Strange output on Array3D(3) toArray()

What is wrong?

When using a kernel to draw a CPU Array3D(3) into a texture and then converted back using toArray(), the resulting array is very strange and wrong, with some values being correct and others being either duplicated or entirely incorrect.

Where does it happen?

In GPU.js, running on my Windows 7 PC, headlessgl in node.js v12.18.1.

How do we replicate the issue?

Create a 3D array and assign each value set to its index in the array...
e.g.,

const gridSize = 8;
const buffer = [];
for (let x = 0; x < gridSize; x++) {
  let currXArr = [];
  buffer.push(currXArr);
  for (let y = 0; y < gridSize; y++) {
    let currYArr = [];
    currXArr.push(currYArr);
    for (let z = 0; z < gridSize; z++) {
      currYArr.push(new Float32Array([x,y,z]));
    }
  }
}

Build the following kernel:

const pipelineFuncSettings = {
  output: [gridSize, gridSize, gridSize],
  pipeline: true,
  returnType: 'Array(3)',
};
const copyFramebufferFuncImmutable = gpu.createKernel(function(framebufTex) {
  const voxelColour = framebufTex[this.thread.x][this.thread.y][this.thread.z];
  return [voxelColour[0], voxelColour[1], voxelColour[2]];
}, {...pipelineFuncSettings, immutable: true, argumentTypes: {framebufTex: 'Array3D(3)'}});

Draw the CPU buffer into a GPU texture and retrieve it as an array:

const bufferTex = copyFramebufferFuncImmutable(buffer);
const texArray  = bufferTex.toArray();

Then look to see if what we did was properly copied from the CPU -> GPU -> CPU:

function debugPrint(arr) {
  for (let x = 0; x < gridSize; x++) {
    for (let y = 0; y < gridSize; y++) {
      const temp = [];
      for (let z = 0; z < gridSize; z++) {
        const currColour = arr[x][y][z];
        temp.push("("+currColour[0].toFixed(0)+","+currColour[1].toFixed(0)+","+currColour[2].toFixed(0)+")")
      }
      strArr.push(temp.join(", "));
    }
  }
  console.log(strArr.join("\n"));
}

... and get this comparative abomination:

CPU (Original/Control) i.e., debugPrint(buffer);:

