[PR] Support to post-process on GPU with MetalCamera

[tucan9389]

Super thanks @jsharp83 for your MetalCamera

Related Issue

• 5

Changed

• Make post-processing on real-time segmentation extremely fast
  • AS-IS(CPU): > 240 ms (iPhone 11 Pro)
  • TO-BE(GPU): < 1 ms (iPhone 11 Pro)
• The main logic during generating textures:
  1. Get current pixelbuffer from camera
  2. Inference the pixelbuffer and get a segmentation map
  3. Generate a texture from the pixelbuffer (cameraTexture) https://github.com/tucan9389/SemanticSegmentation-CoreML/pull/7#discussion_r524046755
  4. Generate a texture from the segmentation map (segmentaitonTexture) https://github.com/tucan9389/SemanticSegmentation-CoreML/pull/7#discussion_r524047448
  5. Merge the textures and make a texture (overlayedTexture) https://github.com/tucan9389/SemanticSegmentation-CoreML/pull/7#discussion_r524047448
  6. Assign the overlayedTexture to metalVideoPreview: MetalVideoView
  7. Draw the overlayedTexture texture

PR Points

• Add LiveMetalCameraViewController post-processing with MetalKit
• Support extremely fast post-process
  • Add MetalRenderingDevice.swift from MetalCamera
  • Add MetalVideoView.swift from MetalCamera
  • Add CameraTextureGenerater.swift from MetalCamera
  • Add SegmentationTextureGenerater.swift from MetalCamera
  • Add OverlayingTexturesGenerater.swift from MetalCamera
  • Add other utils and shader code from MetalCamera

Reference

• https://github.com/jsharp83/MetalCamera
• https://github.com/jsharp83/MetalCamera/blob/master/Example/MetalCamera/SegmentationSampleViewController.swift