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Enable color Temperatures from 1000°K to 2000°K #5

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Enable color Temperatures from 1000°K to 2000°K #5

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41 changes: 27 additions & 14 deletions src/color.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ const REGEX_HEX_6 = new RegExp(HEX_START + HEX_INT_DOUBLE + HEX_INT_DOUBLE + HEX
const REGEX_HEX_8 = new RegExp(HEX_START + HEX_INT_DOUBLE + HEX_INT_DOUBLE + HEX_INT_DOUBLE + HEX_INT_DOUBLE + '$');

// Kelvin temperature bounds
const KELVIN_MIN = 2000;
const KELVIN_MIN = 1000;
const KELVIN_MAX = 40000;

// Math shorthands
Expand Down Expand Up @@ -295,8 +295,9 @@ export class IroColor {
/**
* @desc Convert a kelvin temperature to an approx, RGB value
* @param kelvin - kelvin temperature
* @param realValues - flag to issue real values instead integers
*/
public static kelvinToRgb(kelvin: number): RgbColor {
public static kelvinToRgb(kelvin: number, realValues = false): RgbColor {
const temp = kelvin / 100;
let r, g, b;
if (temp < 66) {
Expand All @@ -309,9 +310,9 @@ export class IroColor {
b = 255
}
return {
r: clamp(floor(r), 0, 255),
g: clamp(floor(g), 0, 255),
b: clamp(floor(b), 0, 255)
r: clamp(realValues ? r : floor(r), 0, 255),
g: clamp(realValues ? g : floor(g), 0, 255),
b: clamp(realValues ? b : floor(b), 0, 255)
};
}

Expand All @@ -322,16 +323,28 @@ export class IroColor {
public static rgbToKelvin(rgb: RgbColor): number {
const { r, g, b } = rgb;
const eps = 0.4;
let minTemp = KELVIN_MIN;
let maxTemp = KELVIN_MAX;
let minTemp = (b>0) ? 2000 : KELVIN_MIN;
let maxTemp = (b>0) ? KELVIN_MAX : 2000;
let temp;
while (maxTemp - minTemp > eps) {
temp = (maxTemp + minTemp) * 0.5;
const rgb = IroColor.kelvinToRgb(temp);
if ((rgb.b / rgb.r) >= (b / r)) {
maxTemp = temp;
} else {
minTemp = temp;
if (b>0) { // temperatures expected to be over 2000k
while (maxTemp - minTemp > eps) {
temp = (maxTemp + minTemp) * 0.5;
const rgb = IroColor.kelvinToRgb(temp, true); // get results in real values
if (rgb.b / rgb.r >= b / r) {
maxTemp = temp;
} else {
minTemp = temp;
}
}
} else { // below 2000k where blue is 0 and red is 255 only green is relevant;
while (maxTemp - minTemp > eps) {
temp = (maxTemp + minTemp) * 0.5;
const rgb = IroColor.kelvinToRgb(temp, true); // get results in real values
if (rgb.g >= g) {
maxTemp = temp;
} else {
minTemp = temp;
}
}
}
return temp;
Expand Down