@thi.ng/shader-ast-stdlib/color/levels.js

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

import { F, M3, V2, V3 } from "@thi.ng/shader-ast/api/types";
import { ternary } from "@thi.ng/shader-ast/ast/controlflow";
import { defn, ret } from "@thi.ng/shader-ast/ast/function";
import { indexMat } from "@thi.ng/shader-ast/ast/indexed";
import {
  FLOAT0,
  FLOAT05,
  FLOAT1,
  VEC3_0,
  VEC3_1,
  float,
  vec3
} from "@thi.ng/shader-ast/ast/lit";
import { lt, madd, mul, reciprocal, sub } from "@thi.ng/shader-ast/ast/ops";
import { $x, $y, $z } from "@thi.ng/shader-ast/ast/swizzle";
import { max, min, pow } from "@thi.ng/shader-ast/builtin/math";
import { fit01, fitClamped } from "../math/fit.js";
const midLevelGamma = defn(F, "midLevelGamma", [F], (mid) => [
  ret(
    reciprocal(
      ternary(
        lt(mid, FLOAT05),
        min(float(9.99), madd(float(9), sub(1, mul(mid, 2)), 1)),
        max(float(0.01), sub(1, sub(mul(mid, 2), 1)))
      )
    )
  )
]);
const midLevelGammaRGB = (mid) => vec3(
  midLevelGamma($x(mid)),
  midLevelGamma($y(mid)),
  midLevelGamma($z(mid))
);
const levelAdjustGamma = defn(
  F,
  "levelAdjustGamma",
  [F, F, V2, V2],
  (x, gamma, input, output) => [
    ret(
      fit01(
        pow(fitClamped(x, $x(input), $y(input), FLOAT0, FLOAT1), gamma),
        $x(output),
        $y(output)
      )
    )
  ]
);
const levelAdjustGammaRGB = defn(
  V3,
  "levelAdjustGammaRGB",
  [V3, V3, M3, M3],
  (x, gamma, input, output) => [
    ret(
      fit01(
        pow(
          fitClamped(
            x,
            indexMat(input, 0),
            indexMat(input, 1),
            VEC3_0,
            VEC3_1
          ),
          gamma
        ),
        indexMat(output, 0),
        indexMat(output, 1)
      )
    )
  ]
);
const levelAdjustMid = (x, mid, input, output) => levelAdjustGamma(x, midLevelGamma(mid), input, output);
const levelAdjustMidRGB = (x, mid, input, output) => levelAdjustGammaRGB(x, midLevelGammaRGB(mid), input, output);
export {
  levelAdjustGamma,
  levelAdjustGammaRGB,
  levelAdjustMid,
  levelAdjustMidRGB,
  midLevelGamma,
  midLevelGammaRGB
};