《OpenGL ES 2.0 Programming Guide》第9章 “最简单的本地纹理显示”示例代码【C语言版】

由于《OpenGL ES 2.0 Programming Guide》原书第9章并没有提供本地纹理加载的示例，都是程序生成的，遂自己实现了一份C语言版本的，希望能够帮助到同样喜欢OpenGL ES 2.0的同学。

废话不多说，直接上代码：

  

   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      #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;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      ///
     
    
   

    

     

    
    

     

      // 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 )
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    char *fileName = "D:/Projects/Visual Studio 2012/OpenGL_Demo/opengles-book-samples-master/Windows/Chapter_9/Simple_Texture2D/Fieldstone.tga";
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          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 ();
     
    
   

    

     

    
    

     

          userData->textureId = LoadTexture(fileName);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    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", 512, 512, ES_WINDOW_RGB );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    if ( !Init ( &esContext ) )
     
    
   

    

     

    
    

     
        return 0;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    esRegisterDrawFunc ( &esContext, Draw );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    esMainLoop ( &esContext );
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    ShutDown ( &esContext );
     
    
   

    

     

    
    

     

      }
     
    
  
 

文章来源: panda1234lee.blog.csdn.net，作者：panda1234lee，版权归原作者所有，如需转载，请联系作者。

原文链接：panda1234lee.blog.csdn.net/article/details/52406190