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56 lines
1.6 KiB
56 lines
1.6 KiB
import { fn } from '../../Nodes.js';
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// Original shader code from:
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// https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/libraries/stdlib/genglsl/lib/mx_hsv.glsl
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export const mx_hsvtorgb = fn( `vec3 mx_hsvtorgb(vec3 hsv)
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{
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// Reference for this technique: Foley & van Dam
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float h = hsv.x; float s = hsv.y; float v = hsv.z;
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if (s < 0.0001f) {
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return vec3 (v, v, v);
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} else {
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h = 6.0f * (h - floor(h)); // expand to [0..6)
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int hi = int(trunc(h));
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float f = h - float(hi);
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float p = v * (1.0f-s);
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float q = v * (1.0f-s*f);
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float t = v * (1.0f-s*(1.0f-f));
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if (hi == 0)
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return vec3 (v, t, p);
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else if (hi == 1)
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return vec3 (q, v, p);
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else if (hi == 2)
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return vec3 (p, v, t);
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else if (hi == 3)
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return vec3 (p, q, v);
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else if (hi == 4)
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return vec3 (t, p, v);
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return vec3 (v, p, q);
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}
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}` );
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export const mx_rgbtohsv = fn( `vec3 mx_rgbtohsv(vec3 c)
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{
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// See Foley & van Dam
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float r = c.x; float g = c.y; float b = c.z;
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float mincomp = min (r, min(g, b));
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float maxcomp = max (r, max(g, b));
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float delta = maxcomp - mincomp; // chroma
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float h, s, v;
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v = maxcomp;
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if (maxcomp > 0.0f)
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s = delta / maxcomp;
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else s = 0.0f;
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if (s <= 0.0f)
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h = 0.0f;
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else {
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if (r >= maxcomp) h = (g-b) / delta;
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else if (g >= maxcomp) h = 2.0f + (b-r) / delta;
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else h = 4.0f + (r-g) / delta;
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h *= (1.0f/6.0f);
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if (h < 0.0f)
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h += 1.0f;
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}
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return vec3(h, s, v);
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}` );
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