问如何将16位图像加载到金属纹理中？

EN

func convertRGBF32ToRGBAF16(_ src: UnsafePointer<Float>, _ dst: UnsafeMutablePointer<UInt16>, pixelCount: Int) {
    for i in 0..<pixelCount {
        storeAsF16(src[i * 3 + 0], dst + (i * 4) + 0)
        storeAsF16(src[i * 3 + 1], dst + (i * 4) + 1)
        storeAsF16(src[i * 3 + 2], dst + (i * 4) + 2)
        storeAsF16(1.0, dst + (i * 4) + 3)
    }
}

func loadEXRTexture(_ url: URL, device: MTLDevice) -> MTLTexture? {
    guard let imageSource = CGImageSourceCreateWithURL(url as CFURL, nil) else { return nil }

    let options = [ kCGImageSourceShouldCache : true, kCGImageSourceShouldAllowFloat : true ] as CFDictionary
    guard let image = CGImageSourceCreateImageAtIndex(imageSource, 0, options) else { return nil }

    let descriptor = MTLTextureDescriptor.texture2DDescriptor(pixelFormat: .rgba16Float,
                                                              width: image.width,
                                                              height: image.height,
                                                              mipmapped: false)
    descriptor.usage = .shaderRead
    guard let texture = device.makeTexture(descriptor: descriptor) else { return nil }

    if image.bitsPerComponent == 32 && image.bitsPerPixel == 96 {
        let srcData: CFData! = image.dataProvider?.data
        CFDataGetBytePtr(srcData).withMemoryRebound(to: Float.self, capacity: image.width * image.height * 3) { srcPixels in
            let dstPixels = UnsafeMutablePointer<UInt16>.allocate(capacity: 4 * image.width * image.height)
            convertRGBF32ToRGBAF16(srcPixels, dstPixels, pixelCount: image.width * image.height)
            texture.replace(region: MTLRegionMake2D(0, 0, image.width, image.height),
                            mipmapLevel: 0,
                            withBytes: dstPixels,
                            bytesPerRow: MemoryLayout<UInt16>.size * 4 * image.width)
            dstPixels.deallocate()
        }
    }

    return texture
}

#include <stdint.h>
static inline void storeAsF16(float value, uint16_t *pointer) { *(__fp16 *)pointer = value; }