Environment Sampling

1import { RW } from "../rewrite";
2import { tsl } from "../tsl/t";
3const { normalize, cross, select, abs, vec3, texture, equirectUV, pmremTexture } = tsl;
4type N = any;
5export function iceEnvironment(environment: any, strength: N, direction: N, rough: N) {
6  if (RW.environment) return pmremTexture(environment, direction, rough).rgb.mul(strength);
7  const d = normalize(direction);
8  const tangent = normalize(
9    cross(d, select(abs(d.y).lessThan(0.95), vec3(0, 1, 0), vec3(1, 0, 0))),
10  );
11  const bitangent = cross(d, tangent);
12  const spread = rough.mul(rough).mul(0.32);
13  const sample = (q: N) => texture(environment, equirectUV(normalize(q))).level(0).rgb;
14  return sample(d)
15    .mul(0.4)
16    .add(sample(d.add(tangent.mul(spread))).mul(0.15))
17    .add(sample(d.sub(tangent.mul(spread))).mul(0.15))
18    .add(sample(d.add(bitangent.mul(spread))).mul(0.15))
19    .add(sample(d.sub(bitangent.mul(spread))).mul(0.15))
20    .mul(strength);
21}