@thi.ng/shader-ast-stdlib/viz/function.js

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

import { F, V2 } from "@thi.ng/shader-ast/api/types";
import { assign } from "@thi.ng/shader-ast/ast/assign";
import { forLoop, ifThen } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import {
  FLOAT0,
  FLOAT2,
  VEC2_0,
  VEC2_1,
  float,
  vec2
} from "@thi.ng/shader-ast/ast/lit";
import {
  add,
  addSelf,
  div,
  gt,
  inc,
  lt,
  lte,
  or,
  sub
} from "@thi.ng/shader-ast/ast/ops";
import { $x, $y } from "@thi.ng/shader-ast/ast/swizzle";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { fit } from "../math/fit.js";
const functionSampler = (fn, map, opts = {}) => {
  const { min = 0, max = 1, radius = 1, steps = 4, area = false } = opts;
  return defn(F, void 0, [V2, V2], (frag, res) => {
    let count, total;
    let q;
    const invStep = float(2 * radius / steps);
    return [
      q = sym(map(frag, res)),
      // bail out early if outside [min..max] interval
      ifThen(or(lt($x(q), float(min)), gt($x(q), float(max))), [
        ret(FLOAT0)
      ]),
      count = sym(FLOAT0),
      total = sym(FLOAT0),
      forLoop(
        sym(float(-radius)),
        (x) => lte(x, float(radius)),
        (x) => addSelf(x, invStep),
        (x) => [
          forLoop(
            sym(float(-radius)),
            (y) => lte(y, float(radius)),
            (y) => addSelf(y, invStep),
            (y) => [
              inc(total),
              assign(q, map(add(frag, vec2(x, y)), res)),
              ifThen(gt(fn($x(q)), $y(q)), [inc(count)])
            ]
          )
        ]
      ),
      ...!area ? [
        ifThen(gt(count, div(total, FLOAT2)), [
          assign(count, sub(total, count))
        ])
      ] : [],
      ret(div(count, total))
    ];
  });
};
const functionDomainMapper = (amin, amax, bmin = VEC2_0, bmax = VEC2_1) => defn(V2, void 0, [V2, V2], (p, res) => [
  ret(fit(div(p, res), amin, amax, bmin, bmax))
]);
export {
  functionDomainMapper,
  functionSampler
};