message: mol-math: fixed makeRotation edge case
diff: @@ -452,9 +452,15 @@ namespace Vec3 {
  }
  const rotTemp = zero();
  + const flipMatrix = Mat4.fromScaling(Mat4.zero(), create(-1, -1, -1))
  export function makeRotation(mat: Mat4, a: Vec3, b: Vec3): Mat4 {
  const by = angle(a, b);
  if (Math.abs(by) < 0.0001) return Mat4.setIdentity(mat);
  + if (Math.abs(by - Math.PI) < EPSILON.Value) {
  + // here, axis can be [0,0,0] but the rotation is a simple flip
  + Mat4.copy(mat, flipMatrix);
  + return mat;
  + }
  const axis = cross(rotTemp, a, b);
  return Mat4.fromRotation(mat, by, axis);
  }
  