(0,0,0), (0,0,1), (0,0,2), (0,0,3), (0,0,4), (0,0,5), (0,0,6), (0,0,7)
(0,1,0), (0,1,1), (0,1,2), (0,1,3), (0,1,4), (0,1,5), (0,1,6), (0,1,7)
(0,2,0), (0,2,1), (0,2,2), (0,2,3), (0,2,4), (0,2,5), (0,2,6), (0,2,7)
(0,3,0), (0,3,1), (0,3,2), (0,3,3), (0,3,4), (0,3,5), (0,3,6), (0,3,7)
(0,4,0), (0,4,1), (0,4,2), (0,4,3), (0,4,4), (0,4,5), (0,4,6), (0,4,7)
(0,5,0), (0,5,1), (0,5,2), (0,5,3), (0,5,4), (0,5,5), (0,5,6), (0,5,7)
(0,6,0), (0,6,1), (0,6,2), (0,6,3), (0,6,4), (0,6,5), (0,6,6), (0,6,7)
(0,7,0), (0,7,1), (0,7,2), (0,7,3), (0,7,4), (0,7,5), (0,7,6), (0,7,7)
(1,0,0), (1,0,1), (1,0,2), (1,0,3), (1,0,4), (1,0,5), (1,0,6), (1,0,7)
(1,1,0), (1,1,1), (1,1,2), (1,1,3), (1,1,4), (1,1,5), (1,1,6), (1,1,7)
(1,2,0), (1,2,1), (1,2,2), (1,2,3), (1,2,4), (1,2,5), (1,2,6), (1,2,7)
(1,3,0), (1,3,1), (1,3,2), (1,3,3), (1,3,4), (1,3,5), (1,3,6), (1,3,7)
(1,4,0), (1,4,1), (1,4,2), (1,4,3), (1,4,4), (1,4,5), (1,4,6), (1,4,7)
(1,5,0), (1,5,1), (1,5,2), (1,5,3), (1,5,4), (1,5,5), (1,5,6), (1,5,7)
(1,6,0), (1,6,1), (1,6,2), (1,6,3), (1,6,4), (1,6,5), (1,6,6), (1,6,7)
(1,7,0), (1,7,1), (1,7,2), (1,7,3), (1,7,4), (1,7,5), (1,7,6), (1,7,7)
(2,0,0), (2,0,1), (2,0,2), (2,0,3), (2,0,4), (2,0,5), (2,0,6), (2,0,7)
(2,1,0), (2,1,1), (2,1,2), (2,1,3), (2,1,4), (2,1,5), (2,1,6), (2,1,7)
(2,2,0), (2,2,1), (2,2,2), (2,2,3), (2,2,4), (2,2,5), (2,2,6), (2,2,7)
(2,3,0), (2,3,1), (2,3,2), (2,3,3), (2,3,4), (2,3,5), (2,3,6), (2,3,7)
(2,4,0), (2,4,1), (2,4,2), (2,4,3), (2,4,4), (2,4,5), (2,4,6), (2,4,7)
(2,5,0), (2,5,1), (2,5,2), (2,5,3), (2,5,4), (2,5,5), (2,5,6), (2,5,7)
(2,6,0), (2,6,1), (2,6,2), (2,6,3), (2,6,4), (2,6,5), (2,6,6), (2,6,7)
(2,7,0), (2,7,1), (2,7,2), (2,7,3), (2,7,4), (2,7,5), (2,7,6), (2,7,7)
(3,0,0), (3,0,1), (3,0,2), (3,0,3), (3,0,4), (3,0,5), (3,0,6), (3,0,7)
(3,1,0), (3,1,1), (3,1,2), (3,1,3), (3,1,4), (3,1,5), (3,1,6), (3,1,7)
(3,2,0), (3,2,1), (3,2,2), (3,2,3), (3,2,4), (3,2,5), (3,2,6), (3,2,7)
(3,3,0), (3,3,1), (3,3,2), (3,3,3), (3,3,4), (3,3,5), (3,3,6), (3,3,7)
(3,4,0), (3,4,1), (3,4,2), (3,4,3), (3,4,4), (3,4,5), (3,4,6), (3,4,7)
(3,5,0), (3,5,1), (3,5,2), (3,5,3), (3,5,4), (3,5,5), (3,5,6), (3,5,7)
(3,6,0), (3,6,1), (3,6,2), (3,6,3), (3,6,4), (3,6,5), (3,6,6), (3,6,7)
(3,7,0), (3,7,1), (3,7,2), (3,7,3), (3,7,4), (3,7,5), (3,7,6), (3,7,7)
