color.c

#include "color.h"

#include <math.h>

//Gamma correction table
//From https://learn.adafruit.com/led-tricks-gamma-correction/the-quick-fix
//Article written by Phillip Burgess
const unsigned char gamma8[256] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                   1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3,
                                   4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11,
                                   11, 11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20,
                                   21, 21, 22, 22, 23, 24, 24, 25, 25, 26, 27, 27, 28, 29, 29, 30, 31, 32, 32, 33, 34,
                                   35, 35, 36, 37, 38, 39, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 50, 51, 52,
                                   54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68, 69, 70, 72, 73, 74, 75, 77,
                                   78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 92, 93, 95, 96, 98, 99, 101, 102, 104, 105,
                                   107, 109, 110, 112, 114, 115, 117, 119, 120, 122, 124, 126, 127, 129, 131, 133, 135,
                                   137, 138, 140, 142, 144, 146, 148, 150, 152, 154, 156, 158, 160, 162, 164, 167, 169,
                                   171, 173, 175, 177, 180, 182, 184, 186, 189, 191, 193, 196, 198, 200, 203, 205, 208,
                                   210, 213, 215, 218, 220, 223, 225, 228, 231, 233, 236, 239, 241, 244, 247, 249, 252,
                                   255};

//By Karsten "postspectacular" Schmidt
//From https://gist.github.com/postspectacular/2a4a8db092011c6743a7#file-hsv2rgb-ino-L29
float fract(float x) { return x - (int) x; }

float mix(float a, float b, float t) { return a + (b - a) * t; }

float constrain(float x, float low, float high) { return ((x) < (low) ? (low) : ((x) > (high) ? (high) : (x))); }

float hueToFloat(int _hue) {
    return (float) _hue / HUE_MAX;
}

int valueToInt(float _value) {
    return (int) (_value * 255);
}

float* hsv2rgb(float h, float s, float b, float* rgb) {
    rgb[0] = b * mix(1.0F, constrain(fabsf(fract(h + 1.0F) * 6.0F - 3.0F) - 1.0F, 0.0F, 1.0F), s);
    rgb[1] = b * mix(1.0F, constrain(fabsf(fract(h + 0.6666666F) * 6.0F - 3.0F) - 1.0F, 0.0F, 1.0F), s);
    rgb[2] = b * mix(1.0F, constrain(fabsf(fract(h + 0.3333333F) * 6.0F - 3.0F) - 1.0F, 0.0F, 1.0F), s);
}