Simplyfied colors.js

src/common/util/colors.js

@@ -1,83 +1,31 @@
-/*
- * Polynomial approximation for the Turbo colormap
- * Original GLSL implementation:
- *   https://gist.github.com/mikhailov-work/0d177465a8151eb6ede1768d51d476c7
- * Original LUT:
- *   https://gist.github.com/mikhailov-work/ee72ba4191942acecc03fe6da94fc73f
- *
- * Adapted to JavaScript by Kalabint
- *
- * Authors:
- *   Colormap Design: Anton Mikhailov (mikhailov@google.com)
- *   GLSL Approximation: Ruofei Du (ruofei@google.com)
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * SPDX-License-Identifier: Apache-2.0
- */
-
-function interpolateTurbo(t) {
-  t = Math.max(0, Math.min(1, t)); // Clamp t to [0, 1]
-  const r = Math.round(255 * interpolateTurbo_srgb_fn_r(t));
-  const g = Math.round(255 * interpolateTurbo_srgb_fn_g(t));
-  const b = Math.round(255 * interpolateTurbo_srgb_fn_b(t));
-  return [r, g, b];
-}
-
-function interpolateTurbo_srgb_fn_r(t) {
-  const t2 = t * t;
-  const t3 = t2 * t;
-  const t4 = t2 * t2;
-  const t5 = t3 * t2;
-  return (
-    0.13572138 +
-    4.61539260 * t -
-    42.66032258 * t2 +
-    132.13108234 * t3 -
-    152.94239396 * t4 +
-    59.28637943 * t5
-  );
-}
+// Turbo Colormap
+const turboPolynomials = {
+  r: [0.13572138, 4.61539260, -42.66032258, 132.13108234, -152.94239396, 59.28637943],
+  g: [0.09140261, 2.19418839, 4.84296658, -14.18503333, 4.27729857, 2.82956604],
+  b: [0.10667330, 12.64194608, -60.58204836, 110.36276771, -89.90310912, 27.34824973]
+};
 
-function interpolateTurbo_srgb_fn_g(t) {
-  const t2 = t * t;
-  const t3 = t2 * t;
-  const t4 = t2 * t2;
-  const t5 = t3 * t2;
-  return (
-    0.09140261 +
-    2.19418839 * t +
-    4.84296658 * t2 -
-    14.18503333 * t3 +
-    4.27729857 * t4 +
-    2.82956604 * t5
-  );
+function interpolateChannel(t, coeffs) {
+  let result = 0;
+  let tPower = 1;
+  for (let i = 0; i < coeffs.length; i++) {
+    result += coeffs[i] * tPower;
+    tPower *= t;
+  }
+  return Math.max(0, Math.min(1, result));
 }
 
-function interpolateTurbo_srgb_fn_b(t) {
-  const t2 = t * t;
-  const t3 = t2 * t;
-  const t4 = t2 * t2;
-  const t5 = t3 * t2;
-  return (
-    0.10667330 +
-    12.64194608 * t -
-    60.58204836 * t2 +
-    110.36276771 * t3 -
-    89.90310912 * t4 +
-    27.34824973 * t5
-  );
+function interpolateTurbo(t) {
+  t = Math.max(0, Math.min(1, t));
+  return [
+    Math.round(255 * interpolateChannel(t, turboPolynomials.r)),
+    Math.round(255 * interpolateChannel(t, turboPolynomials.g)),
+    Math.round(255 * interpolateChannel(t, turboPolynomials.b))
+  ];
 }
 
-export const getSpeedColor = (speed, max) => {
-  let factor = speed / max;
-  if (factor > 1) factor = 1;
-  if (factor < 0) factor = 0;
-
+export function getSpeedColor(speed, max) {
+  const factor = Math.max(0, Math.min(1, speed / max));
   const [r, g, b] = interpolateTurbo(factor);
   return `rgb(${r}, ${g}, ${b})`;
-};
+}