@thi.ng/shader-ast-stdlib/sdf/bezier.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 { ifThen } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import {
  FLOAT0,
  FLOAT1,
  FLOAT2,
  float,
  vec2
} from "@thi.ng/shader-ast/ast/lit";
import {
  add,
  div,
  gte,
  lt,
  madd,
  mul,
  neg,
  sub
} from "@thi.ng/shader-ast/ast/ops";
import { $x, $y } from "@thi.ng/shader-ast/ast/swizzle";
import { sym } from "@thi.ng/shader-ast/ast/sym";
import {
  abs,
  acos,
  cos,
  dot,
  powf,
  sign,
  sin,
  sqrt
} from "@thi.ng/shader-ast/builtin/math";
import { clamp01 } from "../math/clamp.js";
import { cross2 } from "../math/cross2.js";
const sdfQuadratic2 = defn(
  F,
  "sdfQuadratic2",
  [V2, V2, V2, V2],
  (pos, A, B, C) => {
    let a, b, c, d;
    let kk, kx, ky, kz;
    let p, q, p3, q2, h;
    let m, n, t, v, z;
    let res, sgn;
    let x, y, uv;
    return [
      a = sym(sub(B, A)),
      b = sym(add(madd(B, -2, A), C)),
      c = sym(mul(a, FLOAT2)),
      d = sym(sub(A, pos)),
      kk = sym(div(FLOAT1, dot(b, b))),
      kx = sym(mul(kk, dot(a, b))),
      ky = sym(mul(kk, div(madd(FLOAT2, dot(a, a), dot(d, b)), 3))),
      kz = sym(mul(kk, dot(d, a))),
      res = sym(FLOAT0),
      sgn = sym(FLOAT0),
      p = sym(sub(ky, mul(kx, kx))),
      q = sym(madd(sub(mul(mul(FLOAT2, kx), kx), mul(3, ky)), kx, kz)),
      p3 = sym(mul(mul(p, p), p)),
      q2 = sym(mul(q, q)),
      h = sym(madd(p3, 4, q2)),
      ifThen(
        gte(h, FLOAT0),
        [
          assign(h, sqrt(h)),
          x = sym(div(sub(vec2(h, neg(h)), q), FLOAT2)),
          uv = sym(mul(sign(x), powf(abs(x), float(1 / 3)))),
          t = sym(clamp01(sub(add($x(uv), $y(uv)), kx))),
          assign(x, madd(madd(b, t, c), t, d)),
          assign(res, dot(x, x)),
          assign(sgn, cross2(madd(b, mul(t, FLOAT2), c), x))
        ],
        [
          z = sym(sqrt(neg(p))),
          v = sym(
            div(acos(div(q, mul(mul(p, z), FLOAT2))), float(3))
          ),
          m = sym(cos(v)),
          n = sym(mul(sin(v), Math.sqrt(3))),
          uv = sym(
            clamp01(
              sub(mul(vec2(add(m, m), sub(neg(n), m)), z), kx)
            )
          ),
          x = sym(madd(madd(b, $x(uv), c), $x(uv), d)),
          y = sym(madd(madd(b, $y(uv), c), $y(uv), d)),
          assign(m, dot(x, x)),
          assign(n, dot(y, y)),
          ifThen(
            lt(m, n),
            [
              assign(res, m),
              assign(
                sgn,
                cross2(madd(b, mul($x(uv), FLOAT2), c), x)
              )
            ],
            [
              assign(res, n),
              assign(
                sgn,
                cross2(madd(b, mul($y(uv), FLOAT2), c), y)
              )
            ]
          )
        ]
      ),
      ret(mul(sign(sgn), sqrt(res)))
    ];
  }
);
export {
  sdfQuadratic2
};