我已经使用了很长一段时间-现在不知道它们从何而来…请注意，输入和输出（以度为单位的角度除外）在0到1.0的范围内。
注意：此代码不对输入进行真正的完整性检查。谨慎行事！
typedef struct { double r; // a fraction between 0 and 1 double g; // a fraction between 0 and 1 double b; // a fraction between 0 and 1} rgb;typedef struct { double h; // angle in degrees double s; // a fraction between 0 and 1 double v; // a fraction between 0 and 1} hsv;static hsv rgb2hsv(rgb in);static rgb hsv2rgb(hsv in);hsv rgb2hsv(rgb in){ hsv out; double min, max, delta; min = in.r < in.g ? in.r : in.g; min = min < in.b ? min : in.b; max = in.r > in.g ? in.r : in.g; max = max > in.b ? max : in.b; out.v = max; // v delta = max - min; if (delta < 0.00001) { out.s = 0; out.h = 0; // undefined, maybe nan? return out; } if( max > 0.0 ) { // NOTE: if Max is == 0, this divide would cause a crash out.s = (delta / max); // s } else { // if max is 0, then r = g = b = 0// s = 0, h is undefined out.s = 0.0; out.h = NAN; // its now undefined return out; } if( in.r >= max ) // > is bogus, just keeps compilor happy out.h = ( in.g - in.b ) / delta; // between yellow & magenta else if( in.g >= max ) out.h = 2.0 + ( in.b - in.r ) / delta; // between cyan & yellow else out.h = 4.0 + ( in.r - in.g ) / delta; // between magenta & cyan out.h *= 60.0; // degrees if( out.h < 0.0 ) out.h += 360.0; return out;}rgb hsv2rgb(hsv in){ double hh, p, q, t, ff; long i; rgb out; if(in.s <= 0.0) { // < is bogus, just shuts up warnings out.r = in.v; out.g = in.v; out.b = in.v; return out; } hh = in.h; if(hh >= 360.0) hh = 0.0; hh /= 60.0; i = (long)hh; ff = hh - i; p = in.v * (1.0 - in.s); q = in.v * (1.0 - (in.s * ff)); t = in.v * (1.0 - (in.s * (1.0 - ff))); switch(i) { case 0: out.r = in.v; out.g = t; out.b = p; break; case 1: out.r = q; out.g = in.v; out.b = p; break; case 2: out.r = p; out.g = in.v; out.b = t; break; case 3: out.r = p; out.g = q; out.b = in.v; break; case 4: out.r = t; out.g = p; out.b = in.v; break; case 5: default: out.r = in.v; out.g = p; out.b = q; break; } return out; }
