while the Texture is in-use. Should not affect the draw.
    std::array<GLColor, 4> ybgr = {{GLColor::yellow, GLColor::blue, GLColor::green, GLColor::red}};
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 2, 2, GL_RGBA, GL_UNSIGNED_BYTE, ybgr.data());
    ASSERT_GL_NO_ERROR();

    // Draw again to the Framebuffer. The second draw call should use the updated YBGR data.
    glViewport(w2, 0, w2, h);
    glDrawArrays(GL_TRIANGLES, 0, 6);

    // Check the Framebuffer. Both draws should have completed.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    EXPECT_PIXEL_COLOR_EQ(w2 - 1, 0, GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(0, h - 1, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(w2 - 1, h - 1, GLColor::yellow);

    EXPECT_PIXEL_COLOR_EQ(w2 + 1, 0, GLColor::yellow);
    EXPECT_PIXEL_COLOR_EQ(w - 1, 0, GLColor::blue);
    EXPECT_PIXEL_COLOR_EQ(w2 + 1, h - 1, GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(w - 1, h - 1, GLColor::red);
    ASSERT_GL_NO_ERROR();
}

void SimpleStateChangeTest::updateTextureBoundToFramebufferHelper(UpdateFunc updateFunc)
{
    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_ANGLE_framebuffer_blit"));

    std::vector<GLColor> red(4, GLColor::red);
    std::vector<GLColor> green(4, GLColor::green);

    GLTexture renderTarget;
    glBindTexture(GL_TEXTURE_2D, renderTarget);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, red.data());

    GLFramebuffer fbo;
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo);
    glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, renderTarget,
                           0);
    ASSERT_GL_FRAMEBUFFER_COMPLETE(GL_DRAW_FRAMEBUFFER);
    glViewport(0, 0, 2, 2);
    ASSERT_GL_NO_ERROR();

    GLTexture tex;
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, red.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    // Draw once to flush dirty state bits.
    draw2DTexturedQuad(0.5f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    // Update the (0, 1) pixel to be blue
    updateFunc(GL_TEXTURE_2D, &renderTarget, 0, 1, GLColor::blue);

    // Draw green to the right half of the Framebuffer.
    glBindTexture(GL_TEXTURE_2D, tex);
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 2, 2, GL_RGBA, GL_UNSIGNED_BYTE, green.data());
    glViewport(1, 0, 1, 2);
    draw2DTexturedQuad(0.5f, 1.0f, true);

    // Update the (1, 1) pixel to be yellow
    updateFunc(GL_TEXTURE_2D, &renderTarget, 1, 1, GLColor::yellow);

    ASSERT_GL_NO_ERROR();

    // Verify we have a quad with the right colors in the FBO.
    std::vector<GLColor> expected = {
        {GLColor::red, GLColor::green, GLColor::blue, GLColor::yellow}};
    std::vector<GLColor> actual(4);
    glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo);
    glReadPixels(0, 0, 2, 2, GL_RGBA, GL_UNSIGNED_BYTE, actual.data());
    EXPECT_EQ(expected, actual);
}

// Tests that TexSubImage updates are flushed before rendering.
TEST_P(SimpleStateChangeTest, TexSubImageOnTextureBoundToFrambuffer)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsAndroid() && IsOpenGLES());
    auto updateFunc = [](GLenum textureBinding, GLTexture *tex, GLint x, GLint y,
                         const GLColor &color) {
        glBindTexture(textureBinding, *tex);
        glTexSubImage2D(textureBinding, 0, x, y, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, color.data());
    };

    updateTextureBoundToFramebufferHelper(updateFunc);
}

// Tests that CopyTexSubImage updates are flushed before rendering.
TEST_P(SimpleStateChangeTest, CopyTexSubImageOnTextureBoundToFrambuffer)
{
    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_ANGLE_framebuffer_blit"));

    GLTexture copySource;
    glBindTexture(GL_TEXTURE_2D, copySource);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    GLFramebuffer copyFBO;
    glBindFramebuffer(GL_READ_FRAMEBUFFER, copyFBO);
    glFramebufferTexture2D(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, copySource, 0);

    ASSERT_GL_NO_ERROR();
    ASSERT_GL_FRAMEBUFFER_COMPLETE(GL_READ_FRAMEBUFFER);

    auto updateFunc = [&copySource](GLenum textureBinding, GLTexture *tex, GLint x, GLint y,
                                    const GLColor &color) {
        glBindTexture(GL_TEXTURE_2D, copySource);
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, color.data());

        glBindTexture(textureBinding, *tex);
        glCopyTexSubImage2D(textureBinding, 0, x, y, 0, 0, 1, 1);
    };

    updateTextureBoundToFramebufferHelper(updateFunc);
}

// Tests that the read framebuffer doesn't affect what the draw call thinks the attachments are
// (which is what the draw framebuffer dictates) when a command is issued with the GL_FRAMEBUFFER
// target.
TEST_P(SimpleStateChangeTestES3, ReadFramebufferDrawFramebufferDifferentAttachments)
{
    // http://anglebug.com/4092
    ANGLE_SKIP_TEST_IF(IsAndroid() && IsOpenGLES());

