@thi.ng/shader-ast-stdlib/sdf/smooth-union.js

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

import { F } from "@thi.ng/shader-ast/api/types";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { FLOAT1 } from "@thi.ng/shader-ast/ast/lit";
import { div, mul, sub } from "@thi.ng/shader-ast/ast/ops";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { mix } from "@thi.ng/shader-ast/builtin/math";
import { clamp01 } from "../math/clamp.js";
import { fit1101 } from "../math/fit.js";
const sdfSmoothUnion = defn(
  F,
  "sdOpSmoothUnion",
  [F, F, F],
  (a, b, k) => {
    let h;
    return [
      h = sym(clamp01(fit1101(div(sub(b, a), k)))),
      ret(sub(mix(b, a, h), mul(mul(k, h), sub(FLOAT1, h))))
    ];
  }
);
const sdfSmoothUnionAll = (k, ...terms) => terms.reduce((acc, x) => sdfSmoothUnion(acc, x, k));
export {
  sdfSmoothUnion,
  sdfSmoothUnionAll
};