X-Git-Url: https://git.octo.it/?a=blobdiff_plain;ds=sidebyside;f=src%2Fvideo%2Fcolor.hpp;h=e3ff67804b8aa1f9bc615a55b50908914f7fcd93;hb=20efd7620620892d92b1c7df124c3a0c8df22a82;hp=e94b362d0b3a8cdb3105d16321f253db4ad0bd1e;hpb=61c018269ea0a87d562f47eee9fba2f8bb091a70;p=supertux.git

diff --git a/src/video/color.hpp b/src/video/color.hpp
index e94b362d0..e3ff67804 100644
--- a/src/video/color.hpp
+++ b/src/video/color.hpp
@@ -66,6 +66,16 @@ public:
       log_warning << "color value out of range: " << red << ", " << green << ", " << blue << ", " << alpha << std::endl;
   }
 
+  float greyscale() const
+  {
+    return red * 0.30 + green * 0.59 + blue * 0.11;
+  }
+
+  bool operator < (const Color& other) const
+  {
+    return greyscale() < other.greyscale();
+  }
+
   float red, green, blue, alpha;
 };