(4,0,0), (4,0,1), (4,0,2), (4,0,3), (4,0,4), (4,0,5), (4,0,6), (4,0,7)
(4,1,0), (4,1,1), (4,1,2), (4,1,3), (4,1,4), (4,1,5), (4,1,6), (4,1,7)
(4,2,0), (4,2,1), (4,2,2), (4,2,3), (4,2,4), (4,2,5), (4,2,6), (4,2,7)
(4,3,0), (4,3,1), (4,3,2), (4,3,3), (4,3,4), (4,3,5), (4,3,6), (4,3,7)
(4,4,0), (4,4,1), (4,4,2), (4,4,3), (4,4,4), (4,4,5), (4,4,6), (4,4,7)
(4,5,0), (4,5,1), (4,5,2), (4,5,3), (4,5,4), (4,5,5), (4,5,6), (4,5,7)
(4,6,0), (4,6,1), (4,6,2), (4,6,3), (4,6,4), (4,6,5), (4,6,6), (4,6,7)
(4,7,0), (4,7,1), (4,7,2), (4,7,3), (4,7,4), (4,7,5), (4,7,6), (4,7,7)
(5,0,0), (5,0,1), (5,0,2), (5,0,3), (5,0,4), (5,0,5), (5,0,6), (5,0,7)
(5,1,0), (5,1,1), (5,1,2), (5,1,3), (5,1,4), (5,1,5), (5,1,6), (5,1,7)
(5,2,0), (5,2,1), (5,2,2), (5,2,3), (5,2,4), (5,2,5), (5,2,6), (5,2,7)
(5,3,0), (5,3,1), (5,3,2), (5,3,3), (5,3,4), (5,3,5), (5,3,6), (5,3,7)
(5,4,0), (5,4,1), (5,4,2), (5,4,3), (5,4,4), (5,4,5), (5,4,6), (5,4,7)
(5,5,0), (5,5,1), (5,5,2), (5,5,3), (5,5,4), (5,5,5), (5,5,6), (5,5,7)
(5,6,0), (5,6,1), (5,6,2), (5,6,3), (5,6,4), (5,6,5), (5,6,6), (5,6,7)
(5,7,0), (5,7,1), (5,7,2), (5,7,3), (5,7,4), (5,7,5), (5,7,6), (5,7,7)
(6,0,0), (6,0,1), (6,0,2), (6,0,3), (6,0,4), (6,0,5), (6,0,6), (6,0,7)
(6,1,0), (6,1,1), (6,1,2), (6,1,3), (6,1,4), (6,1,5), (6,1,6), (6,1,7)
(6,2,0), (6,2,1), (6,2,2), (6,2,3), (6,2,4), (6,2,5), (6,2,6), (6,2,7)
(6,3,0), (6,3,1), (6,3,2), (6,3,3), (6,3,4), (6,3,5), (6,3,6), (6,3,7)
(6,4,0), (6,4,1), (6,4,2), (6,4,3), (6,4,4), (6,4,5), (6,4,6), (6,4,7)
(6,5,0), (6,5,1), (6,5,2), (6,5,3), (6,5,4), (6,5,5), (6,5,6), (6,5,7)
(6,6,0), (6,6,1), (6,6,2), (6,6,3), (6,6,4), (6,6,5), (6,6,6), (6,6,7)
(6,7,0), (6,7,1), (6,7,2), (6,7,3), (6,7,4), (6,7,5), (6,7,6), (6,7,7)
(7,0,0), (7,0,1), (7,0,2), (7,0,3), (7,0,4), (7,0,5), (7,0,6), (7,0,7)
(7,1,0), (7,1,1), (7,1,2), (7,1,3), (7,1,4), (7,1,5), (7,1,6), (7,1,7)
(7,2,0), (7,2,1), (7,2,2), (7,2,3), (7,2,4), (7,2,5), (7,2,6), (7,2,7)
(7,3,0), (7,3,1), (7,3,2), (7,3,3), (7,3,4), (7,3,5), (7,3,6), (7,3,7)
(7,4,0), (7,4,1), (7,4,2), (7,4,3), (7,4,4), (7,4,5), (7,4,6), (7,4,7)
(7,5,0), (7,5,1), (7,5,2), (7,5,3), (7,5,4), (7,5,5), (7,5,6), (7,5,7)
(7,6,0), (7,6,1), (7,6,2), (7,6,3), (7,6,4), (7,6,5), (7,6,6), (7,6,7)
(7,7,0), (7,7,1), (7,7,2), (7,7,3), (7,7,4), (7,7,5), (7,7,6), (7,7,7)

