/**
* Convert RGB values to HSL (hue/saturation/lightness)
*
* @param rgb range 255 255 255
* @param doRound set to false when just using this for for RGB -- HSL -- HSL' -- RGB' conversion
* @return the HSL as P3 range 360 100 100
* @author hansonr
*/
public static P3 rgbToHSL(P3 rgb, boolean doRound) {
// adapted from http://tips4java.wordpress.com/2009/07/05/hsl-color/
// see http://en.wikipedia.org/wiki/HSL_color_space
float r = rgb.x / 255;
float g = rgb.y / 255;
float b = rgb.z / 255;
float min = Math.min(r, Math.min(g, b));
float max = Math.max(r, Math.max(g, b));
// lightness is just p * 50
float p = (max + min);
float q = (max - min);
float h =
(60
* ((q == 0
? 0
: max == r ? ((g - b) / q + 6) : max == g ? (b - r) / q + 2 : (r - g) / q + 4)))
% 360;
float s = q / (q == 0 ? 1 : p <= 1 ? p : 2 - p);
// we round to tenths for HSL so that we can return enough
// precision to get back 1-255 in RGB
return (doRound
? P3.new3(Math.round(h * 10) / 10f, Math.round(s * 1000) / 10f, Math.round(p * 500) / 10f)
: P3.new3(h, s * 100, p * 50));
}
/**
* Convert HSL (hue/saturation/luninance) values to RGB
*
* @param hsl in the range 360, 100, 100
* @return the RGB as P3 range 0 to 255
* @author hansonr
*/
public static P3 hslToRGB(P3 hsl) {
// adapted from http://tips4java.wordpress.com/2009/07/05/hsl-color/
// see http://en.wikipedia.org/wiki/HSL_color_space
// highly condensed
float h = Math.max(0, Math.min(360, hsl.x)) / 60;
float s = Math.max(0, Math.min(100, hsl.y)) / 100;
float l = Math.max(0, Math.min(100, hsl.z)) / 100;
float p = l - (l < 0.5 ? l : 1 - l) * s;
float q = 2 * (l - p);
float r = toRGB(p, q, h + 2);
float g = toRGB(p, q, h);
float b = toRGB(p, q, h - 2);
return P3.new3(Math.round(r * 255), Math.round(g * 255), Math.round(b * 255));
}
public static final P3 colorPtFromInt(int color, P3 pt) {
if (pt == null) pt = new P3();
pt.set((color >> 16) & 0xFF, (color >> 8) & 0xFF, color & 0xFF);
return pt;
}
