+ always ensure first value in gamma table to 0

deps/agg/include/agg_gamma_functions.h

@@ -2,8 +2,8 @@
 // Anti-Grain Geometry - Version 2.4
 // Copyright (C) 2002-2005 Maxim Shemanarev (http://www.antigrain.com)
 //
-// Permission to copy, use, modify, sell and distribute this software 
-// is granted provided this copyright notice appears in all copies. 
+// Permission to copy, use, modify, sell and distribute this software
+// is granted provided this copyright notice appears in all copies.
 // This software is provided "as is" without express or implied
 // warranty, and with no claim as to its suitability for any purpose.
 //
@@ -40,6 +40,7 @@ namespace agg
 
         double operator() (double x) const
         {
+            if (x == 0.0) return 0.0;
             return pow(x, m_gamma);
         }
 
@@ -122,6 +123,3 @@ namespace agg
 }
 
 #endif
-
-
-