我无法从与CoreGraphics在透明背景OpenGL上下文渲染的图像。CoreGraphics在图像从OpenGL的渲染具有黑色背景
渲染图像具有黑色背景。
这是抽奖代码
GLint default_frame_buffer = 0;
glGetIntegerv(GL_FRAMEBUFFER_BINDING, &default_frame_buffer);
if (default_frame_buffer == 0) {
target = createBMGLRenderTarget(width, height);
setFiltering(target, BMGL_BilinearFiltering);
glBindFramebuffer(GL_FRAMEBUFFER, target->framebuffer);
}
glViewport(0, 0, width, height);
if (background) {
CGFloat red, green, blue, alpha;
[background getRed:&red green:&green blue:&blue alpha:&alpha];
glClearColor(red, green, blue, alpha);
} else {
glClearColor(0.f, 0.f, 0.f, 0.f);
}
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
drawer.draw()
glFlush();
glFinish();
GLubyte *data = (GLubyte *)malloc(width * height * 4);
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, width * height * 4, NULL);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGImageRef imgRef = CGImageCreate(width, height, 8, 32, width * 4, colorspace, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast, ref, NULL, NO, kCGRenderingIntentDefault);
UIGraphicsBeginImageContextWithOptions(size, YES, 0.0);
CGContextRef cgContext = UIGraphicsGetCurrentContext();
CGContextSetBlendMode(cgContext, kCGBlendModeCopy);
CGContextDrawImage(cgContext, CGRectMake(0, 0, size.width, size.height), imgRef);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
free(data);
CGDataProviderRelease(ref);
CGColorSpaceRelease(colorspace);
CGImageRelease(imgRef);
我试图专门设置不透明的虚假以及不同的混合模式,但它仍然增加了一个黑色的背景,原来的清晰的图像。我能够设置GLKView有一个透明的背景,但渲染图像,然后绘制其内容为CGImage不起作用。
有谁知道这是为什么?
也许这有助于:https://stackoverflow.com/questions/5283670/displaying-an-eaglview-with-transparent-background-on-a-uiimageview –
谢谢,我能够渲染具有透明背景GLKView,只是在将其渲染到另一个背景时背景是黑色的。我也不能简单地从GLKView层次结构中获取图像,因为我想排除其他动画。 – jarryd