| // |
| // 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 |
| // |
| |
| // MultiTexture.c |
| // |
| // This is an example that draws a quad with a basemap and |
| // lightmap to demonstrate multitexturing. |
| // |
| #include <stdlib.h> |
| #include "esUtil.h" |
| |
| typedef struct |
| { |
| // Handle to a program object |
| GLuint programObject; |
| |
| // Attribute locations |
| GLint positionLoc; |
| GLint texCoordLoc; |
| |
| // Sampler locations |
| GLint baseMapLoc; |
| GLint lightMapLoc; |
| |
| // Texture handle |
| GLuint baseMapTexId; |
| GLuint lightMapTexId; |
| |
| } UserData; |
| |
| |
| /// |
| // Load texture from disk |
| // |
| GLuint LoadTexture ( char *fileName ) |
| { |
| int width, |
| height; |
| char *buffer = esLoadTGA ( fileName, &width, &height ); |
| GLuint texId; |
| |
| if ( buffer == NULL ) |
| { |
| esLogMessage ( "Error loading (%s) image.\n", fileName ); |
| return 0; |
| } |
| |
| glGenTextures ( 1, &texId ); |
| glBindTexture ( GL_TEXTURE_2D, texId ); |
| |
| glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer ); |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE ); |
| glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE ); |
| |
| free ( buffer ); |
| |
| return texId; |
| } |
| |
| |
| |
| /// |
| // Initialize the shader and program object |
| // |
| int Init ( ESContext *esContext ) |
| { |
| 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 fShaderStr[] = |
| "precision mediump float; \n" |
| "varying vec2 v_texCoord; \n" |
| "uniform sampler2D s_baseMap; \n" |
| "uniform sampler2D s_lightMap; \n" |
| "void main() \n" |
| "{ \n" |
| " vec4 baseColor; \n" |
| " vec4 lightColor; \n" |
| " \n" |
| " baseColor = texture2D( s_baseMap, v_texCoord ); \n" |
| " lightColor = texture2D( s_lightMap, v_texCoord ); \n" |
| " gl_FragColor = baseColor * (lightColor + 0.25); \n" |
| "} \n"; |
| |
| // Load the shaders and get a linked program object |
| userData->programObject = esLoadProgram ( vShaderStr, fShaderStr ); |
| |
| // Get the attribute locations |
| userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" ); |
| userData->texCoordLoc = glGetAttribLocation ( userData->programObject, "a_texCoord" ); |
| |
| // Get the sampler location |
| userData->baseMapLoc = glGetUniformLocation ( userData->programObject, "s_baseMap" ); |
| userData->lightMapLoc = glGetUniformLocation ( userData->programObject, "s_lightMap" ); |
| |
| // Load the textures |
| userData->baseMapTexId = LoadTexture ( "basemap.tga" ); |
| userData->lightMapTexId = LoadTexture ( "lightmap.tga" ); |
| |
| if ( userData->baseMapTexId == 0 || userData->lightMapTexId == 0 ) |
| return FALSE; |
| |
| glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f ); |
| return TRUE; |
| } |
| |
| /// |
| // Draw a triangle using the shader pair created in Init() |
| // |
| void Draw ( ESContext *esContext ) |
| { |
| UserData *userData = esContext->userData; |
| GLfloat vVertices[] = { -0.5f, 0.5f, 0.0f, // Position 0 |
| 0.0f, 0.0f, // TexCoord 0 |
| -0.5f, -0.5f, 0.0f, // Position 1 |
| 0.0f, 1.0f, // TexCoord 1 |
| 0.5f, -0.5f, 0.0f, // Position 2 |
| 1.0f, 1.0f, // TexCoord 2 |
| 0.5f, 0.5f, 0.0f, // Position 3 |
| 1.0f, 0.0f // TexCoord 3 |
| }; |
| GLushort indices[] = { 0, 1, 2, 0, 2, 3 }; |
| |
| // 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->programObject ); |
| |
| // 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 base map |
| glActiveTexture ( GL_TEXTURE0 ); |
| glBindTexture ( GL_TEXTURE_2D, userData->baseMapTexId ); |
| |
| // Set the base map sampler to texture unit to 0 |
| glUniform1i ( userData->baseMapLoc, 0 ); |
| |
| // Bind the light map |
| glActiveTexture ( GL_TEXTURE1 ); |
| glBindTexture ( GL_TEXTURE_2D, userData->lightMapTexId ); |
| |
| // Set the light map sampler to texture unit 1 |
| glUniform1i ( userData->lightMapLoc, 1 ); |
| |
| glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); |
| |
| eglSwapBuffers ( esContext->eglDisplay, esContext->eglSurface ); |
| } |
| |
| /// |
| // Cleanup |
| // |
| void ShutDown ( ESContext *esContext ) |
| { |
| UserData *userData = esContext->userData; |
| |
| // Delete texture object |
| glDeleteTextures ( 1, &userData->baseMapTexId ); |
| glDeleteTextures ( 1, &userData->lightMapTexId ); |
| |
| // Delete program object |
| glDeleteProgram ( userData->programObject ); |
| } |
| |
| |
| int main ( int argc, char *argv[] ) |
| { |
| ESContext esContext; |
| UserData userData; |
| |
| esInitContext ( &esContext ); |
| esContext.userData = &userData; |
| |
| esCreateWindow ( &esContext, TEXT("MultiTexture"), 320, 240, ES_WINDOW_RGB ); |
| |
| if ( !Init ( &esContext ) ) |
| return 0; |
| |
| esRegisterDrawFunc ( &esContext, Draw ); |
| |
| esMainLoop ( &esContext ); |
| |
| ShutDown ( &esContext ); |
| } |