iOSデバイスのSwift 3にメタルを設定する

Question

私はAppleのMetalBasicTessellationプロジェクトをiPad Air 3ですばやく3で動作させようとしていましたが、これまで失敗しました。不本意ながら、このプロジェクトにはiOSの実装（objectiveCで書かれた、すばらしい遊び場）がありますが、迅速な実装はありません。

私はコンパイルするためのコードを得ますが、次のエラーで私のiPad上で動作するように失敗してきた

：

2017-05-14 14:25:54.268400-0700 MetalBasicTessellation[2436:570250] -[MTLRenderPipelineDescriptorInternal validateWithDevice:], line 1728: error 'tessellation is only supported on MTLFeatureSet_iOS_GPUFamily3_v1 and later' 

私はiPadのエア2に準拠していることをかなり確信しているが、私はエラーを感じています不適切に構成されたMetalKitViewが原因です。私は、プロジェクトの目的地と遊び場のファイルからできることをリバース・エンジニアリングしましたが、私が現在の専門知識で理解できる限りは行っています。

// 
// ViewController.swift 
// MetalBasicTessellation 
// 
// Created by vladimir sierra on 5/10/17. 
// 
// 

import UIKit 
import Metal 
import MetalKit 

class ViewController: UIViewController { 

    @IBOutlet weak var mtkView: MTKView! 

    // Seven steps required to set up metal for rendering: 

    // 1. Create a MTLDevice 
    // 2. Create a CAMetalLayer 
    // 3. Create a Vertex Buffer 

    // 4. Create a Vertex Shader 
    // 5. Create a Fragment Shader 

    // 6. Create a Render Pipeline 
    // 7. Create a Command Queue 

    var device: MTLDevice! // to be initialized in viewDidLoad 
    //var metalLayer: CAMetalLayer! // to be initialized in viewDidLoad 
    var vertexBuffer: MTLBuffer! // to be initialized in viewDidLoad 
    var library: MTLLibrary! 

    // once we create a vertex and fragment shader, we combine them in an object called render pipeline. In Metal the shaders are precompiled, and the render pipeline configuration is compiled after you first set it up. This makes everything extremely efficient 

    var renderPipeline: MTLRenderPipelineState! // to be initialized in viewDidLoad 
    var commandQueue: MTLCommandQueue! // to be initialized in viewDidLoad 

    //var timer: CADisplayLink! // function to be called every time the device screen refreshes so we can redraw the screen 



    override func viewDidLayoutSubviews() { 
    super.viewDidLayoutSubviews() 
    /* 
    if let window = view.window { 
     let scale = window.screen.nativeScale // (2 for iPhone 5s, 6 and iPads; 3 for iPhone 6 Plus) 
     let layerSize = view.bounds.size 
     // apply the scale to increase the drawable texture size. 
     view.contentScaleFactor = scale 
     //metalLayer.frame = CGRect(x: 0, y: 0, width: layerSize.width, height: layerSize.height) 
     //metalLayer.drawableSize = CGSize(width: layerSize.width * scale, height: layerSize.height * scale) 
    } */ 
    } 

    override func viewDidLoad() { 
    super.viewDidLoad() 

    device = MTLCreateSystemDefaultDevice() // returns a reference to the default MTLDevice 

    //device.supportsFeatureSet(MTLFeatureSet_iOS_GPUFamily3_v2) 



    // set up layer to display metal content 
    //metalLayer = CAMetalLayer()   // initialize metalLayer 
    //metalLayer.device = device   // device the layer should use 
    //metalLayer.pixelFormat = .bgra8Unorm // normalized 8 bit rgba 
    //metalLayer.framebufferOnly = true // set to true for performance issues 
    //view.layer.addSublayer(metalLayer) // add sublayer to main view's layer 

    // precompile custom metal functions 

    let defaultLibrary = device.newDefaultLibrary()! // MTLLibrary object with precompiled shaders 


    let fragmentProgram = defaultLibrary.makeFunction(name: "tessellation_fragment") 
    let vertexProgram = defaultLibrary.makeFunction(name: "tessellation_vertex_triangle") 

    // Setup Compute Pipeline 
    let kernelFunction = defaultLibrary.makeFunction(name: "tessellation_kernel_triangle") 
    var computePipeline: MTLComputePipelineState? 
    do { 
     computePipeline = try device.makeComputePipelineState(function: kernelFunction!) 
    } catch let error as NSError { 
     print("compute pipeline error: " + error.description) 
    } 

    // Setup Vertex Descriptor 
    let vertexDescriptor = MTLVertexDescriptor() 
    vertexDescriptor.attributes[0].format = .float4 
    vertexDescriptor.attributes[0].offset = 0 
    vertexDescriptor.attributes[0].bufferIndex = 0; 
    vertexDescriptor.layouts[0].stepFunction = .perPatchControlPoint 
    vertexDescriptor.layouts[0].stepRate = 1 
    vertexDescriptor.layouts[0].stride = 4*MemoryLayout<Float>.size 

    // Setup Render Pipeline 
    let renderPipelineDescriptor = MTLRenderPipelineDescriptor() 
    renderPipelineDescriptor.vertexDescriptor = vertexDescriptor 
    //renderPipelineDescriptor.fragmentFunction = defaultLibrary.makeFunction(name: "tessellation_fragment") 
    renderPipelineDescriptor.fragmentFunction = fragmentProgram 
    //renderPipelineDescriptor.vertexFunction = defaultLibrary.makeFunction(name: "tessellation_vertex_triangle") 
    renderPipelineDescriptor.vertexFunction = vertexProgram 

