From cb455f49ce08b412c323fec41829047aa6e228dc Mon Sep 17 00:00:00 2001
From: Christophe Riccio <g.truc.creation@gmail.com>
Date: Wed, 4 May 2011 10:32:44 +0100
Subject: [PATCH] Added GTX_ulp implementation of scalar functions (TODO:
 vector ones)

---
 glm/gtx/ulp.inl | 96 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 94 insertions(+), 2 deletions(-)

diff --git a/glm/gtx/ulp.inl b/glm/gtx/ulp.inl
index b99e8c49..dbd85a35 100644
--- a/glm/gtx/ulp.inl
+++ b/glm/gtx/ulp.inl
@@ -7,13 +7,105 @@
 // File    : glm/gtx/ulp.inl
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
-#include <cmath>
-#include <iostream>
+#if(GLM_COMPILER & GLM_COMPILER_VC)
+#	include <cfloat>
+#   define GLM_NEXT_AFTER _nextafterf
+#else
+#	include <cmath>
+#   define GLM_NEXT_AFTER nextafterf
+#endif
 
 namespace glm{
 namespace gtx{
 namespace ulp
 {
+    GLM_FUNC_QUALIFIER float next_float(float const & x)
+    {
+        return GLM_NEXT_AFTER(x, std::numeric_limits<float>::max());
+    }
+
+    GLM_FUNC_QUALIFIER double next_float(double const & x)
+    {
+        return GLM_NEXT_AFTER(x, std::numeric_limits<double>::max());
+    }
+
+    template<typename T, template<typename> class vecType>
+    GLM_FUNC_QUALIFIER vecType<T> next_float(vecType<T> const & x)
+    {
+        vecType<T> Result;
+        for(std::size_t i = 0; i < Result.length(); ++i)
+            Result[i] = next_float(x[i]);
+        return Result;
+    }
+
+    GLM_FUNC_QUALIFIER float prev_float(float const & x)
+    {
+        return GLM_NEXT_AFTER(x, std::numeric_limits<float>::min());
+    }
+
+    GLM_FUNC_QUALIFIER double prev_float(double const & x)
+    {
+        return GLM_NEXT_AFTER(x, std::numeric_limits<double>::min());
+    }
+
+    template<typename T, template<typename> class vecType>
+    GLM_FUNC_QUALIFIER vecType<T> prev_float(vecType<T> const & x)
+    {
+        vecType<T> Result;
+        for(std::size_t i = 0; i < Result.length(); ++i)
+            Result[i] = prev_float(x[i]);
+        return Result;
+    }
+
+    template <typename T>
+    GLM_FUNC_QUALIFIER T next_float(T const & x, std::size_t const & ulps)
+    {
+        T temp = x;
+        for(std::size_t i = 0; i < ulps; ++i)
+            temp = next_float(temp);
+        return temp;
+    }
+
+    template <typename T>
+    GLM_FUNC_QUALIFIER T prev_float(T const & x, std::size_t const & ulps)
+    {
+        T temp = x;
+        for(std::size_t i = 0; i < ulps; ++i)
+            temp = prev_float(temp);
+        return temp;
+    }
+
+    template <typename T>
+    GLM_FUNC_QUALIFIER std::size_t float_distance(T const & x, T const & y)
+    {
+        std::size_t ulp = 0;
+
+        if(x < y)
+        {
+            T temp = x;
+            while(temp != y && ulp < std::numeric_limits<std::size_t>::max())
+            {
+                ++ulp;
+                temp = next_float(temp);
+            }
+        }
+        else if(y < x)
+        {
+            T temp = y;
+            while(temp != x && ulp < std::numeric_limits<std::size_t>::max())
+            {
+                ++ulp;
+                temp = next_float(temp);
+            }
+        }
+        else // ==
+        {
+
+        }
+
+        return ulp;
+    }
+
 	inline std::size_t ulp
 	(
 		detail::thalf const & a,