Return Groups

1/** Spatial return groups, evaluated once per retarget, never in the flight integrator. */
2import { tsl } from "../tsl/t";
3import { hash31, voronoiCell, gnoise } from "../tsl/noise";
4import preset from "../../presets/approved-material.json";
5const { max, float, length, sqrt, log, select, smoothstep, vec3, dot, abs, cos, sin, clamp, mix } =
6  tsl;
7export const RETURN_GROUP_DEFAULTS = {
8  returnGroupStagger: preset.returnGroupStagger,
9  returnGroupScale: preset.returnGroupScale,
10  returnGroupSeed: preset.returnGroupSeed,
11  returnNoiseAmount: 2,
12  assemblyFrontDuration: 3.2,
13  assemblyOriginX: -0.65,
14  assemblyOriginY: 0.55,
15  assemblyAngle: -35,
16  assemblySpread: 0.65,
17  assemblyFrontNoise: 0.35,
18  assemblySpeedVariation: 0.65,
19  assemblyBend: 1.2,
20  assemblySwirl: 1.1,
21  assemblyLandingVariation: 0.8,
22};
23export function returnGroupPhase(p: any, scale: any, seed: any, noiseAmount: any = float(0)) {
24  const cell = voronoiCell(p.div(max(scale, 0.1)), seed);
25  const q = p.div(max(scale, 0.1)).add(vec3(seed.mul(0.173), seed.mul(0.317), seed.mul(0.571)));
26  const noise = smoothstep(0.18, 0.82, gnoise(q).mul(0.5).add(0.5));
27  return select(noiseAmount.greaterThan(0.5), noise, hash31(cell.xyz.add(11.7)));
28}
29/** Conservative travel + settling allowance, used only to limit *additional* delay.
30 * Flight parameters and existing wave timing are never changed by the group control. */
31export function returnReserve(distance: any, speed: any, u: any) {
32  const frequency = sqrt(max(u.springK, 0.5));
33  const envelope = distance.add(speed.div(frequency)).add(0.03);
34  return max(
35    float(2.8),
36    u.springRamp
37      .add(distance.div(max(u.returnMaxSpeed, 1)))
38      .add(
39        log(max(envelope.div(max(u.landRadius, 0.001)), 1)).div(
40          max(frequency.mul(u.springDamp), 0.5),
41        ),
42      )
43      .add(0.35),
44  );
45}
46
47/** A travelling seam spreads sideways, like the breakup brush. Object-space field,
48 * evaluated only at retarget; packed into the existing threshold slot. */
49export function assemblyFrontPhase(p: any, u: any) {
50  const q = p.div(max(u.bound, 0.001)).sub(vec3(u.frontX, u.frontY, 0));
51  const angle = u.frontAngle.mul(Math.PI / 180);
52  const along = dot(q.xy, vec3(cos(angle), sin(angle), 0).xy);
53  const across = abs(dot(q.xy, vec3(sin(angle).negate(), cos(angle), 0).xy));
54  // Behind the start grows too, at a slower rate; no disconnected glyph is excluded.
55  const travel = max(along, 0).add(max(along.negate(), 0).mul(1.4)).div(1.5);
56  const spread = across.div(1.5);
57  const noise = gnoise(p.div(max(u.groupScale, 0.1)).add(u.groupSeed.mul(0.173)))
58    .mul(0.5)
59    .add(0.5);
60  return clamp(mix(travel, spread, u.frontSpread).add(noise.mul(u.frontNoise).mul(0.35)), 0, 1);
61}