@thi.ng/shader-ast-stdlib/sdf/polyline.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 } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { index } from "@thi.ng/shader-ast/ast/indexed";
import { INT0, float, int } from "@thi.ng/shader-ast/ast/lit";
import { add, inc, lt } from "@thi.ng/shader-ast/ast/ops";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { min } from "@thi.ng/shader-ast/builtin/math";
import { sdfLine2 } from "./line.js";
const sdfPolyline2 = (N) => defn(
  F,
  `sdfPolyline2_${N}`,
  [V2, ["vec2[]", "pts", { num: N }]],
  (p, pts) => {
    let minD;
    return [
      minD = sym(float(1e6)),
      forLoop(
        sym(INT0),
        (i) => lt(i, int(N - 1)),
        inc,
        (i) => [
          assign(
            minD,
            min(
              minD,
              sdfLine2(
                p,
                index(pts, i),
                index(pts, add(i, 1))
              )
            )
          )
        ]
      ),
      ret(minD)
    ];
  }
);
export {
  sdfPolyline2
};