iPhone OpenGL ES加载纹理的方法

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//加载一张名为xiezi.png的图片纹理

- (void)loadTexture {

    CGImageRef textureImage = [UIImage imageNamed:@"xiezi.png"].CGImage;
    if (textureImage == nil) {
        NSLog(@"Failed to load texture image");
       return;
    }

    NSInteger texWidth = CGImageGetWidth(textureImage);
    NSInteger texHeight = CGImageGetHeight(textureImage);

   GLubyte *textureData = (GLubyte *)malloc(texWidth * texHeight * 4);

    CGContextRef textureContext = CGBitmapContextCreate(textureData,
                                                        texWidth, texHeight,
                                                        8, texWidth * 4,
                                                        CGImageGetColorSpace(textureImage),
                                                        kCGImageAlphaPremultipliedLast);
   CGContextDrawImage(textureContext, CGRectMake(0.0, 0.0, (float)texWidth, (float)texHeight), textureImage);
   CGContextRelease(textureContext);

   glGenTextures(1, &textures[0]);
   glBindTexture(GL_TEXTURE_2D, textures[0]);
   glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, texWidth, texHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, textureData);

   free(textureData);

   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
   glEnable(GL_TEXTURE_2D);

}

其中，纹理缓冲区定义为：

GLuint textures[1];

加载纹理的方法中需要用到CoreGraphics框架，不然编译会出错。