Added log2 to GTC_integer

glm/gtc/integer.hpp

@@ -41,8 +41,8 @@
 // Dependencies
 #include "../detail/setup.hpp"
 #include "../detail/precision.hpp"
-#include "../detail/type_int.hpp"
-#include "../detail/_vectorize.hpp"
+#include "../detail/func_integer.hpp"
+#include "../detail/func_exponential.hpp"
 #include <limits>
 
 #if(defined(GLM_MESSAGES) && !defined(GLM_EXT_INCLUDED))
@@ -54,7 +54,10 @@ namespace glm
 	/// @addtogroup gtc_integer
 	/// @{
 
-
+	/// Returns the log2 of x. Can be reliably using to compute mipmap count from the texture size.
+	/// From GLM_GTC_integer extension.
+	template <typename genIUType>
+	GLM_FUNC_DECL genIUType log2(genIUType x);
 
 	/// @}
 } //namespace glm

glm/gtc/integer.inl

@@ -29,9 +29,19 @@
 namespace glm{
 namespace detail
 {
+	GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x) 
+	{
+		return 31u - findMSB(x);
+	}
 
+	template <>
+	struct compute_log2<false>
+	{
+		template <typename T>
+		GLM_FUNC_QUALIFIER T operator() (T const & Value) const
+		{
+			return Value <= static_cast<T>(1) ? T(0) : T(32) - nlz(Value - T(1));
+		}
+	};
 }//namespace detail
-
-
-
 }//namespace glm