Class BatchMatricesAdvanced

The slot matrices of a BatchedMesh3D as one float array, for rewriting many slots a frame

Slot i's matrix is the 16 floats from offset + i * stride, column-major and affine, as setMatrixAt takes it. Call update once you're done, or the writes may never be uploaded:

const { data, stride, offset } = batched.matrices;

for (let i = 0, o = offset; i < batched.size; i++, o += stride) {
  // Rotation and scale live in 0-2, 4-6 and 8-10; translation in 12-14.
  data[o + 12] = x[i];
  data[o + 13] = y[i];
  data[o + 14] = z[i];
}

batched.matrices.update();
Copy

A new slot's matrix is all zeros, so set each full matrix once before writing only the lanes that move. Write only a slot's 16 floats: the floats between matrices hold engine data, such as the slot's material and visibility. Read stride and offset rather than hard-coding them, since the layout can change between releases.