| // |
| // Modified from Simple_Texture2D, found in: |
| // |
| // Book: OpenGL(R) ES 2.0 Programming Guide |
| // Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner |
| // ISBN-10: 0321502795 |
| // ISBN-13: 9780321502797 |
| // Publisher: Addison-Wesley Professional |
| // URLs: http://safari.informit.com/9780321563835 |
| // http://www.opengles-book.com |
| // |
| |
| // MultipleRenderTargets.c |
| // |
| // This is a simple example that shows how to use multiple render |
| // targets in GLES 2.0 using EXT_draw_buffers. The example |
| // draws to three render targets and displays |
| // them together in a final pass. |
| // |
| #include <stdlib.h> |
| #include "esUtil.h" |
| |
| PFNGLDRAWBUFFERSEXTPROC glDrawBuffersEXT; |
| |
| typedef struct |
| { |
| // Handle to a program object |
| GLuint programObjectMRT; |
| GLuint programObject; |
| |
| // Attribute locations |
| GLint positionLoc; |
| GLint texCoordLoc; |
| |
| // Sampler location |
| GLint samplerLoc; |
| |
| // Texture handle |
| GLuint textureId; |
| |
| // Framebuffer object handle |
| GLuint framebuffer; |
| |
| // Framebuffer color attachments |
| GLuint framebufferTextures[4]; |
| |
| } UserData; |
| |
| /// |
| // Create a simple 2x2 texture image with four different colors |
| // |
| GLuint CreateSimpleTexture2D( ) |
| { |
| // Texture object handle |
| GLuint textureId; |
| |
| // 2x2 Image, 3 bytes per pixel (R, G, B) |
| GLubyte pixels[4 * 3] = |
| { |
| 255, 0, 0, // Red |
| 0, 255, 0, // Green |
| 0, 0, 255, // Blue |
| 255, 255, 0 // Yellow |
| }; |
| |
| // Use tightly packed data |
| glPixelStorei ( GL_UNPACK_ALIGNMENT, 1 ); |
| |
| // Generate a texture object |
| glGenTextures ( 1, &textureId ); |
| |
| // Bind the texture object |
| glBindTexture ( GL_TEXTURE_2D, textureId ); |
| |
| // Load the texture |
| glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, 2, 2, 0, GL_RGB, GL_UNSIGNED_BYTE, pixels ); |
| |
| // Set the filtering mode |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST ); |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST ); |
| |
| return textureId; |
| |
| } |
| |
| |
| /// |
| // Initialize the shader and program object |
| // |
| int Init ( ESContext *esContext ) |
| { |
| UserData *userData = (UserData*)esContext->userData; |
| GLbyte vShaderStr[] = |
| "attribute vec4 a_position; \n" |
| "attribute vec2 a_texCoord; \n" |
| "varying vec2 v_texCoord; \n" |
| "void main() \n" |
| "{ \n" |
| " gl_Position = a_position; \n" |
| " v_texCoord = a_texCoord; \n" |
| "} \n"; |
| |
| GLbyte fMultiShaderStr[] = |
| "#extension GL_EXT_draw_buffers : enable \n" |
| "precision mediump float; \n" |
| "varying vec2 v_texCoord; \n" |
| "uniform sampler2D s_texture; \n" |
| "void main() \n" |
| "{ \n" |
| " vec4 color = texture2D( s_texture, v_texCoord ); \n" |
| " gl_FragData[0] = color; \n" |
| " gl_FragData[1] = vec4(1.0, 1.0, 1.0, 1.0) - color.brga;\n" |
| " gl_FragData[2] = vec4(0.2, 1.0, 0.5, 1.0) * color.gbra;\n" |
| " gl_FragData[3] = color.rrra; \n" |
| "} \n"; |
| |
| GLbyte fShaderStr[] = |
| "precision mediump float; \n" |
| "varying vec2 v_texCoord; \n" |
| "uniform sampler2D s_texture; \n" |
| "void main() \n" |
| "{ \n" |
| " vec4 color = texture2D( s_texture, v_texCoord ); \n" |
| " gl_FragColor = color; \n" |
| "} \n"; |
| |
| int i; |
| |
| // Check EXT_draw_buffers is supported |
| if (strstr(glGetString(GL_EXTENSIONS), "GL_EXT_draw_buffers") == 0) |
| { |
| return FALSE; |
| } |
| |
| // Retrieve the address of glDrawBuffersEXT from EGL |
| glDrawBuffersEXT = (PFNGLDRAWBUFFERSEXTPROC)eglGetProcAddress("glDrawBuffersEXT"); |
| |
| // Load the shaders and get a linked program object |
| userData->programObject = esLoadProgram ( (const char*)vShaderStr, (const char*)fShaderStr ); |
| |
| userData->programObjectMRT = esLoadProgram ( (const char*)vShaderStr, (const char*)fMultiShaderStr ); |
| |
| // Get the attribute locations |
| userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" ); |
| userData->texCoordLoc = glGetAttribLocation ( userData->programObject, "a_texCoord" ); |
| |
| // Get the sampler location |
| userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" ); |
| |
| // Load the texture |
| userData->textureId = CreateSimpleTexture2D (); |
| |
| glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f ); |
| |
| // Initialize the user framebuffer |
| glGenFramebuffers(1, &userData->framebuffer); |
| glGenTextures(4, userData->framebufferTextures); |
| |
| glBindFramebuffer(GL_FRAMEBUFFER, userData->framebuffer); |
