@thi.ng/shader-ast-stdlib/raymarch/scene.js

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

import { V2, V3 } from "@thi.ng/shader-ast/api/types";
import { assign } from "@thi.ng/shader-ast/ast/assign";
import { brk, forLoop, ifThen } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { gensym } from "@thi.ng/shader-ast/ast/idgen";
import { INT0, float, int, vec2 } from "@thi.ng/shader-ast/ast/lit";
import { gt, inc, lt, madd } from "@thi.ng/shader-ast/ast/ops";
import { $x, $y } from "@thi.ng/shader-ast/ast/swizzle";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import { rayPointAt } from "./point-at.js";
const raymarchScene = (scene, _opts) => {
  const opts = {
    name: gensym("raymarchScene_"),
    near: 0.1,
    far: 10,
    steps: 100,
    eps: 0.01,
    bias: 0.7,
    ..._opts
  };
  return defn(V2, opts.name, [V3, V3], (pos, dir) => {
    let total;
    let res;
    return [
      total = sym(float(opts.near)),
      res = sym(V2),
      forLoop(
        sym(INT0),
        (i) => lt(i, int(opts.steps)),
        inc,
        () => [
          assign(res, scene(rayPointAt(pos, dir, total))),
          ifThen(lt($x(res), float(opts.eps)), [
            ret(vec2(total, $y(res)))
          ]),
          assign(total, madd($x(res), float(opts.bias), total)),
          ifThen(gt(total, float(opts.far)), [brk])
        ]
      ),
      ret(vec2(opts.far, 0))
    ];
  });
};
export {
  raymarchScene
};