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Diffstat (limited to 'third_party/gles2_book/Chapter_9/TextureWrap/TextureWrap.c')
| -rw-r--r-- | third_party/gles2_book/Chapter_9/TextureWrap/TextureWrap.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/third_party/gles2_book/Chapter_9/TextureWrap/TextureWrap.c b/third_party/gles2_book/Chapter_9/TextureWrap/TextureWrap.c new file mode 100644 index 0000000..2083819 --- /dev/null +++ b/third_party/gles2_book/Chapter_9/TextureWrap/TextureWrap.c @@ -0,0 +1,254 @@ +// +// 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 +// + +// TextureWrap.c +// +// This is an example that demonstrates the three texture +// wrap modes available on 2D textures +// +#include <stdlib.h> +#include "esUtil.h" + +typedef struct +{ + // Handle to a program object + GLuint programObject; + + // Attribute locations + GLint positionLoc; + GLint texCoordLoc; + + // Sampler location + GLint samplerLoc; + + // Offset location + GLint offsetLoc; + + // Texture handle + GLuint textureId; + +} UserData; + +/// +// Generate an RGB8 checkerboard image +// +GLubyte* GenCheckImage( int width, int height, int checkSize ) +{ + int x, + y; + GLubyte *pixels = malloc( width * height * 3 ); + + if ( pixels == NULL ) + return NULL; + + for ( y = 0; y < height; y++ ) + for ( x = 0; x < width; x++ ) + { + GLubyte rColor = 0; + GLubyte bColor = 0; + + if ( ( x / checkSize ) % 2 == 0 ) + { + rColor = 255 * ( ( y / checkSize ) % 2 ); + bColor = 255 * ( 1 - ( ( y / checkSize ) % 2 ) ); + } + else + { + bColor = 255 * ( ( y / checkSize ) % 2 ); + rColor = 255 * ( 1 - ( ( y / checkSize ) % 2 ) ); + } + + pixels[(y * height + x) * 3] = rColor; + pixels[(y * height + x) * 3 + 1] = 0; + pixels[(y * height + x) * 3 + 2] = bColor; + } + + return pixels; +} + +/// +// Create a mipmapped 2D texture image +// +GLuint CreateTexture2D( ) +{ + // Texture object handle + GLuint textureId; + int width = 256, + height = 256; + GLubyte *pixels; + + pixels = GenCheckImage( width, height, 64 ); + if ( pixels == NULL ) + return 0; + + // Generate a texture object + glGenTextures ( 1, &textureId ); + + // Bind the texture object + glBindTexture ( GL_TEXTURE_2D, textureId ); + + // Load mipmap level 0 + glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, width, height, + 0, GL_RGB, GL_UNSIGNED_BYTE, pixels ); + + // Set the filtering mode + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR ); + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR ); + + return textureId; + +} + + +/// +// Initialize the shader and program object +// +int Init ( ESContext *esContext ) +{ + UserData *userData = esContext->userData; + GLbyte vShaderStr[] = + "uniform float u_offset; \n" + "attribute vec4 a_position; \n" + "attribute vec2 a_texCoord; \n" + "varying vec2 v_texCoord; \n" + "void main() \n" + "{ \n" + " gl_Position = a_position; \n" + " gl_Position.x += u_offset;\n" + " v_texCoord = a_texCoord; \n" + "} \n"; + + GLbyte fShaderStr[] = + "precision mediump float; \n" + "varying vec2 v_texCoord; \n" + "uniform sampler2D s_texture; \n" + "void main() \n" + "{ \n" + " gl_FragColor = texture2D( s_texture, v_texCoord );\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->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" ); + + // Get the offset location + userData->offsetLoc = glGetUniformLocation( userData->programObject, "u_offset" ); + + // Load the texture + userData->textureId = CreateTexture2D (); + + 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[] = { -0.3f, 0.3f, 0.0f, 1.0f, // Position 0 + -1.0f, -1.0f, // TexCoord 0 + -0.3f, -0.3f, 0.0f, 1.0f, // Position 1 + -1.0f, 2.0f, // TexCoord 1 + 0.3f, -0.3f, 0.0f, 1.0f, // Position 2 + 2.0f, 2.0f, // TexCoord 2 + 0.3f, 0.3f, 0.0f, 1.0f, // Position 3 + 2.0f, -1.0f // 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, 4, GL_FLOAT, + GL_FALSE, 6 * sizeof(GLfloat), vVertices ); + // Load the texture coordinate + glVertexAttribPointer ( userData->texCoordLoc, 2, GL_FLOAT, + GL_FALSE, 6 * sizeof(GLfloat), &vVertices[4] ); + + 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 quad with repeat wrap mode + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT ); + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT ); + glUniform1f ( userData->offsetLoc, -0.7f ); + glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); + + // Draw quad with clamp to edge wrap mode + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE ); + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE ); + glUniform1f ( userData->offsetLoc, 0.0f ); + glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices ); + + // Draw quad with mirrored repeat + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT ); + glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT ); + glUniform1f ( userData->offsetLoc, 0.7f ); + 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->textureId ); + + // Delete program object + glDeleteProgram ( userData->programObject ); +} + + +int main ( int argc, char *argv[] ) +{ + ESContext esContext; + UserData userData; + + esInitContext ( &esContext ); + esContext.userData = &userData; + + esCreateWindow ( &esContext, "MipMap 2D", 640, 480, ES_WINDOW_RGB ); + + if ( !Init ( &esContext ) ) + return 0; + + esRegisterDrawFunc ( &esContext, Draw ); + + esMainLoop ( &esContext ); + + ShutDown ( &esContext ); +} |