Object Frame

1import * as THREE from "three/webgpu";
2import { makePoseAt, SETTLE } from "../core/motion";
3import type { Schedule, Pose } from "../frost";
4export const shapeAt = (t: number, s: Schedule) => (t < s.form1 ? 0 : t < s.form2 ? 1 : 2);
5/** Same parent YXZ motion and settled inverse-facing child as the full Frost block. */
6export function objectFrameAt(
7  t: number,
8  s: Schedule,
9  p: Pose,
10  k = shapeAt(t, s),
11  stationary = false,
12) {
13  const pose = makePoseAt(s, p),
14    at = pose(t),
15    q = (time: number) => {
16      const v = pose(time);
17      return new THREE.Quaternion().setFromEuler(
18        new THREE.Euler((v.pitch * Math.PI) / 180, (v.yaw * Math.PI) / 180, 0, "YXZ"),
19      );
20    };
21  const rotation = stationary ? new THREE.Quaternion() : q(t),
22    facing =
23      stationary || k === 0
24        ? new THREE.Quaternion()
25        : q((k === 1 ? s.form1 : s.form2) + SETTLE).invert();
26  const position = new THREE.Vector3(0, 0.05, stationary ? 0 : at.z);
27  return {
28    rotation,
29    facing,
30    position,
31    matrix: new THREE.Matrix4().compose(
32      position,
33      rotation.clone().multiply(facing),
34      new THREE.Vector3(1, 1, 1),
35    ),
36  };
37}