Multi-Sampling / Jagged Edges in Metal (iOS)

Question

I'm currently trying to draw graphics that will be animated using Metal in Swift. I successfully created one frame of my graphics. The graphics are simple, as you can see from this image. I cannot figure out how to make a multi-sample drawing. There are apparently very few references to Metal in general, especially regarding Swift syntax.

self.metalLayer = CAMetalLayer() self.metalLayer.device = self.device self.metalLayer.pixelFormat = .BGRA8Unorm self.metalLayer.framebufferOnly = true self.metalLayer.frame = self.view.frame self.view.layer.addSublayer(self.metalLayer) self.renderer = SunRenderer(device: self.device, frame: self.view.frame) let defaultLibrary = self.device.newDefaultLibrary() let fragmentProgram = defaultLibrary!.newFunctionWithName("basic_fragment") let vertexProgram = defaultLibrary!.newFunctionWithName("basic_vertex") let pipelineStateDescriptor = MTLRenderPipelineDescriptor() pipelineStateDescriptor.vertexFunction = vertexProgram pipelineStateDescriptor.fragmentFunction = fragmentProgram pipelineStateDescriptor.colorAttachments[0].pixelFormat = .BGRA8Unorm pipelineStateDescriptor.colorAttachments[0].blendingEnabled = true pipelineStateDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperation.Add pipelineStateDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperation.Add pipelineStateDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactor.SourceAlpha pipelineStateDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactor.SourceAlpha pipelineStateDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactor.OneMinusSourceAlpha pipelineStateDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactor.OneMinusSourceAlpha 

The question is how to smooth these ribs?

UPDATE:

So, I implemented the MultiSample texture and set sampleCount to 4. I don't notice any difference, so I suspect that I did something wrong.

COMPLETION:

So in the end, it seems like multithreaded work. Initially, I had vertices wrapping these "rays" with 0 alpha. This is a trick to make smoother edges. With these tops, multisampling did not improve the edges. When I go back to have 4 vertices per ray, multisampling has improved their edges.

 let defaultLibrary = self.device.newDefaultLibrary() let fragmentProgram = defaultLibrary!.newFunctionWithName("basic_fragment") let vertexProgram = defaultLibrary!.newFunctionWithName("basic_vertex") let pipelineStateDescriptor = MTLRenderPipelineDescriptor() pipelineStateDescriptor.vertexFunction = vertexProgram pipelineStateDescriptor.fragmentFunction = fragmentProgram pipelineStateDescriptor.colorAttachments[0].pixelFormat = .BGRA8Unorm pipelineStateDescriptor.colorAttachments[0].blendingEnabled = true pipelineStateDescriptor.sampleCount = 4 pipelineStateDescriptor.colorAttachments[0].rgbBlendOperation = MTLBlendOperation.Add pipelineStateDescriptor.colorAttachments[0].alphaBlendOperation = MTLBlendOperation.Add pipelineStateDescriptor.colorAttachments[0].sourceRGBBlendFactor = MTLBlendFactor.SourceAlpha pipelineStateDescriptor.colorAttachments[0].sourceAlphaBlendFactor = MTLBlendFactor.SourceAlpha pipelineStateDescriptor.colorAttachments[0].destinationRGBBlendFactor = MTLBlendFactor.OneMinusSourceAlpha pipelineStateDescriptor.colorAttachments[0].destinationAlphaBlendFactor = MTLBlendFactor.OneMinusSourceAlpha let desc = MTLTextureDescriptor() desc.textureType = MTLTextureType.Type2DMultisample desc.width = Int(self.view.frame.width) desc.height = Int(self.view.frame.height) desc.sampleCount = 4 desc.pixelFormat = .BGRA8Unorm self.sampletex = self.device.newTextureWithDescriptor(desc) // When rendering let renderPassDescriptor = MTLRenderPassDescriptor() renderPassDescriptor.colorAttachments[0].texture = sampletex renderPassDescriptor.colorAttachments[0].resolveTexture = drawable.texture renderPassDescriptor.colorAttachments[0].loadAction = .Clear renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColor(red: 23/255.0, green: 26/255.0, blue: 31/255.0, alpha: 0.0) renderPassDescriptor.colorAttachments[0].storeAction = .MultisampleResolve let commandBuffer = commandQueue.commandBuffer() let renderEncoder = commandBuffer.renderCommandEncoderWithDescriptor(renderPassDescriptor) renderEncoder.setRenderPipelineState(pipelineState) 

Answer 1

This is greatly simplified with MTKView (just set sampleCount to the desired number of MSAA samples in the view and pipeline descriptor), but here are the steps for your own.

• When creating the state of the rendering pipeline, set the sampleCount descriptor for the state of the rendering pipeline to your multisample account.

• At startup and when resizing the layer, create a multiprocessor texture with dimensions equal to the size of your layer, creating a texture descriptor whose textureType is MTLTextureType2DMultisample and whose sampleCount is your multisample. If you use a depth and / or stencil buffer, set these properties in your descriptors as well.

• When rendering, set the MSAA texture as the texture main attachment of the rendering visualization descriptor and set the current texture to be resolveTexture as resolveTexture .

• Set the storeAction color attachment to MTLStoreActionMultisampleResolve so that the MSAA texture is enabled in the renderbuffer at the end of the pass.

• Draw and imagine, as usual.