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specs: Simple mixbox implementation.
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6 files changed

+203
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lines changed

‎src/libs/karm-gfx/color.h

+6-3
Original file line numberDiff line numberDiff line change
@@ -26,11 +26,14 @@ struct Color {
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return {red, green, blue, alpha};
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}
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ALWAYS_INLINE constexpr Color() : red(0), green(0), blue(0), alpha(0) {}
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ALWAYS_INLINE constexpr Color()
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: red(0), green(0), blue(0), alpha(0) {}
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ALWAYS_INLINE constexpr Color(u8 red, u8 green, u8 blue, u8 alpha = 255) : red(red), green(green), blue(blue), alpha(alpha) {}
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ALWAYS_INLINE constexpr Color(u8 red, u8 green, u8 blue, u8 alpha = 255)
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: red(red), green(green), blue(blue), alpha(alpha) {}
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ALWAYS_INLINE constexpr Color(Math::Vec4u v) : red(v.x), green(v.y), blue(v.z), alpha(v.w) {}
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ALWAYS_INLINE constexpr Color(Math::Vec4u v)
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: red(v.x), green(v.y), blue(v.z), alpha(v.w) {}
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ALWAYS_INLINE constexpr Color blendOver(Color const background) const {
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if (alpha == 0xff) {

‎src/specs/mixbox/lut.c

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[[gnu::used]] unsigned char const _Mixbox_LUT[] = {
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#include "lut.inc"
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};
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[[gnu::used]] unsigned long long int const _Mixbox_LUT_size = sizeof(_Mixbox_LUT);

‎src/specs/mixbox/lut.inc

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‎src/specs/mixbox/manifest.json

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{
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"$schema": "https://schemas.cute.engineering/stable/cutekit.manifest.component.v1",
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"id": "mixbox-spec",
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"type": "lib",
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"description": "Mixbox is a library for natural color mixing based on real pigments",
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"requires": [
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"karm-io"
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]
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}

