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如何将MetalKit纹理加载器与Metal堆一起使用?

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我有一组金属纹理作为纹理集存储在Xcode Assets目录中 . 我正在使用 MTKTextureLoader.newTexture(name:scaleFactor:bundle:options) 加载这些 .

然后我使用 MTLArgumentEncoder 将所有纹理编码为Metal 2参数缓冲区 .

这很好用 . 然而,2017年WWDC金融时报 Session recommends combining argument buffers with resource heaps for even better performance,我非常渴望尝试这一点 . 根据Argument Buffer documentation,不必在参数缓冲区中的每个纹理上调用 MTLRenderCommandEncoder.useResource ,而只需在分配纹理的堆上调用 useHeap .

但是,我还没有找到一种直接使用 MTKTextureLoaderMTLHeap 的方法 . 它似乎没有一个加载选项来从堆中分配纹理 .

我猜这个方法是:

  • MTKTextureLoader 加载纹理

  • 为每个纹理反向设计一组 MTLTextureDescriptor 对象

  • 使用纹理描述符来创建适当大小的 MTLHeap

  • MTLHeap 分配一组新纹理

  • 使用一些方法来复制纹理,也许 replaceBytes 甚至可能是 MTLBlitCommandEncoder

  • 释放用 MTKTextureLoader 加载的原始纹理

这似乎是一个相当冗长的方法,我没有看到任何这样的例子,所以我想我先问这里,以防我错过了一些明显的东西 .

我应该放弃 MTKTextureLoader ,并在从资产目录中加载纹理时搜索一些前MetalKit艺术品吗?

我正在使用Swift,但很高兴接受Objective-C的答案 .

1 回答

  • 0

    好吧,我上面概述的方法似乎有效 . 正如预测的那样,它非常啰嗦 . 我很想知道是否有人有更优雅的东西 .

    enum MetalError: Error {
        case anErrorOccured
    }
    
    extension MTLTexture {
        var descriptor: MTLTextureDescriptor {
            let descriptor = MTLTextureDescriptor()
            descriptor.width = width
            descriptor.height = height
            descriptor.depth = depth
            descriptor.textureType = textureType
            descriptor.cpuCacheMode = cpuCacheMode
            descriptor.storageMode = storageMode
            descriptor.pixelFormat = pixelFormat
            descriptor.arrayLength = arrayLength
            descriptor.mipmapLevelCount = mipmapLevelCount
            descriptor.sampleCount = sampleCount
            descriptor.usage = usage
            return descriptor
        }
    
        var size: MTLSize {
            return MTLSize(width: width, height: height, depth: depth)
        }
    }
    
    extension MTKTextureLoader {
        func newHeap(withTexturesNamed names: [String], queue: MTLCommandQueue, scaleFactor: CGFloat, bundle: Bundle?, options: [MTKTextureLoader.Option : Any]?, onCompletion: (([MTLTexture]) -> Void)?) throws -> MTLHeap {
            let device = queue.device
            let sourceTextures = try names.map { name in
                return try newTexture(name: name, scaleFactor: scaleFactor, bundle: bundle, options: options)
            }
            let storageMode: MTLStorageMode = .private
            let descriptors: [MTLTextureDescriptor] = sourceTextures.map { source in
                let desc = source.descriptor
                desc.storageMode = storageMode
                return desc
            }
            let sizeAligns = descriptors.map { device.heapTextureSizeAndAlign(descriptor: $0) }
            let heapDescriptor = MTLHeapDescriptor()
            heapDescriptor.size = sizeAligns.reduce(0) { $0 + $1.size }
            heapDescriptor.cpuCacheMode = descriptors[0].cpuCacheMode
            heapDescriptor.storageMode = storageMode
            guard let heap = device.makeHeap(descriptor: heapDescriptor),
                let buffer = queue.makeCommandBuffer(),
                let blit = buffer.makeBlitCommandEncoder()
                else {
                throw MetalError.anErrorOccured
            }
            let destTextures = descriptors.map { descriptor in
                return heap.makeTexture(descriptor: descriptor)
            }
            let origin = MTLOrigin()
            zip(sourceTextures, destTextures).forEach {(source, dest) in
                blit.copy(from: source, sourceSlice: 0, sourceLevel: 0, sourceOrigin: origin, sourceSize: source.size, to: dest, destinationSlice: 0, destinationLevel: 0, destinationOrigin: origin)
                blit.generateMipmaps(for: dest)
            }
            blit.endEncoding()
            buffer.addCompletedHandler { _ in
                onCompletion?(destTextures)
            }
            buffer.commit()
            return heap
        }
    }
    

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