Added color utilities; implemented more of Graph related classes

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@76 0fc631ac-6414-0410-93d0-97cfa31319b6

src/gfx/color.cpp

@@ -0,0 +1,48 @@
+//+----------------------------------------------------------------------------+
+//| Description:  Magic Set Editor - Program to make Magic (tm) cards          |
+//| Copyright:    (C) 2001 - 2006 Twan van Laarhoven                           |
+//| License:      GNU General Public License 2 or later (see file COPYING)     |
+//+----------------------------------------------------------------------------+
+
+// ----------------------------------------------------------------------------- : Includes
+
+#include <gfx/gfx.hpp>
+
+// ----------------------------------------------------------------------------- : Color utility functions
+
+Color lerp(const Color& a, const Color& b, double t) {
+	return Color(a.Red()   + (b.Red()   - a.Red()  ) * t,
+	             a.Green() + (b.Green() - a.Green()) * t,
+	             a.Blue()  + (b.Blue()  - a.Blue() ) * t);
+}
+
+
+int hsl2rgbp(double t1, double t2, double t3) {
+	// adjust t3 to [0...1)
+	if      (t3 < 0.0) t3 += 1;
+	else if (t3 > 1.0) t3 -= 1;
+	// determine color
+	if (6.0 * t3 < 1) return (int)(255 * (t1 + (t2-t1) * 6.0 * t3)             );
+	if (2.0 * t3 < 1) return (int)(255 * (t2)                                  );
+	if (3.0 * t3 < 2) return (int)(255 * (t1 + (t2-t1) * 6.0 * (2.0/3.0 - t3)) );
+	else              return (int)(255 * (t1)                                  );
+}
+Color hsl2rgb(double h, double s, double l) {
+	double t2 = l < 0.5 ? l * (1.0 + s) :
+	                      l * (1.0 - s) + s;
+	double t1 = 2.0 * l - t2;
+	return Color(
+		hsl2rgbp(t1, t2, h + 1.0/3.0),
+		hsl2rgbp(t1, t2, h)          ,
+		hsl2rgbp(t1, t2, h - 1.0/3.0)
+	);
+}
+
+
+Color darken(const Color& c) {
+	return Color(
+		c.Red()   * 8 / 10,
+		c.Green() * 8 / 10,
+		c.Blue()  * 8 / 10
+	);
+}