@thi.ng/shader-ast-stdlib/sdf/tri.js

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

import { F, V2 } from "@thi.ng/shader-ast/api/types";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { vec2 } from "@thi.ng/shader-ast/ast/lit";
import { div, mul, neg, 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 { dot, min, sign, sqrt } from "@thi.ng/shader-ast/builtin/math";
import { clamp01 } from "../math/clamp.js";
import { cross2 } from "../math/cross2.js";
const sdfTriangle2 = defn(
  F,
  "sdTriangle",
  [V2, V2, V2, V2],
  (p, a, b, c) => {
    let e0, e1, e2;
    let v0, v1, v2;
    let pq0, pq1, pq2;
    let s;
    let d;
    const $pq = (v, e) => sub(v, mul(e, clamp01(div(dot(v, e), dot(e, e)))));
    return [
      e0 = sym(sub(b, a)),
      e1 = sym(sub(c, b)),
      e2 = sym(sub(a, c)),
      v0 = sym(sub(p, a)),
      v1 = sym(sub(p, b)),
      v2 = sym(sub(p, c)),
      pq0 = sym($pq(v0, e0)),
      pq1 = sym($pq(v1, e1)),
      pq2 = sym($pq(v2, e2)),
      s = sym(sign(cross2(e0, e2))),
      d = sym(
        min(
          min(
            vec2(dot(pq0, pq0), mul(s, cross2(v0, e0))),
            vec2(dot(pq1, pq1), mul(s, cross2(v1, e1)))
          ),
          vec2(dot(pq2, pq2), mul(s, cross2(v2, e2)))
        )
      ),
      ret(mul(neg(sqrt($x(d))), sign($y(d))))
    ];
  }
);
export {
  sdfTriangle2
};