GPU toArray() result i.e., debugPrint(texBuffer);:

(0,0,0), (1,0,0), (2,0,0), (3,0,0), (4,0,0), (5,0,0), (6,0,0), (7,0,0)
(0,1,0), (1,1,0), (2,1,0), (3,1,0), (4,1,0), (5,1,0), (6,1,0), (7,1,0)
(0,2,0), (1,2,0), (2,2,0), (3,2,0), (4,2,0), (5,2,0), (6,2,0), (7,2,0)
(0,3,0), (1,3,0), (2,3,0), (3,3,0), (4,3,0), (5,3,0), (6,3,0), (7,3,0)
(0,4,0), (1,4,0), (2,4,0), (3,4,0), (4,4,0), (5,4,0), (6,4,0), (7,4,0)
(0,5,0), (1,5,0), (2,5,0), (3,5,0), (4,5,0), (5,5,0), (6,5,0), (7,5,0)
(0,6,0), (1,6,0), (2,6,0), (3,6,0), (4,6,0), (5,6,0), (6,6,0), (7,6,0)
(0,7,0), (1,7,0), (2,7,0), (3,7,0), (4,7,0), (5,7,0), (6,7,0), (7,7,0)
(0,0,0), (1,0,4), (2,4,5), (3,2,4), (4,3,4), (5,4,4), (6,5,4), (7,6,4)
(0,0,1), (1,5,5), (2,1,5), (3,2,5), (4,3,5), (5,4,5), (6,5,5), (7,6,5)
(0,2,1), (1,0,6), (2,1,6), (3,2,6), (4,3,6), (5,4,6), (6,5,6), (7,6,5)
(0,0,3), (1,0,7), (2,1,7), (3,2,7), (4,3,7), (5,4,7), (6,7,5), (7,6,7)
(0,0,0), (1,1,0), (2,2,0), (3,3,0), (4,4,0), (5,0,5), (6,6,0), (7,7,0)
(0,0,1), (1,1,1), (2,2,1), (3,3,1), (4,1,5), (5,5,1), (6,6,1), (7,7,1)
(0,0,2), (1,1,2), (2,2,2), (3,2,5), (4,4,2), (5,5,2), (6,6,2), (7,7,2)
(0,0,3), (1,1,3), (2,3,5), (3,3,3), (4,4,3), (5,5,3), (6,6,3), (7,7,3)
(0,0,0), (1,0,4), (2,0,4), (3,0,4), (4,0,4), (5,0,4), (6,0,4), (7,0,4)
(0,1,1), (1,1,5), (2,1,5), (3,1,5), (4,1,5), (5,1,5), (6,1,5), (7,1,5)
(0,2,2), (1,2,6), (2,2,6), (3,2,6), (4,2,6), (5,2,6), (6,2,6), (7,2,6)
(0,3,3), (1,3,7), (2,3,7), (3,3,7), (4,3,7), (5,3,7), (6,3,7), (7,3,7)
(0,4,0), (1,4,0), (2,4,0), (3,4,0), (4,4,0), (5,4,0), (6,4,0), (7,4,0)
(0,5,1), (1,5,1), (2,5,1), (3,5,1), (4,5,1), (5,5,1), (6,5,1), (7,5,1)
(0,6,2), (1,6,2), (2,6,2), (3,6,2), (4,6,2), (5,6,2), (6,6,2), (7,6,2)
(0,7,3), (1,7,3), (2,7,3), (3,7,3), (4,7,3), (5,7,3), (6,7,3), (7,7,3)
(0,0,3), (1,0,3), (2,0,3), (3,0,3), (4,0,3), (5,0,3), (6,0,3), (7,0,3)
(0,1,3), (1,1,3), (2,1,3), (3,1,3), (4,1,3), (5,1,3), (6,1,3), (7,1,3)
(0,2,3), (1,2,3), (2,2,3), (3,2,3), (4,2,3), (5,2,3), (6,2,3), (7,2,3)
(0,3,3), (1,3,3), (2,3,3), (3,3,3), (4,3,3), (5,3,3), (6,3,3), (7,3,3)
(0,4,3), (1,4,3), (2,4,3), (3,4,3), (4,4,3), (5,4,3), (6,4,3), (7,4,3)
(0,5,3), (1,5,3), (2,5,3), (3,5,3), (4,5,3), (5,5,3), (6,5,3), (7,5,3)
(0,6,3), (1,6,3), (2,6,3), (3,6,3), (4,6,3), (5,6,3), (6,6,3), (7,6,3)
(0,7,3), (1,7,3), (2,7,3), (3,7,3), (4,7,3), (5,7,3), (6,7,3), (7,7,3)
(0,0,4), (1,0,4), (2,0,4), (3,0,4), (4,0,4), (5,0,4), (6,0,4), (7,0,4)
(0,1,4), (1,1,4), (2,1,4), (3,1,4), (4,1,4), (5,1,4), (6,1,4), (7,1,4)
(0,2,4), (1,2,4), (2,2,4), (3,2,4), (4,2,4), (5,2,4), (6,2,4), (7,2,4)
(0,3,4), (1,3,4), (2,3,4), (3,3,4), (4,3,4), (5,3,4), (6,3,4), (7,3,4)
(0,4,4), (1,4,4), (2,4,4), (3,4,4), (4,4,4), (5,4,4), (6,4,4), (7,4,4)
