in src/math/Matrix3.ts [82:103]
static RotationFromEuler(m: Vector3): Matrix3 {
const cx = Math.cos(m.x);
const sx = Math.sin(m.x);
const cy = Math.cos(m.y);
const sy = Math.sin(m.y);
const cz = Math.cos(m.z);
const sz = Math.sin(m.z);
const rotationMatrix = [
cy * cz + sy * sx * sz,
-cy * sz + sy * sx * cz,
sy * cx,
cx * sz,
cx * cz,
-sx,
-sy * cz + cy * sx * sz,
sy * sz + cy * sx * cz,
cy * cx,
];
return new Matrix3(...rotationMatrix);
}