--- a/include/utils.hpp	Wed Nov 11 12:01:43 2009 -0500
+++ b/include/utils.hpp	Wed Nov 11 23:25:23 2009 -0500
@@ -1,6 +1,19 @@
 #ifndef UTILS_HPP
 #define UTILS_HPP
 
+static const double pi = 3.14159265358979323846;
 
+inline double square(const int& a) { return a*a;}
+
+/** Implements key bindings, for example for cvWaitKey(). */
+inline bool forwardKey(const int& pressedKey) { return (((char)pressedKey) == '+');}
+
+inline bool backwardKey(const int& pressedKey) { return (((char)pressedKey) == '-');}
+
+inline bool saveKey(const int& pressedKey) { return (((char)pressedKey) == 's' || ((char)pressedKey) == 'S');}
+
+inline bool interruptionKey(const int& pressedKey) { return (((char)pressedKey) == 'q' || ((char)pressedKey) == 'Q');}
+
+inline bool skipKey(const int& pressedKey) { return (((char)pressedKey) == 'n' || ((char)pressedKey) == 'N');}
 
 #endif