    GLRenderbuffer drawColorBuffer;
    glBindRenderbuffer(GL_RENDERBUFFER, drawColorBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 1, 1);

    GLRenderbuffer drawDepthBuffer;
    glBindRenderbuffer(GL_RENDERBUFFER, drawDepthBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, 1, 1);

    GLRenderbuffer readColorBuffer;
    glBindRenderbuffer(GL_RENDERBUFFER, readColorBuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 1, 1);

    GLFramebuffer drawFBO;
    glBindFramebuffer(GL_DRAW_FRAMEBUFFER, drawFBO);
    glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
                              drawColorBuffer);
    glFramebufferRenderbuffer(GL_DRAW_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER,
                              drawDepthBuffer);
    ASSERT_GL_FRAMEBUFFER_COMPLETE(GL_DRAW_FRAMEBUFFER);

    GLFramebuffer readFBO;
    glBindFramebuffer(GL_READ_FRAMEBUFFER, readFBO);
    glFramebufferRenderbuffer(GL_READ_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER,
                              readColorBuffer);
    ASSERT_GL_FRAMEBUFFER_COMPLETE(GL_READ_FRAMEBUFFER);

    EXPECT_GL_NO_ERROR();

    glClearDepthf(1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    // A handful of non-draw calls can sync framebuffer state, such as discard, invalidate,
    // invalidateSub and multisamplefv.  The trick here is to give GL_FRAMEBUFFER as target, which
    // includes both the read and draw framebuffers.  The test is to make sure syncing the read
    // framebuffer doesn't affect the draw call.
    GLenum invalidateAttachment = GL_COLOR_ATTACHMENT0;
    glInvalidateFramebuffer(GL_FRAMEBUFFER, 1, &invalidateAttachment);
    EXPECT_GL_NO_ERROR();

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_EQUAL);

    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Passthrough(), essl1_shaders::fs::Blue());

    drawQuad(program, essl1_shaders::PositionAttrib(), 1.0f);
    EXPECT_GL_NO_ERROR();

    glBindFramebuffer(GL_READ_FRAMEBUFFER, drawFBO);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::blue);
}

// Tests deleting a Framebuffer that is in use.
TEST_P(SimpleStateChangeTest, DeleteFramebufferInUse)
{
    constexpr int kSize = 16;

    // Create a simple framebuffer.
    GLTexture texture;
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kSize, kSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    GLFramebuffer framebuffer;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    glViewport(0, 0, kSize, kSize);

    // Draw a solid red color to the framebuffer.
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());
    drawQuad(program, essl1_shaders::PositionAttrib(), 0.5f, 1.0f, true);

    // Delete the framebuffer while the call is in flight.
    framebuffer.reset();

    // Make a new framebuffer so we can read back the texture.
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Flush via ReadPixels and check red was drawn.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    ASSERT_GL_NO_ERROR();
}

// This test was made to reproduce a specific issue with our Vulkan backend where were releasing
// buffers too early. The test has 2 textures, we first create a texture and update it with
// multiple updates, but we don't use it right away, we instead draw using another texture
// then we bind the first texture and draw with it.
TEST_P(SimpleStateChangeTest, DynamicAllocationOfMemoryForTextures)
{
    constexpr int kSize = 64;

    GLuint program = get2DTexturedQuadProgram();
    glUseProgram(program);

    std::vector<GLColor> greenPixels(kSize * kSize, GLColor::green);
    std::vector<GLColor> redPixels(kSize * kSize, GLColor::red);
    GLTexture texture1;
    glBindTexture(GL_TEXTURE_2D, texture1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kSize, kSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    for (int i = 0; i < 100; i++)
    {
        // We do this a lot of time to make sure we use multiple buffers in the vulkan backend.
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, kSize, kSize, GL_RGBA, GL_UNSIGNED_BYTE,
                        greenPixels.data());
    }
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    ASSERT_GL_NO_ERROR();

    GLTexture texture2;
    glBindTexture(GL_TEXTURE_2D, texture2);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, redPixels.data());
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    // Setup the vertex array to draw a quad.
    GLint positionLocation = glGetAttribLocation(program, "position");
    setupQuadVertexBuffer(1.0f, 1.0f);
    glVertexAttribPointer(positionLocation, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(positionLocation);

    // Draw quad with texture 2 while texture 1 has "staged" changes that have not been flushed yet.
    glBindTexture(GL_TEXTURE_2D, texture2);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // If we now try to draw with texture1, we should trigger the issue.
    glBindTexture(GL_TEXTURE_2D, texture1);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    ASSERT_GL_NO_ERROR();

