@thi.ng/shader-ast-stdlib/noise/voronoi2.js

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

import { F, V2 } 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 {
  FLOAT0,
  SQRT2,
  float,
  int,
  vec2,
  vec3
} from "@thi.ng/shader-ast/ast/lit";
import {
  add,
  addSelf,
  div,
  inc,
  lte,
  mul,
  sub
} from "@thi.ng/shader-ast/ast/ops";
import { $xy, $z } from "@thi.ng/shader-ast/ast/swizzle";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import {
  dot,
  floor,
  fract,
  pow,
  smoothstep,
  sqrt
} from "@thi.ng/shader-ast/builtin/math";
import { hash32 } from "./hash.js";
const voronoise2 = defn(F, "voronoise2", [V2, F, F], (x, u, v) => {
  let p;
  let f;
  let coeff;
  let k;
  let va;
  let wt;
  let g;
  let o;
  let r;
  let w;
  return [
    p = sym(floor(x)),
    f = sym(fract(x)),
    coeff = sym(vec3(u, u, 1)),
    k = sym(add(1, mul(63, pow(sub(1, v), float(4))))),
    va = sym(FLOAT0),
    wt = sym(FLOAT0),
    forLoop(
      sym(int(-2)),
      (i) => lte(i, int(2)),
      inc,
      (i) => [
        forLoop(
          sym(int(-2)),
          (j) => lte(j, int(2)),
          inc,
          (j) => [
            g = sym(vec2(float(i), float(j))),
            o = sym(mul(hash32(add(p, g)), coeff)),
            r = sym(add(sub(g, f), $xy(o))),
            w = sym(
              pow(
                sub(
                  1,
                  smoothstep(FLOAT0, SQRT2, sqrt(dot(r, r)))
                ),
                k
              )
            ),
            addSelf(va, mul(w, $z(o))),
            addSelf(wt, w)
          ]
        )
      ]
    ),
    ret(div(va, wt))
  ];
});
export {
  voronoise2
};