@thi.ng/matrices/quat-m33.js

Matrix & quaternion operations for 2D/3D geometry processing

import { setC } from "@thi.ng/vectors/setc";
const quatToMat33 = (out, q) => {
  const [x, y, z, w] = q;
  const x2 = x + x;
  const y2 = y + y;
  const z2 = z + z;
  const xx = x * x2;
  const xy = x * y2;
  const xz = x * z2;
  const yy = y * y2;
  const yz = y * z2;
  const zz = z * z2;
  const wx = w * x2;
  const wy = w * y2;
  const wz = w * z2;
  return setC(
    out || [],
    1 - yy - zz,
    xy + wz,
    xz - wy,
    xy - wz,
    1 - xx - zz,
    yz + wx,
    xz + wy,
    yz - wx,
    1 - xx - yy
  );
};
export {
  quatToMat33
};