#5953: Sort OpenGLStates by colour, if all the other checks produced …

…the same result.

Darker state colours will be considered less than the ones with brighter colours.

radiantcore/rendersystem/backend/OpenGLStateLess.h

@@ -5,6 +5,13 @@
 namespace render
 {
 
+// Compare two Colour4 values
+inline bool Colour4_less(const Colour4& a, const Colour4& b)
+{
+    return a.x() * a.x() + a.y() * a.y() + a.z() * a.z() + a.w() * a.w() <
+           b.x() * b.x() + b.y() * b.y() + b.z() * b.z() + b.w() * b.w();
+}
+
 /**
  * Comparison class for OpenGLState objects.
  */
@@ -35,6 +42,11 @@ struct OpenGLStateLess
 	  {
 	    return self->getRenderFlags() < other->getRenderFlags();
 	  }
+      // Sort brighter colours on top if all of the above are equivalent
+      if (self->getColour() != other->getColour())
+      {
+          return Colour4_less(self->getColour(), other->getColour());
+      }
 	  //! Comparing address makes sure states are never equal.
 	  return self < other;
     }