swift - MTKView 始终将背景颜色渲染为红色

Question

我想在 Mac 应用程序上使用 MTKView。初始化 MTKView 后，它显示红色而不是预期的清晰颜色我的笔记本电脑是 macOS Catalina 10.15.2 的 MacBook Pro，它在 macOS Mojave 10.14.6 的 iMac 上呈现黑色背景

我尝试将 metalView 的 pixelFormat (MTLPixelFormat.bgra8Unorm) 交换为 MTLPixelFormat.rgba16Float 或其他。背景颜色也不正确。

MTLTexture 创建函数是 MTLTextureDescriptor.texture2DDescriptor(pixelFormat:metalView.colorPixelFormat, width: Int(metalView.frame.size.width), height: Int(metalView.frame.size .height), mipmapped: false)

可能是.metal文件有问题，但我没看懂

我已将项目发布到 Github。 here

import Cocoa
import MetalKit
import simd

struct Vertex {
    var position: vector_float4
    var textCoord: vector_float2

    init(position: CGPoint, textCoord: CGPoint) {
        self.position = [Float(position.x), Float(position.y), 0 ,1]
        self.textCoord = [Float(textCoord.x), Float(textCoord.y)]
    }
}

class Matrix {

    private(set) var m: [Float]

    static var identity = Matrix()

    private init() {
        m = [1, 0, 0, 0,
             0, 1, 0, 0,
             0, 0, 1, 0,
             0, 0, 0, 1
        ]
    }

    @discardableResult
    func translation(x: Float, y: Float, z: Float) -> Matrix {
        m[12] = x
        m[13] = y
        m[14] = z
        return self
    }

    @discardableResult
    func scaling(x: Float, y: Float, z: Float)  -> Matrix  {
        m[0] = x
        m[5] = y
        m[10] = z
        return self
    }
}

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate, MTKViewDelegate {

    @IBOutlet weak var window: NSWindow!

    @IBOutlet weak var metalView: MTKView!

    private var commandQueue: MTLCommandQueue?

    private var pipelineState: MTLRenderPipelineState!
    private var render_target_vertex: MTLBuffer!
    private var render_target_uniform: MTLBuffer!

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        // Insert code here to initialize your application

        metalView.device = MTLCreateSystemDefaultDevice()
        metalView.delegate = self

        commandQueue = metalView.device?.makeCommandQueue()

        setupTargetUniforms()

        do {
            try setupPiplineState()
        } catch {
            fatalError("Metal initialize failed: \(error.localizedDescription)")
        }
    }

    private func setupTargetUniforms() {
        let size = metalView.frame.size
        let w = size.width, h = size.height
        let vertices = [
            Vertex(position: CGPoint(x: 0 , y: 0), textCoord: CGPoint(x: 0, y: 0)),
            Vertex(position: CGPoint(x: w , y: 0), textCoord: CGPoint(x: 1, y: 0)),
            Vertex(position: CGPoint(x: 0 , y: h), textCoord: CGPoint(x: 0, y: 1)),
            Vertex(position: CGPoint(x: w , y: h), textCoord: CGPoint(x: 1, y: 1)),
        ]
        render_target_vertex = metalView.device?.makeBuffer(bytes: vertices, length: MemoryLayout<Vertex>.stride * vertices.count, options: .cpuCacheModeWriteCombined)

        let metrix = Matrix.identity
        metrix.scaling(x: 2 / Float(size.width), y: -2 / Float(size.height), z: 1)
        metrix.translation(x: -1, y: 1, z: 0)
        render_target_uniform = metalView.device?.makeBuffer(bytes: metrix.m, length: MemoryLayout<Float>.size * 16, options: [])
    }

    private func setupPiplineState() throws {

        let library = try metalView.device?.makeDefaultLibrary(bundle: Bundle.main)
        let vertex_func = library?.makeFunction(name: "vertex_render_target")
        let fragment_func = library?.makeFunction(name: "fragment_render_target")
        let rpd = MTLRenderPipelineDescriptor()
        rpd.vertexFunction = vertex_func
        rpd.fragmentFunction = fragment_func
        rpd.colorAttachments[0].pixelFormat = metalView.colorPixelFormat
        //        rpd.colorAttachments[0].isBlendingEnabled = true
        //        rpd.colorAttachments[0].alphaBlendOperation = .add
        //        rpd.colorAttachments[0].rgbBlendOperation = .add
        //        rpd.colorAttachments[0].sourceRGBBlendFactor = .sourceAlpha
        //        rpd.colorAttachments[0].sourceAlphaBlendFactor = .one
        //        rpd.colorAttachments[0].destinationRGBBlendFactor = .oneMinusSourceAlpha
        //        rpd.colorAttachments[0].destinationAlphaBlendFactor = .oneMinusSourceAlpha
        pipelineState = try metalView.device?.makeRenderPipelineState(descriptor: rpd)
    }

    func applicationWillTerminate(_ aNotification: Notification) {
        // Insert code here to tear down your application
    }

    func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {


    }

    func draw(in view: MTKView) {
        let renderPassDescriptor = MTLRenderPassDescriptor()
        let attachment = renderPassDescriptor.colorAttachments[0]
        attachment?.clearColor = metalView.clearColor
        attachment?.texture = metalView.currentDrawable?.texture
        attachment?.loadAction = .clear
        attachment?.storeAction = .store

        let commandBuffer = commandQueue?.makeCommandBuffer()

        let commandEncoder = commandBuffer?.makeRenderCommandEncoder(descriptor: renderPassDescriptor)

        commandEncoder?.setRenderPipelineState(pipelineState)

        commandEncoder?.setVertexBuffer(render_target_vertex, offset: 0, index: 0)
        commandEncoder?.setVertexBuffer(render_target_uniform, offset: 0, index: 1)

        let textureDescriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: metalView.colorPixelFormat,
                                                                         width: Int(metalView.frame.size.width),
                                                                         height: Int(metalView.frame.size.height),
                                                                         mipmapped: false)
        textureDescriptor.usage = [.renderTarget, .shaderRead]
        let texture = metalView.device?.makeTexture(descriptor: textureDescriptor)
        commandEncoder?.setFragmentTexture(texture, index: 0)
        commandEncoder?.drawPrimitives(type: .triangleStrip, vertexStart: 0, vertexCount: 4)

        commandEncoder?.endEncoding()
        if let drawable = metalView.currentDrawable {
            commandBuffer?.present(drawable)
        }
        commandBuffer?.commit()
    }
}

谁能帮我找出问题所在？

Answer 1

您正在从未初始化的纹理中采样。

在您的 MetalView 的 draw 方法中，您从从未渲染过的 screenTarget 变量绑定(bind)纹理。

创建 Metal 纹理时，其内容是未定义的。它们可能是红色、黑色、随机噪声或其他任何东西。