| |
| for (i = 0; i < 4; i++) |
| { |
| // Create textures for the four color attachments |
| glBindTexture(GL_TEXTURE_2D, userData->framebufferTextures[i]); |
| glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, esContext->width, esContext->height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); |
| glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); |
| glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0_EXT + i, GL_TEXTURE_2D, userData->framebufferTextures[i], 0); |
| } |
| |
| glBindTexture(GL_TEXTURE_2D, 0); |
| |
| return TRUE; |
| } |
| |
| /// |
| // Draw a triangle using the shader pair created in Init() |
| // |
| void Draw ( ESContext *esContext ) |
| { |
| UserData *userData = (UserData*)esContext->userData; |
| GLfloat vVertices[] = { -0.8f, 0.8f, 0.0f, // Position 0 |
| 0.0f, 0.0f, // TexCoord 0 |
| -0.8f, -0.8f, 0.0f, // Position 1 |
| 0.0f, 1.0f, // TexCoord 1 |
| 0.8f, -0.8f, 0.0f, // Position 2 |
| 1.0f, 1.0f, // TexCoord 2 |
| 0.8f, 0.8f, 0.0f, // Position 3 |
| 1.0f, 0.0f // TexCoord 3 |
| }; |
| GLushort indices[] = { 0, 1, 2, 0, 2, 3 }; |
| |
| GLenum drawBuffers[] = { GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT, GL_COLOR_ATTACHMENT2_EXT, GL_COLOR_ATTACHMENT3_EXT }; |
| |
| // Enable drawing to the four color attachments of the user framebuffer |
| glBindFramebuffer(GL_FRAMEBUFFER, userData->framebuffer); |
| glDrawBuffersEXT(4, drawBuffers); |
| |
| // Set the viewport |
| glViewport ( 0, 0, esContext->width, esContext->height ); |
| |
| // Clear the color buffer |
| glClear ( GL_COLOR_BUFFER_BIT ); |
| |
| // Use the program object |
| glUseProgram ( userData->programObjectMRT ); |
| |
| // Load the vertex position |
| glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT, |
| GL_FALSE, 5 * sizeof(GLfloat), vVertices ); |
| // Load the texture coordinate |
| glVertexAttribPointer ( userData->texCoordLoc, 2, GL_FLOAT, |
| GL_FALSE, 5 * sizeof(GLfloat), &vVertices[3] ); |
| |
| glEnableVertexAttribArray ( userData->positionLoc ); |
| glEnableVertexAttribArray ( userData->texCoordLoc ); |
| |
| // Bind the texture |
| glActiveTexture ( GL_TEXTURE0 ); |
| glBindTexture ( GL_TEXTURE_2D, userData->textureId ); |
| |
| // Set the sampler texture unit to 0 |
| glUniform1i ( userData->samplerLoc, 0 ); |
| |
| // Draw the textured quad to the four render targets |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| // Enable the default framebuffer and single textured drawing |
| glBindFramebuffer(GL_FRAMEBUFFER, 0); |
| glUseProgram ( userData->programObject ); |
| |
| // Draw the four textured quads to a separate region in the viewport |
| glBindTexture( GL_TEXTURE_2D, userData->framebufferTextures[0]); |
| glViewport ( 0, 0, esContext->width/2, esContext->height/2 ); |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| glBindTexture( GL_TEXTURE_2D, userData->framebufferTextures[1]); |
| glViewport ( esContext->width/2, 0, esContext->width/2, esContext->height/2 ); |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| glBindTexture( GL_TEXTURE_2D, userData->framebufferTextures[2]); |
| glViewport ( 0, esContext->height/2, esContext->width/2, esContext->height/2 ); |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| glBindTexture( GL_TEXTURE_2D, userData->framebufferTextures[3]); |
| glViewport ( esContext->width/2, esContext->height/2, esContext->width/2, esContext->height/2 ); |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface ); |
| } |
| |
| /// |
| // Cleanup |
| // |
| void ShutDown ( ESContext *esContext ) |
| { |
| UserData *userData = (UserData*)esContext->userData; |
| |
| glDeleteTextures(4, userData->framebufferTextures); |
| |
| glDeleteFramebuffers(1, &userData->framebuffer); |
| |
| // Delete texture object |
| glDeleteTextures ( 1, &userData->textureId ); |
| |
| // Delete program object |
| glDeleteProgram ( userData->programObject ); |
| |
| eglDestroyContext(esContext->eglDisplay, esContext->eglContext); |
| eglDestroySurface(esContext->eglDisplay, esContext->eglSurface); |
| eglTerminate(esContext->eglDisplay); |
| } |
| |
| |
| int main ( int argc, char *argv[] ) |
| { |
| ESContext esContext; |
| UserData userData; |
| |
| esInitContext ( &esContext ); |
| esContext.userData = &userData; |
| |
| esCreateWindow ( &esContext, TEXT("Multiple Render Targets"), 320, 240, ES_WINDOW_RGB ); |
| |
| if ( !Init ( &esContext ) ) |
| return 0; |
| |
| esRegisterDrawFunc ( &esContext, Draw ); |
| |
| esMainLoop ( &esContext ); |
| |
| ShutDown ( &esContext ); |
| } |