MetalKit - Drawable.texture断言错误

Question

我是MetalKit的新手，并试图将本教程从playground转换回OSX应用程序：

    import MetalKit

public class MetalView: MTKView {

    var queue: MTLCommandQueue! = nil
    var cps: MTLComputePipelineState! = nil

    required public init(coder: NSCoder) {
        super.init(coder: coder)
        device = MTLCreateSystemDefaultDevice()
        registerShaders()
    }


    override public func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)
        if let drawable = currentDrawable {
            let command_buffer = queue.commandBuffer()
            let command_encoder = command_buffer.computeCommandEncoder()
            command_encoder.setComputePipelineState(cps)
            command_encoder.setTexture(drawable.texture, atIndex: 0)
            let threadGroupCount = MTLSizeMake(8, 8, 1)
            let threadGroups = MTLSizeMake(drawable.texture.width / threadGroupCount.width, drawable.texture.height / threadGroupCount.height, 1)
            command_encoder.dispatchThreadgroups(threadGroups, threadsPerThreadgroup: threadGroupCount)
            command_encoder.endEncoding()
            command_buffer.presentDrawable(drawable)
            command_buffer.commit()
        }
    }

    func registerShaders() {
        queue = device!.newCommandQueue()
        do {
            let library = device!.newDefaultLibrary()!
            let kernel = library.newFunctionWithName("compute")!
            cps = try device!.newComputePipelineStateWithFunction(kernel)
        } catch let e {
            Swift.print("\(e)")
        }
    }
}

我在线路上有个错误：

command_encoder.setTexture(drawable.texture, atIndex: 0)

失败的断言“`frameBufferOnly纹理不支持计算”。

我怎么解决这个问题？

Answer 1

如果您想从计算函数中写入绘图的纹理，则需要告诉MTKView，它应该将其层配置为不只是帧缓冲区：

metalView.framebufferOnly = false

如果将此值设置为false，您的可绘制将为您提供带有shaderWrite用法标志集的纹理，这是从着色器函数编写纹理时所必需的。

Answer 2

即使我将frameBufferOnly设置为false，并在使用可绘制之前打印布尔值以进行双重检查，我也有相同的问题。

但是，当我关闭GPU frame capture时，就不会再有断言了(至少现在是这样)。还是不知道为什么。

Menu > Scheme > Edit Scheme > Run > Options > GPU Frame Capture：禁用