1 files changed, 81 insertions, 0 deletions
diff --git a/utils/hsv.c b/utils/hsv.c
new file mode 100644
index 0000000..cf1cc8d
--- /dev/null
+++ b/utils/hsv.c
@@ -0,0 +1,81 @@
+/* xscreensaver, Copyright (c) 1992, 1997 Jamie Zawinski <jwz@jwz.org>
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation.  No representations are made about the suitability of this
+ * software for any purpose.  It is provided "as is" without express or 
+ * implied warranty.
+ */
+
+/* This file contains some utility routines for randomly picking the colors
+   to hack the screen with.
+ */
+
+#include "utils.h"
+#include "hsv.h"
+
+void
+hsv_to_rgb (int h, double s, double v,
+	    unsigned short *r, unsigned short *g, unsigned short *b)
+{
+  double H, S, V, R, G, B;
+  double p1, p2, p3;
+  double f;
+  int i;
+
+  if (s < 0) s = 0;
+  if (v < 0) v = 0;
+  if (s > 1) s = 1;
+  if (v > 1) v = 1;
+
+  S = s; V = v;
+  H = (h % 360) / 60.0;
+  i = H;
+  f = H - i;
+  p1 = V * (1 - S);
+  p2 = V * (1 - (S * f));
+  p3 = V * (1 - (S * (1 - f)));
+  if	  (i == 0) { R = V;  G = p3; B = p1; }
+  else if (i == 1) { R = p2; G = V;  B = p1; }
+  else if (i == 2) { R = p1; G = V;  B = p3; }
+  else if (i == 3) { R = p1; G = p2; B = V;  }
+  else if (i == 4) { R = p3; G = p1; B = V;  }
+  else		   { R = V;  G = p1; B = p2; }
+  *r = R * 65535;
+  *g = G * 65535;
+  *b = B * 65535;
+}
+
+void
+rgb_to_hsv (unsigned short r, unsigned short g, unsigned short b,
+	    int *h, double *s, double *v)
+{
+  double R, G, B, H, S, V;
+  double cmax, cmin;
+  double cmm;
+  int imax;
+  R = ((double) r) / 65535.0;
+  G = ((double) g) / 65535.0;
+  B = ((double) b) / 65535.0;
+  cmax = R; cmin = G; imax = 1;
+  if  ( cmax < G ) { cmax = G; cmin = R; imax = 2; }
+  if  ( cmax < B ) { cmax = B; imax = 3; }
+  if  ( cmin > B ) { cmin = B; }
+  cmm = cmax - cmin;
+  V = cmax;
+  if (cmm == 0)
+    S = H = 0;
+  else
+    {
+      S = cmm / cmax;
+      if       (imax == 1)    H =       (G - B) / cmm;
+      else  if (imax == 2)    H = 2.0 + (B - R) / cmm;
+      else /*if (imax == 3)*/ H = 4.0 + (R - G) / cmm;
+      if (H < 0) H += 6.0;
+    }
+  *h = (H * 60.0);
+  *s = S;
+  *v = V;
+}