X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=vrtris;a=blobdiff_plain;f=src%2Fcolor.c;fp=src%2Fcolor.c;h=f1de5f4648fdf152268857755f872fb029542be5;hp=0000000000000000000000000000000000000000;hb=d6638277efddf2fd47de884af174f907789b82ec;hpb=ce8a093ece30d3ab608a52b0247ad7a195cc0cc8

diff --git a/src/color.c b/src/color.c
new file mode 100644
index 0000000..f1de5f4
--- /dev/null
+++ b/src/color.c
@@ -0,0 +1,85 @@
+#include <math.h>
+#include "color.h"
+
+static float min3(float a, float b, float c)
+{
+	if(a < b && a < c) return a;
+	return b < c ? b : c;
+}
+
+static float max3(float a, float b, float c)
+{
+	if(a > b && a > c) return a;
+	return b > c ? b : c;
+}
+
+void rgb_to_hsv(float r, float g, float b, float *h, float *s, float *v)
+{
+	float min, max, delta;
+
+	min = min3(r, g, b);
+	max = max3(r, g, b);
+	*v = max;
+
+	delta = max - min;
+
+	if(max != 0) {
+		*s = delta / max;
+	} else {
+		*s = 0;
+		*h = -1;
+		return;
+	}
+
+	if(!delta) delta = 1.0f;
+
+	if(r == max)
+		*h = (g - b) / delta;
+	else if( g == max )
+		*h = 2 + (b - r) / delta;
+	else
+		*h = 4 + (r - g) / delta;
+
+	*h *= 60;
+	if(*h < 0) {
+		*h += 360.0f;
+	}
+	*h /= 360.0f;
+}
+
+#define RETRGB(red, green, blue) \
+	do { \
+		*r = (red); \
+		*g = (green); \
+		*b = (blue); \
+		return; \
+	} while(0)
+
+void hsv_to_rgb(float h, float s, float v, float *r, float *g, float *b)
+{
+	float sec, frac, o, p, q;
+	int hidx;
+
+	if(s == 0.0f) {
+		*r = *g = *b = v;
+		return;
+	}
+
+	sec = floor(h * (360.0f / 60.0f));
+	frac = (h * (360.0f / 60.0f)) - sec;
+
+	o = v * (1.0f - s);
+	p = v * (1.0f - s * frac);
+	q = v * (1.0f - s * (1.0f - frac));
+
+	hidx = (int)sec;
+	switch(hidx) {
+	default:
+	case 0: RETRGB(v, q, o);
+	case 1: RETRGB(p, v, o);
+	case 2: RETRGB(o, v, q);
+	case 3: RETRGB(o, p, v);
+	case 4: RETRGB(q, o, v);
+	case 5: RETRGB(v, o, p);
+	}
+}