Fixed trunc implementation

glm/core/func_common.inl

@@ -189,7 +189,7 @@ namespace glm
     inline genType trunc(genType const & x)
     {
 		GLM_STATIC_ASSERT(detail::type<genType>::is_float);
-        return floor(abs(x));
+        return x < 0 ? -floor(-x) : floor(x);;
     }
 
     template <typename valType>