裁剪UIImage以与GLKTextureLoader一起使用

Question

我试图从UIImage中裁剪一个区域以与GLKTextureLoader一起使用.我可以使用UIImage直接设置纹理,如下所示:

- (void)setTextureImage:(UIImage *)image
{
    NSError *error;

    texture = [GLKTextureLoader textureWithCGImage:image.CGImage options:nil error:&error];

    if(error)
    {
        NSLog(@"Texture Error:%@", error);
    } else {
        self.textureCoordinates[0] = GLKVector2Make(1.0f, 1.0f);
        self.textureCoordinates[1] = GLKVector2Make(1.0f, 0);
        self.textureCoordinates[2] = GLKVector2Make(0, 0);
        self.textureCoordinates[3] = GLKVector2Make(0, 1.0f);
    }
}

但是,如果我尝试以这种方式裁剪图像:

- (void)setTextureImage:(UIImage *)image
{
    NSError *error;

    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, CGRectMake(0.0, 64.0f, 64.0f, 64.0f));
    texture = [GLKTextureLoader textureWithCGImage:imageRef options:nil error:&error];

    if(error)
    {
        NSLog(@"[SF] Texture Error:%@", error);
    } else {
        self.textureCoordinates[0] = GLKVector2Make(1.0f, 1.0f);
        self.textureCoordinates[1] = GLKVector2Make(1.0f, 0);
        self.textureCoordinates[2] = GLKVector2Make(0, 0);
        self.textureCoordinates[3] = GLKVector2Make(0, 1.0f);
    }
}

我收到此错误:

Texture Error:Error Domain=GLKTextureLoaderErrorDomain Code=12 "The operation couldn’t be completed. (GLKTextureLoaderErrorDomain error 12.)" UserInfo=0x6a6b550 {GLKTextureLoaderErrorKey=Image decoding failed}

如何将UIImage的一部分用作GLKTextureLoader的纹理？

Answer 1

最后我让它与UIImagePNGRepresentation合作,我现在只学习OpenGL/GLKit - 所以不是专家,但我猜测CGImage缺少一些颜色空间或纹理所需的其他数据.

- (void)setTextureImage:(UIImage *)image withFrame:(CGRect)rect
{
    NSError *error;

    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, rect);
    image = [UIImage imageWithData:UIImagePNGRepresentation([UIImage imageWithCGImage:imageRef])];

    texture = [GLKTextureLoader textureWithCGImage:image.CGImage options:nil error:&error];

    if(error)
    {
        NSLog(@"[SF] Texture Error:%@", error);
    } else {
        self.textureCoordinates[0] = GLKVector2Make(1.0f, 1.0f);
        self.textureCoordinates[1] = GLKVector2Make(1.0f, 0);
        self.textureCoordinates[2] = GLKVector2Make(0, 0);
        self.textureCoordinates[3] = GLKVector2Make(0, 1.0f);
    }
}