问不能用采样器显示纹理
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Stack Overflow用户

提问于 2016-01-25 00:39:29

回答 1查看 462关注 0票数 1

我试图显示一个加载了MTKTextureLoader的纹理，我有一个缓冲区来存储我的顶点坐标(我构建了两个三角形来在其中有一个矩形来显示我的图像)，然后我有一个缓冲区来存储每个顶点的纹理坐标。

我做了一个取样器从我的纹理中采样数据，问题是我什么也没有得到(黑色图像)。

我提供了Swift代码，以防我的错误来自那里，但我认为它来自金属代码。如果您查看我的片段着色器，您将看到两个注释，它们显示了一些我无法理解的东西:

如果我将坐标直接交给样本函数，它就会工作(用与给定坐标对应的颜色来表示三角形)。
如果我把传递给采样器的坐标作为颜色分量，它也会显示一些相干的东西(三角形在给定坐标的函数中着色)。

所以它似乎不是来自采样器，也不是来自坐标，这是我不明白的。

这是我的Swift代码：

import Cocoa
import MetalKit
import Metal

class ViewController: NSViewController, MTKViewDelegate {

    var device:MTLDevice!
    var texture:MTLTexture!
    var commandQueue:MTLCommandQueue!
    var vertexBuffer:MTLBuffer!
    var vertexCoordinates:[Float] = [
        -1, 1, 0, 1,
        -1, -1, 0, 1,
        1, -1, 0,  1,

        1,-1,0,1,
        1,1,0,1,
        -1,1,0,1,

    ]

    var vertexUVBuffer:MTLBuffer!
    var vertexUVCoordinates:[Float] = [
    0,1,
    0,0,
    1,0,
    1,0,
    1,1,
    0,1
    ]

    var library:MTLLibrary!
    var defaultPipelineState:MTLRenderPipelineState!
    var samplerState:MTLSamplerState!

    @IBOutlet var metalView: MTKView!

    override func viewDidLoad() {
        super.viewDidLoad()

        device = MTLCreateSystemDefaultDevice()
        let textureLoader = MTKTextureLoader(device: device)

        metalView.device = device
        metalView.delegate = self
        metalView.preferredFramesPerSecond = 0
        metalView.sampleCount = 4



        texture = try! textureLoader.newTextureWithContentsOfURL(NSBundle.mainBundle().URLForResource("abeilles", withExtension: "jpg")!, options: [MTKTextureLoaderOptionAllocateMipmaps:NSNumber(bool: true)])

        commandQueue = device.newCommandQueue()
        library = device.newDefaultLibrary()


        vertexBuffer = device.newBufferWithBytes(&vertexCoordinates, length: sizeof(Float)*vertexCoordinates.count, options: [])
        vertexUVBuffer = device.newBufferWithBytes(&vertexUVCoordinates, length: sizeof(Float)*vertexUVCoordinates.count, options: [])



        let renderPipelineDescriptor = MTLRenderPipelineDescriptor()
        renderPipelineDescriptor.vertexFunction = library.newFunctionWithName("passTroughVertex")
        renderPipelineDescriptor.fragmentFunction = library.newFunctionWithName("myFragmentShader")
        renderPipelineDescriptor.sampleCount = metalView.sampleCount
        renderPipelineDescriptor.colorAttachments[0].pixelFormat = metalView.colorPixelFormat
        defaultPipelineState = try! device.newRenderPipelineStateWithDescriptor(renderPipelineDescriptor)
        let samplerDescriptor = MTLSamplerDescriptor()
        samplerDescriptor.minFilter = .Linear
        samplerDescriptor.magFilter = .Linear
        samplerDescriptor.mipFilter = .Linear
        samplerDescriptor.sAddressMode = .ClampToEdge
        samplerDescriptor.rAddressMode = .ClampToEdge
        samplerDescriptor.tAddressMode = .ClampToEdge
        samplerDescriptor.normalizedCoordinates = true

        samplerState = device.newSamplerStateWithDescriptor(samplerDescriptor)
        metalView.draw()






        // Do any additional setup after loading the view.
    }

    func drawInMTKView(view: MTKView) {

        let commandBuffer = commandQueue.commandBuffer()
        let commandEncoder = commandBuffer.renderCommandEncoderWithDescriptor(metalView.currentRenderPassDescriptor!)
        commandEncoder.setRenderPipelineState(defaultPipelineState)

        commandEncoder.setVertexBuffer(vertexBuffer, offset: 0, atIndex: 0)
        commandEncoder.setVertexBuffer(vertexUVBuffer, offset:0, atIndex:1)
        commandEncoder.setFragmentSamplerState(samplerState, atIndex: 0)
        commandEncoder.setFragmentTexture(texture, atIndex: 0)
        commandEncoder.drawPrimitives(MTLPrimitiveType.Triangle, vertexStart: 0, vertexCount: 6, instanceCount: 1)

        commandEncoder.endEncoding()
        commandBuffer.presentDrawable(metalView.currentDrawable!)
        commandBuffer.commit()

    }

    func mtkView(view: MTKView, drawableSizeWillChange size: CGSize) {
        // view.draw()
    }

    override var representedObject: AnyObject? {
        didSet {
        // Update the view, if already loaded.
        }
    }


}

这是我的金属代码：

#include <metal_stdlib>
using namespace metal;


struct VertexOut {
    float4 position [[position]];
    float2 texCoord;
};


vertex VertexOut passTroughVertex(uint vid [[ vertex_id]],
                                  constant float4 *vertexPosition [[ buffer(0) ]],
                                  constant float2 *vertexUVPos [[ buffer(1)]]) {

    VertexOut vertexOut;
    vertexOut.position = vertexPosition[vid];
    vertexOut.texCoord = vertexUVPos[vid];
    return vertexOut;
}

fragment float4 myFragmentShader(VertexOut inFrag [[stage_in]],
                                 texture2d<float> myTexture [[ texture(0)]],
                                 sampler mySampler [[ sampler(0) ]]) {


    float4 myColor = myTexture.sample(mySampler,inFrag.texCoord);
    // myColor = myTexture.sample(mySampler,float2(1));
    // myColor = float4(inFrag.texCoord.r,inFrag.texCoord.g,0,1);

    return myColor;
}