3d texture sampler problem

Question

Created May ’21

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I am using a color lookup table to create a 3d texture, and use input color to find output color. but I found output color has some interrupt layer. Is this sampler sample 3d texture by using trilinear?

This is my code for creating 3d texture
the lutData is a array of r, g, b, a, r, g, b, a, ....
lutSize is the lookup table size, it's 32 or 64.

Code Block func create3DTextureFromLutData(lutData: [Float], lutSize: Int) -> MTLTexture? {
    let desc = MTLTextureDescriptor()
    desc.textureType = .type3D
    desc.pixelFormat = .rgba32Float
    desc.width = lutSize
    desc.height = lutSize
    desc.depth = lutSize
    desc.usage = .shaderRead
     
    guard let texture = _device.makeTexture(descriptor: desc) else { return nil}
     
    texture.replace(region: MTLRegion(origin: .init(x: 0, y: 0, z: 0), size: .init(width: lutSize, height: lutSize, depth: lutSize)), mipmapLevel: 0, slice: 0, withBytes: lutData, bytesPerRow: lutSize * MemoryLayout<Float>.size * 4, bytesPerImage: lutSize * lutSize * MemoryLayout<Float>.size * 4)
     
    return texture
  }

and in my shader, I just want to sample it like this.

Code Block metalconstexpr sampler textureSampler = sampler(mag_filter::linear, min_filter::linear, mip_filter::linear, address::clamp_to_edge);
half4 lutWith3dTexture(half4 inputColor, short lutSize, half lutStrength, texture3d<float, access::sample> lut3dTexture, sampler textureSampler) {
  half4 originColor = inputColor;
  float3 coor = float3(((inputColor.rgb * (lutSize - 1)) + 0.5) / lutSize);
  half4 resultColor = half4(lut3dTexture.sample(textureSampler, coor));
   
  return mix(originColor, resultColor, lutStrength);
}

I am trying different filter::xxxx didn't help anything.

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Answer 1

PhonJac OP

May ’21

You can check out the result image

Code Block good result: https://i.imgur.com/PwAH49E.png
bad result: https://i.imgur.com/M75KUWv.png

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