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
}

// Tests deleting a Framebuffer that is in use.
TEST_P(SimpleStateChangeTest, RedefineFramebufferInUse)
{
    constexpr int kSize = 16;

    // Create a simple framebuffer.
    GLTexture texture;
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kSize, kSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    GLFramebuffer framebuffer;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    glViewport(0, 0, kSize, kSize);

    // Draw red to the framebuffer.
    simpleDrawWithColor(GLColor::red);

    // Change the framebuffer while the call is in flight to a new texture.
    GLTexture otherTexture;
    glBindTexture(GL_TEXTURE_2D, otherTexture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kSize, kSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);

    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, otherTexture, 0);
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    // Draw green to the framebuffer. Verify the color.
    simpleDrawWithColor(GLColor::green);
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);

    // Make a new framebuffer so we can read back the first texture and verify red.
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
    ASSERT_GL_NO_ERROR();
}

// Tests that redefining a Framebuffer Texture Attachment works as expected.
TEST_P(SimpleStateChangeTest, RedefineFramebufferTexture)
{
    GLFramebuffer framebuffer;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);

    // Bind a simple 8x8 texture to the framebuffer, draw red.
    GLTexture texture;
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 8, 8, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);

    glViewport(0, 0, 8, 8);
    simpleDrawWithColor(GLColor::red);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red) << "first draw should be red";

    // Redefine the texture to 32x32, draw green. Verify we get what we expect.
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    glViewport(0, 0, 32, 32);
    simpleDrawWithColor(GLColor::green);
    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green) << "second draw should be green";
}

// Validates disabling cull face really disables it.
TEST_P(SimpleStateChangeTest, EnableAndDisableCullFace)
{
    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());
    glUseProgram(program);

    glClear(GL_COLOR_BUFFER_BIT);
    glEnable(GL_CULL_FACE);

    glCullFace(GL_FRONT);

    drawQuad(program.get(), essl1_shaders::PositionAttrib(), 0.0f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::transparentBlack);

    // Disable cull face and redraw, then make sure we have the quad drawn.
    glDisable(GL_CULL_FACE);

    drawQuad(program.get(), essl1_shaders::PositionAttrib(), 0.0f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);
}

TEST_P(SimpleStateChangeTest, ScissorTest)
{
    // This test validates this order of state changes:
    // 1- Set scissor but don't enable it, validate its not used.
    // 2- Enable it and validate its working.
    // 3- Disable the scissor validate its not used anymore.

    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());

    glClear(GL_COLOR_BUFFER_BIT);

    // Set the scissor region, but don't enable it yet.
    glScissor(getWindowWidth() / 4, getWindowHeight() / 4, getWindowWidth() / 2,
              getWindowHeight() / 2);

    // Fill the whole screen with a quad.
    drawQuad(program.get(), essl1_shaders::PositionAttrib(), 0.0f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    // Test outside, scissor isnt enabled so its red.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Test inside, red of the fragment shader.
    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);

    // Clear everything and start over with the test enabled.
    glClear(GL_COLOR_BUFFER_BIT);
    glEnable(GL_SCISSOR_TEST);

    drawQuad(program.get(), essl1_shaders::PositionAttrib(), 0.0f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    // Test outside the scissor test, pitch black.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::transparentBlack);

    // Test inside, red of the fragment shader.
    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);

    // Now disable the scissor test, do it again, and verify the region isn't used
    // for the scissor test.
    glDisable(GL_SCISSOR_TEST);

    // Clear everything and start over with the test enabled.
    glClear(GL_COLOR_BUFFER_BIT);

    drawQuad(program.get(), essl1_shaders::PositionAttrib(), 0.0f, 1.0f, true);

    ASSERT_GL_NO_ERROR();

    // Test outside, scissor isnt enabled so its red.
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::red);

    // Test inside, red of the fragment shader.
    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 2, getWindowHeight() / 2, GLColor::red);
}

// This test validates we are able to change the valid of a uniform dynamically.
TEST_P(SimpleStateChangeTest, UniformUpdateTest)
{
    constexpr char kPositionUniformVertexShader[] = R"(
precision mediump float;
attribute vec2 position;
uniform vec2 uniPosModifier;
void main()
{
    gl_Position = vec4(position + uniPosModifier, 0, 1);
})";

    ANGLE_GL_PROGRAM(program, kPositionUniformVertexShader, essl1_shaders::fs::UniformColor());
    glUseProgram(program);

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    GLint posUniformLocation = glGetUniformLocation(program, "uniPosModifier");
    ASSERT_NE(posUniformLocation, -1);
    GLint colorUniformLocation = glGetUniformLocation(program, essl1_shaders::ColorUniform());
    ASSERT_NE(colorUniformLocation, -1);