(0,5,4), (1,5,4), (2,5,4), (3,5,4), (4,5,4), (5,5,4), (6,5,4), (7,5,4)
(0,6,4), (1,6,4), (2,6,4), (3,6,4), (4,6,4), (5,6,4), (6,6,4), (7,6,4)
(0,7,4), (1,7,4), (2,7,4), (3,7,4), (4,7,4), (5,7,4), (6,7,4), (7,7,4)
(0,0,0), (1,0,5), (2,1,5), (3,2,5), (4,3,5), (5,5,1), (6,5,5), (7,6,5)
(0,0,1), (1,0,6), (2,1,6), (3,2,6), (4,6,1), (5,4,6), (6,5,6), (7,6,6)
(0,0,2), (1,0,7), (2,1,7), (3,7,1), (4,3,7), (5,4,7), (6,5,7), (7,6,7)
(0,0,0), (1,1,0), (2,0,1), (3,3,0), (4,4,0), (5,5,0), (6,6,0), (7,7,0)
(0,0,1), (1,1,1), (2,2,1), (3,3,1), (4,4,1), (5,5,1), (6,6,1), (7,7,1)
(0,2,1), (1,1,2), (2,2,2), (3,3,2), (4,4,2), (5,5,2), (6,6,2), (7,2,1)
(0,0,3), (1,1,3), (2,2,3), (3,3,3), (4,4,3), (5,5,3), (6,3,1), (7,7,3)
(0,0,4), (1,1,4), (2,2,4), (3,3,4), (4,4,4), (5,4,1), (6,6,4), (7,7,4)
(0,0,0), (1,0,5), (2,0,5), (3,0,5), (4,0,5), (5,0,5), (6,0,5), (7,0,5)
(0,1,1), (1,1,6), (2,1,6), (3,1,6), (4,1,6), (5,1,6), (6,1,6), (7,1,6)
(0,2,2), (1,2,7), (2,2,7), (3,2,7), (4,2,7), (5,2,7), (6,2,7), (7,2,7)
(0,3,0), (1,3,0), (2,3,0), (3,3,0), (4,3,0), (5,3,0), (6,3,0), (7,3,0)
(0,4,1), (1,4,1), (2,4,1), (3,4,1), (4,4,1), (5,4,1), (6,4,1), (7,4,1)
(0,5,2), (1,5,2), (2,5,2), (3,5,2), (4,5,2), (5,5,2), (6,5,2), (7,5,2)
(0,6,3), (1,6,3), (2,6,3), (3,6,3), (4,6,3), (5,6,3), (6,6,3), (7,6,3)
(0,7,4), (1,7,4), (2,7,4), (3,7,4), (4,7,4), (5,7,4), (6,7,4), (7,7,4)
(0,0,7), (1,0,7), (2,0,7), (3,0,7), (4,0,7), (5,0,7), (6,0,7), (7,0,7)
(0,1,7), (1,1,7), (2,1,7), (3,1,7), (4,1,7), (5,1,7), (6,1,7), (7,1,7)
(0,2,7), (1,2,7), (2,2,7), (3,2,7), (4,2,7), (5,2,7), (6,2,7), (7,2,7)
(0,3,7), (1,3,7), (2,3,7), (3,3,7), (4,3,7), (5,3,7), (6,3,7), (7,3,7)
(0,4,7), (1,4,7), (2,4,7), (3,4,7), (4,4,7), (5,4,7), (6,4,7), (7,4,7)
(0,5,7), (1,5,7), (2,5,7), (3,5,7), (4,5,7), (5,5,7), (6,5,7), (7,5,7)
(0,6,7), (1,6,7), (2,6,7), (3,6,7), (4,6,7), (5,6,7), (6,6,7), (7,6,7)
(0,7,7), (1,7,7), (2,7,7), (3,7,7), (4,7,7), (5,7,7), (6,7,7), (7,7,7)

How important is this (1-5)?

Strikes me as a pretty integral issue since there appears to be a non-identical transformation between CPU and GPU buffers.

Expected behavior (i.e. solution)

Those two arrays should be the same (or at least differ by an obvious matrix transform/mapping), instead the toArray() buffer is filled with duplicate data and errors that don't map at all to the original CPU buffer.

Inizia con il percorso degli argomenti createKernel(...), Array3D(3) e bufferTex.toArray() usando la riproduzione 8×8×8 fornita su Node.js/headlessgl. Confronta il buffer della CPU con l'array della texture restituito e traccia la lettura della texture dalla GPU e la mappatura degli indici; il lavoro è completo quando toArray() conserva i valori di input o applica una mappatura coerente.