@thi.ng/shader-ast-stdlib/noise/fbm.js

Function collection for modular GPGPU / shader programming with @thi.ng/shader-ast

import { S3D, V3, V4 } from "@thi.ng/shader-ast/api/types";
import { forLoop } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { FLOAT05, UINT0, uint, vec4 } from "@thi.ng/shader-ast/ast/lit";
import {
  addSelf,
  div,
  inc,
  lt,
  mul,
  mulSelf
} from "@thi.ng/shader-ast/ast/ops";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { texture } from "@thi.ng/shader-ast/builtin/texture";
const fbmNoiseVec34 = (octaves, decay = 1 / octaves) => defn(V4, null, [S3D, V3], (tex, p) => {
  let res;
  let amp;
  return [
    res = sym(vec4()),
    amp = sym(FLOAT05),
    forLoop(
      sym(UINT0),
      (i) => lt(i, uint(octaves)),
      inc,
      () => [
        addSelf(res, mul(texture(tex, div(p, amp)), amp)),
        mulSelf(amp, decay)
      ]
    ),
    ret(res)
  ];
});
export {
  fbmNoiseVec34
};