    // draw a red quad to the left side.
    glUniform2f(posUniformLocation, -0.5, 0.0);
    glUniform4f(colorUniformLocation, 1.0, 0.0, 0.0, 1.0);
    drawQuad(program.get(), "position", 0.0f, 0.5f, true);

    // draw a green quad to the right side.
    glUniform2f(posUniformLocation, 0.5, 0.0);
    glUniform4f(colorUniformLocation, 0.0, 1.0, 0.0, 1.0);
    drawQuad(program.get(), "position", 0.0f, 0.5f, true);

    ASSERT_GL_NO_ERROR();

    // Test the center of the left quad. Should be red.
    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 4, getWindowHeight() / 2, GLColor::red);

    // Test the center of the right quad. Should be green.
    EXPECT_PIXEL_COLOR_EQ(getWindowWidth() / 4 * 3, getWindowHeight() / 2, GLColor::green);
}

// Tests that changing the storage of a Renderbuffer currently in use by GL works as expected.
TEST_P(SimpleStateChangeTest, RedefineRenderbufferInUse)
{
    GLRenderbuffer renderbuffer;
    glBindRenderbuffer(GL_RENDERBUFFER, renderbuffer);
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 16, 16);

    GLFramebuffer framebuffer;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer);
    glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffer);

    ASSERT_GL_NO_ERROR();
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ANGLE_GL_PROGRAM(program, kSimpleVertexShader, kSimpleFragmentShader);
    GLint colorLoc = glGetAttribLocation(program, "color");
    ASSERT_NE(-1, colorLoc);

    // Set up and draw red to the left half the screen.
    std::vector<GLColor> redData(6, GLColor::red);
    GLBuffer vertexBufferRed;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBufferRed);
    glBufferData(GL_ARRAY_BUFFER, redData.size() * sizeof(GLColor), redData.data(), GL_STATIC_DRAW);
    glVertexAttribPointer(colorLoc, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);
    glEnableVertexAttribArray(colorLoc);

    glViewport(0, 0, 16, 16);
    drawQuad(program, "position", 0.5f, 1.0f, true);

    // Immediately redefine the Renderbuffer.
    glRenderbufferStorage(GL_RENDERBUFFER, GL_RGBA8, 64, 64);

    // Set up and draw green to the right half of the screen.
    std::vector<GLColor> greenData(6, GLColor::green);
    GLBuffer vertexBufferGreen;
    glBindBuffer(GL_ARRAY_BUFFER, vertexBufferGreen);
    glBufferData(GL_ARRAY_BUFFER, greenData.size() * sizeof(GLColor), greenData.data(),
                 GL_STATIC_DRAW);
    glVertexAttribPointer(colorLoc, 4, GL_UNSIGNED_BYTE, GL_TRUE, 0, nullptr);
    glEnableVertexAttribArray(colorLoc);

    glViewport(0, 0, 64, 64);
    drawQuad(program, "position", 0.5f, 1.0f, true);

    ASSERT_GL_NO_ERROR();
    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
}

// Validate that we can draw -> change frame buffer size -> draw and we'll be rendering
// at the full size of the new framebuffer.
TEST_P(SimpleStateChangeTest, ChangeFramebufferSizeBetweenTwoDraws)
{
    constexpr size_t kSmallTextureSize = 2;
    constexpr size_t kBigTextureSize   = 4;

    // Create 2 textures, one of 2x2 and the other 4x4
    GLTexture texture1;
    glBindTexture(GL_TEXTURE_2D, texture1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kSmallTextureSize, kSmallTextureSize, 0, GL_RGBA,
                 GL_UNSIGNED_BYTE, nullptr);
    ASSERT_GL_NO_ERROR();

    GLTexture texture2;
    glBindTexture(GL_TEXTURE_2D, texture2);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kBigTextureSize, kBigTextureSize, 0, GL_RGBA,
                 GL_UNSIGNED_BYTE, nullptr);
    ASSERT_GL_NO_ERROR();

    // A framebuffer for each texture to draw on.
    GLFramebuffer framebuffer1;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer1);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture1, 0);
    ASSERT_GL_NO_ERROR();
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    GLFramebuffer framebuffer2;
    glBindFramebuffer(GL_FRAMEBUFFER, framebuffer2);
    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture2, 0);
    ASSERT_GL_NO_ERROR();
    ASSERT_GLENUM_EQ(GL_FRAMEBUFFER_COMPLETE, glCheckFramebufferStatus(GL_FRAMEBUFFER));

    ANGLE_GL_PROGRAM(program, essl1_shaders::vs::Simple(), essl1_shaders::fs::UniformColor());
    glUseProgram(program);
    GLint uniformLocation = glGetUniformLocation(program