File size: 2,195 Bytes
fc7d689 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | /**
* Diverging colormap: coolwarm_r (reversed).
* Negative values (compression) -> red/warm
* Positive values (tension) -> blue/cool
* Matches matplotlib coolwarm_r used in the desktop app.
*/
const STOPS = [
[0.0, [0.706, 0.016, 0.150]], // dark red (max compression)
[0.25, [0.929, 0.567, 0.459]],
[0.5, [0.865, 0.865, 0.865]], // neutral gray (zero)
[0.75, [0.557, 0.647, 0.925]],
[1.0, [0.227, 0.298, 0.753]], // dark blue (max tension)
];
function lerp(a, b, t) {
return a + (b - a) * t;
}
export function colormapCoolwarmR(t) {
t = Math.max(0, Math.min(1, t));
for (let i = 0; i < STOPS.length - 1; i++) {
const [t0, c0] = STOPS[i];
const [t1, c1] = STOPS[i + 1];
if (t >= t0 && t <= t1) {
const f = (t - t0) / (t1 - t0);
return [
lerp(c0[0], c1[0], f),
lerp(c0[1], c1[1], f),
lerp(c0[2], c1[2], f),
];
}
}
return STOPS[STOPS.length - 1][1];
}
/**
* Map scalars to colors using diverging colormap centered at 0.
* Returns Float32Array of n*3 RGB values.
*
* This matches PyVista's behavior: symmetric range around 0,
* so pure compression maps to the red half [0 -> 0.5].
*/
export function mapScalarsToColors(values, vmin, vmax) {
const n = values.length;
const colors = new Float32Array(n * 3);
const absMax = Math.max(Math.abs(vmin), Math.abs(vmax)) || 1e-6;
for (let i = 0; i < n; i++) {
// [-absMax, +absMax] -> [0, 1], with 0 -> 0.5
const t = (values[i] / absMax + 1) * 0.5;
const [r, g, b] = colormapCoolwarmR(t);
colors[i * 3] = r;
colors[i * 3 + 1] = g;
colors[i * 3 + 2] = b;
}
return colors;
}
/**
* Create CSS gradient for the colorbar.
* Top = max (blue/tension), bottom = min (red/compression).
*/
export function colormapGradientCSS() {
const stops = [];
for (let i = 0; i <= 20; i++) {
const t = 1 - i / 20;
const [r, g, b] = colormapCoolwarmR(t);
stops.push(`rgb(${r * 255 | 0},${g * 255 | 0},${b * 255 | 0})`);
}
return `linear-gradient(to bottom, ${stops.join(', ')})`;
}
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