    //renderPipelineDescriptor.colorAttachments[0].pixelFormat = .bgra8Unorm // normalized 8 bit rgba 
    renderPipelineDescriptor.colorAttachments[0].pixelFormat = mtkView.colorPixelFormat 

    renderPipelineDescriptor.isTessellationFactorScaleEnabled = false 
    renderPipelineDescriptor.tessellationFactorFormat = .half 
    renderPipelineDescriptor.tessellationControlPointIndexType = .none 
    renderPipelineDescriptor.tessellationFactorStepFunction = .constant 
    renderPipelineDescriptor.tessellationOutputWindingOrder = .clockwise 
    renderPipelineDescriptor.tessellationPartitionMode = .fractionalEven 
    renderPipelineDescriptor.maxTessellationFactor = 64; 

    // Compile renderPipeline 
    do { 
     renderPipeline = try device.makeRenderPipelineState(descriptor: renderPipelineDescriptor) 
    } catch let error as NSError { 
     print("render pipeline error: " + error.description) 
    } 

    // Setup Buffers 
    let tessellationFactorsBuffer = device.makeBuffer(length: 256, options: MTLResourceOptions.storageModePrivate) 
    let controlPointPositions: [Float] = [ 
     -0.8, -0.8, 0.0, 1.0, // lower-left 
     0.0, 0.8, 0.0, 1.0, // upper-middle 
     0.8, -0.8, 0.0, 1.0, // lower-right 
    ] 
    let controlPointsBuffer = device.makeBuffer(bytes: controlPointPositions, length:256 , options: []) 

    // Tessellation Pass 
    let commandBuffer = commandQueue.makeCommandBuffer() 

    let computeCommandEncoder = commandBuffer.makeComputeCommandEncoder() 
    computeCommandEncoder.setComputePipelineState(computePipeline!) 

    let edgeFactor: [Float] = [16.0] 
    let insideFactor: [Float] = [8.0] 
    computeCommandEncoder.setBytes(edgeFactor, length: MemoryLayout<Float>.size, at: 0) 
    computeCommandEncoder.setBytes(insideFactor, length: MemoryLayout<Float>.size, at: 1) 
    computeCommandEncoder.setBuffer(tessellationFactorsBuffer, offset: 0, at: 2) 
    computeCommandEncoder.dispatchThreadgroups(MTLSizeMake(1, 1, 1), threadsPerThreadgroup: MTLSizeMake(1, 1, 1)) 
    computeCommandEncoder.endEncoding() 

    let renderPassDescriptor = mtkView.currentRenderPassDescriptor 
    let renderCommandEncoder = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptor!) 
    renderCommandEncoder.setRenderPipelineState(renderPipeline!) 
    renderCommandEncoder.setVertexBuffer(controlPointsBuffer, offset: 0, at: 0) 
    renderCommandEncoder.setTriangleFillMode(.lines) 
    renderCommandEncoder.setTessellationFactorBuffer(tessellationFactorsBuffer, offset: 0, instanceStride: 0) 
    renderCommandEncoder.drawPatches(numberOfPatchControlPoints: 3, patchStart: 0, patchCount: 1, patchIndexBuffer: nil, patchIndexBufferOffset: 0, instanceCount: 1, baseInstance: 0) 
    renderCommandEncoder.endEncoding() 

    commandBuffer.present(mtkView.currentDrawable!) 
    commandBuffer.commit() 
    commandBuffer.waitUntilCompleted() 
    /* 
    // finally create an ordered list of commands forthe GPU to execute 
    commandQueue = device.makeCommandQueue() 

    timer = CADisplayLink(target: self, selector: #selector(ViewController.gameloop)) // call gameloop every time the screen refreshes 
    timer.add(to: RunLoop.main, forMode: RunLoopMode.defaultRunLoopMode) 

    */ 



    } 

    override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
    } 

    /* 
    func render() { 
    guard let drawable = metalLayer?.nextDrawable() else { return } // returns the texture to draw into in order for something to appear on the screen 
    //objectToDraw.render(commandQueue: commandQueue, renderPipeline: renderPipeline, drawable: drawable, clearColor: nil) 
    } 

    // this is the routine that gets run every time the screen refreshes 
    func gameloop() { 
    autoreleasepool { 
     self.render() 
    } 
    } */ 


} 

全体のgitはいくつかの種類の金属の第一人者-魂が手を貸すだろうhere

を見つけることができますか？そこからの文書は非常にまばらです。

Answer 1

docs for MTLFeatureSet_iOS_GPUFamily3_v1は言う：

Introduced with the Apple A9 GPU and iOS 9.0.

（強調は追加。）

一方、iOS Device Compatibility Reference: Hardware GPU Information記事は、iPadのエア2はA8 GPUを持っていると言います。

私はあなたのデバイスが可能であるとは思わない。

通常、MTKViewの設定はサポートされている機能セットには影響しません。それはデバイスに固有のことです（ハードウェアとOSのバージョンの組み合わせ）。 supportsFeatureSet(_:) method of MTLDeviceを使用して、デバイスが特定の機能セットをサポートしているかどうかを照会することができます。デバイスは、MTKViewのような他のオブジェクトから独立して取得することができ（通常は）、そのような他のオブジェクトに依存することはできません。