将文本叠加为纹理iOS

Question

我尝试使用以下代码段将文本叠加为纹理：

UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 30)];
myLabel.text = @"Hello world!";
myLabel.font = [UIFont fontWithName:@"Helvetica" size:18];
myLabel.textColor = [UIColor colorWithRed:0/255.0 green:0/255.0 blue:0/255.0 alpha:1];   
myLabel.backgroundColor = [UIColor clearColor];

UIGraphicsBeginImageContext(myLabel.bounds.size);

CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0, 30);

CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);

[myLabel.layer renderInContext:UIGraphicsGetCurrentContext()];

UIImage *layerImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

但它不可见。为了使用OpenGL将图像显示为纹理，我尝试了以下代码片段：

/// here image is the layerImage created in above piece of code                                      
GLuint width = CGImageGetWidth(image.CGImage);
GLuint height = CGImageGetHeight(image.CGImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
void *imageData = malloc( height * width * 4 );
CGContextRef context = CGBitmapContextCreate( imageData, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big );
CGColorSpaceRelease( colorSpace );
CGContextClearRect( context, CGRectMake( 0, 0, width, height ) );
CGContextTranslateCTM( context, 0, height - height );
CGContextDrawImage( context, CGRectMake( 0, 0, width, height ), image.CGImage );

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

CGContextRelease(context);

free(imageData);
[image release];
[texData release];

但是图像没有显示出来。是否还有其他方法可以在ios中使用OpenGL将文本显示为纹理？