Renamed gles_book_examples to gles2_book to make it shorter and more correct....

third_party/gles_book_examples/Chapter_9/Simple_Texture2D/Simple_Texture2D.c

-//
-// 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
-//
-
-// Simple_Texture2D.c
-//
-//    This is a simple example that draws a quad with a 2D
-//    texture image. The purpose of this example is to demonstrate 
-//    the basics of 2D texturing
-//
-#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;
-
-   // Texture handle
-   GLuint textureId;
-
-} 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 = 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_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" );
-
-   // Load the texture
-   userData->textureId = CreateSimpleTexture2D ();
-
-   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 texture
-   glActiveTexture ( GL_TEXTURE0 );
-   glBindTexture ( GL_TEXTURE_2D, userData->textureId );
-
-   // Set the sampler texture unit to 0
-   glUniform1i ( userData->samplerLoc, 0 );
-
-   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, "Simple Texture 2D", 320, 240, ES_WINDOW_RGB );
-   
-   if ( !Init ( &esContext ) )
-      return 0;
-
-   esRegisterDrawFunc ( &esContext, Draw );
-   
-   esMainLoop ( &esContext );
-
-   ShutDown ( &esContext );
-}