在IPhone中把文字转换为一张图片

- ( GLuint )setupTextTexture:( NSString *)text

{

    //0

    CGPoint position = CGPointMake(0,0);

    // Make a UILabel with the string

    UIFont *font = [UIFont fontWithName:@"Georgia" size:12];

    CGRect screenBounds = [ [ UIScreen mainScreen ] bounds ];

    CGSize maximumSize = CGSizeMake(screenBounds.size.width-50, 9999);

    CGSize size = [text sizeWithFont:font

                   constrainedToSize:maximumSize

                       lineBreakMode:UILineBreakModeClip];

//    CGSize size = [text sizeWithFont:font forWidth:12 lineBreakMode:UILineBreakModeClip];

    CGRect frame;

    frame.origin = position;

    frame.size = size;

    UILabel *label = [[UILabel alloc]initWithFrame:CGRectMake(0.0f, 10.0f, size.width, size.height)];

    label.backgroundColor = [UIColor colorWithRed:1 green:1 blue:1 alpha:1];

    label.text = text;

    label.textColor = [UIColor colorWithRed:0 green:0 blue:0 alpha:1];

    label.font = font;

    

    // Make a UIImage with the UILabel

    UIGraphicsBeginImageContext(label.frame.size);

    [[label layer] renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *layerImage = UIGraphicsGetImageFromCurrentImageContext();

    

//    NSString  *pngPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Test111.png"];

//    NSData *imageData = UIImagePNGRepresentation(layerImage);

//    [imageData writeToFile:pngPath atomically:YES];

    

    UIGraphicsEndImageContext();

    // 1

    CGImageRef spriteImage = layerImage.CGImage;

    if (!spriteImage) {

        NSLog(@"Failed to setup text image %@", text);

        exit(1);

    }

    

    // 2

    size_t width = CGImageGetWidth(spriteImage);

    size_t height = CGImageGetHeight(spriteImage);

    

    GLubyte * spriteData = (GLubyte *) calloc(width*height*4, sizeof(GLubyte));

    

    CGContextRef spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width*4,

                                                       CGImageGetColorSpace(spriteImage), kCGImageAlphaPremultipliedLast);

    

    // 3

    CGContextDrawImage(spriteContext, CGRectMake(0, 0, width, height), spriteImage);

    

    CGContextRelease(spriteContext);

    

    // 4

    GLuint texName;

    glGenTextures(1, &texName);

    glBindTexture(GL_TEXTURE_2D, texName);

    

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, spriteData);

    

    free(spriteData);

    

    return texName;

}