‎src/specs/mixbox/mixbox.cpp

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#include "mixbox.h"
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extern "C" unsigned char const _Mixbox_LUT[];
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extern "C" unsigned long long int const _Mixbox_LUT_size;
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namespace Mixbox {
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Bytes const LUT = Bytes(_Mixbox_LUT, _Mixbox_LUT_size);
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static f64 srgb2linear(f64 srgb) {
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if (srgb <= 0.04045f)
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return srgb / 12.92f;
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return ::pow((srgb + 0.055f) / 1.055f, 2.4f);
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}
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static Math::Vec3f srgb2linear(Gfx::Color color) {
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return {
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srgb2linear(color.red / 255.0),
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srgb2linear(color.green / 255.0),
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srgb2linear(color.blue / 255.0),
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};
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}
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static f64 linear2srgb(f64 linear) {
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if (linear <= 0.0031308f)
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return linear * 12.92f;
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return 1.055f * ::pow(linear, 1.0f / 2.4f) - 0.055f;
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}
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static Gfx::Color linear2srgb(Math::Vec3f linear) {
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return {
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static_cast<u8>(linear2srgb(linear[0]) * 255.0),
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static_cast<u8>(linear2srgb(linear[1]) * 255.0),
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static_cast<u8>(linear2srgb(linear[2]) * 255.0),
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255,
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};
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}
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static Math::Vec3f evalPolynomial(f64 c0, f64 c1, f64 c2, f64 c3) {
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auto c00 = c0 * c0;
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auto c11 = c1 * c1;
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auto c22 = c2 * c2;
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auto c33 = c3 * c3;
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auto c01 = c0 * c1;
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auto c02 = c0 * c2;
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auto c12 = c1 * c2;
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auto r = 0.0, g = 0.0, b = 0.0;
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// clang-format off
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auto w00 = c0 * c00; r += 0.07717053*w00; g += 0.02826978*w00; b += 0.24832992*w00;
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auto w01 = c1 * c11; r += 0.95912302*w01; g += 0.80256528*w01; b += 0.03561839*w01;
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auto w02 = c2 * c22; r += 0.74683774*w02; g += 0.04868586*w02; b += 0.00000000*w02;
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auto w03 = c3 * c33; r += 0.99518138*w03; g += 0.99978149*w03; b += 0.99704802*w03;
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auto w04 = c00 * c1; r += 0.04819146*w04; g += 0.83363781*w04; b += 0.32515377*w04;
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auto w05 = c01 * c1; r += -0.68146950*w05; g += 1.46107803*w05; b += 1.06980936*w05;
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auto w06 = c00 * c2; r += 0.27058419*w06; g += -0.15324870*w06; b += 1.98735057*w06;
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auto w07 = c02 * c2; r += 0.80478189*w07; g += 0.67093710*w07; b += 0.18424500*w07;
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auto w08 = c00 * c3; r += -0.35031003*w08; g += 1.37855826*w08; b += 3.68865000*w08;
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auto w09 = c0 * c33; r += 1.05128046*w09; g += 1.97815239*w09; b += 2.82989073*w09;
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auto w10 = c11 * c2; r += 3.21607125*w10; g += 0.81270228*w10; b += 1.03384539*w10;
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auto w11 = c1 * c22; r += 2.78893374*w11; g += 0.41565549*w11; b += -0.04487295*w11;
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auto w12 = c11 * c3; r += 3.02162577*w12; g += 2.55374103*w12; b += 0.32766114*w12;
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auto w13 = c1 * c33; r += 2.95124691*w13; g += 2.81201112*w13; b += 1.17578442*w13;
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auto w14 = c22 * c3; r += 2.82677043*w14; g += 0.79933038*w14; b += 1.81715262*w14;
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auto w15 = c2 * c33; r += 2.99691099*w15; g += 1.22593053*w15; b += 1.80653661*w15;
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auto w16 = c01 * c2; r += 1.87394106*w16; g += 2.05027182*w16; b += -0.29835996*w16;
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auto w17 = c01 * c3; r += 2.56609566*w17; g += 7.03428198*w17; b += 0.62575374*w17;
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auto w18 = c02 * c3; r += 4.08329484*w18; g += -1.40408358*w18; b += 2.14995522*w18;
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auto w19 = c12 * c3; r += 6.00078678*w19; g += 2.55552042*w19; b += 1.90739502*w19;
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// clang-format on
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return {r, g, b};
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}
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Latent unmix(Math::Vec3f rgb) {
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auto r01 = clamp01(rgb[0]);
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auto g01 = clamp01(rgb[1]);
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auto b01 = clamp01(rgb[2]);
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auto x = r01 * 63.0;
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auto y = g01 * 63.0;
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auto z = b01 * 63.0;
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isize ix = x;
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isize iy = y;
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isize iz = z;
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auto tx = x - ((f64)ix);
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auto ty = y - ((f64)iy);
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auto tz = z - ((f64)iz);
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auto lut = next(LUT, (((ix + iy * 64 + iz * 64 * 64) & 0x3FFFF) * 3));
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auto c0 = 0.0;
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auto c1 = 0.0;
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auto c2 = 0.0;
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// clang-format off
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auto w0 = (1.0 - tx) * (1.0 - ty) * (1.0 - tz); c0 += w0 * lut[ 192]; c1 += w0 * lut[ 193]; c2 += w0 * lut[ 194];
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auto w1 = ( tx) * (1.0 - ty) * (1.0 - tz); c0 += w1 * lut[ 195]; c1 += w1 * lut[ 196]; c2 += w1 * lut[ 197];
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auto w2 = (1.0 - tx) * ( ty) * (1.0 - tz); c0 += w2 * lut[ 384]; c1 += w2 * lut[ 385]; c2 += w2 * lut[ 386];
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auto w3 = ( tx) * ( ty) * (1.0 - tz); c0 += w3 * lut[ 387]; c1 += w3 * lut[ 388]; c2 += w3 * lut[ 389];
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auto w4 = (1.0 - tx) * (1.0 - ty) * ( tz); c0 += w4 * lut[12480]; c1 += w4 * lut[12481]; c2 += w4 * lut[12482];
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auto w5 = ( tx) * (1.0 - ty) * ( tz); c0 += w5 * lut[12483]; c1 += w5 * lut[12484]; c2 += w5 * lut[12485];
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auto w6 = (1.0 - tx) * ( ty) * ( tz); c0 += w6 * lut[12672]; c1 += w6 * lut[12673]; c2 += w6 * lut[12674];
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auto w7 = ( tx) * ( ty) * ( tz); c0 += w7 * lut[12675]; c1 += w7 * lut[12676]; c2 += w7 * lut[12677];
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// clang-format on
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c0 *= 1.0 / 255.0;
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c1 *= 1.0 / 255.0;
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c2 *= 1.0 / 255.0;
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auto c3 = 1.0 - (c0 + c1 + c2);
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auto mixrgb = evalPolynomial(c0, c1, c2, c3);
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return {c0, c1, c2, c3,
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r01 - mixrgb[0], g01 - mixrgb[1], b01 - mixrgb[2]};
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}
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Math::Vec3f mix(Latent latent) {
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auto rgb = evalPolynomial(
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latent[0], latent[1], latent[2], latent[3]);
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return {
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clamp01(rgb[0] + latent[4]),
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clamp01(rgb[1] + latent[5]),
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clamp01(rgb[2] + latent[6]),
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};
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}
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Latent unmixColor(Gfx::Color color) {
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return unmix(srgb2linear(color));
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}
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Gfx::Color mixColor(Latent latent) {
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return linear2srgb(mix(latent));
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};
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Math::Vec3f lerp(Math::Vec3f a, Math::Vec3f b, f64 t) {
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auto la = unmix(a);
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auto lb = unmix(b);
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for (usize i = 0; i < LATENT_SIZE; i++) {
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la[i] = ::lerp(la[i], lb[i], t);
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}
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return mix(la);
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}
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Gfx::Color lerpColor(Gfx::Color a, Gfx::Color b, f64 t) {
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return linear2srgb(
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lerp(
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srgb2linear(a),
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srgb2linear(b), t));
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}
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} // namespace Mixbox

‎src/specs/mixbox/mixbox.h

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#pragma once
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#include <karm-gfx/color.h>
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namespace Mixbox {
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static constexpr auto LATENT_SIZE = 7;
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using Latent = Array<f64, LATENT_SIZE>;
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Latent unmix(Math::Vec3f rgb);
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Math::Vec3f mix(Latent latent);
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Latent unmixColor(Gfx::Color color);
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Gfx::Color mixColor(Latent latent);
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Math::Vec3f lerp(Math::Vec3f a, Math::Vec3f b, f64 t);
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Gfx::Color lerpColor(Gfx::Color a, Gfx::Color b, f64 t);
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} // namespace Mixbox

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