问从MTLTextures摄像机流生成mipmaped

EN

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
  CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

  id<MTLTexture> texture = nil;

  {
    size_t width = CVPixelBufferGetWidth(pixelBuffer);
    size_t height = CVPixelBufferGetHeight(pixelBuffer);

    MTLPixelFormat pixelFormat = MTLPixelFormatBGRA8Unorm;

    CVMetalTextureRef metalTextureRef = NULL;

    CVReturn status = CVMetalTextureCacheCreateTextureFromImage(NULL, _textureCache, pixelBuffer, NULL, pixelFormat, width, height, 0, &metalTextureRef);
    if(status == kCVReturnSuccess)
    {
     texture = CVMetalTextureGetTexture(metalTextureRef);

     if (self.delegate){

        [self.delegate textureUpdated:texture];
      }
      CFRelease(metalTextureRef);
    }
  }
}

CVMetalTextureCacheCreateTextureFromImage(NULL, _textureCache, pixelBuffer, NULL, pixelFormat, width, height, 0, &metalTextureRef);