From 56bd959f9e5ce37ff1578127eb64e9274031371d Mon Sep 17 00:00:00 2001
From: Janis Born <janis.born@rwth-aachen.de>
Date: Thu, 19 Dec 2013 16:16:28 +0100
Subject: [PATCH] fix vector angle functions possibly returning NaN

---
 glm/gtx/vector_angle.inl | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/glm/gtx/vector_angle.inl b/glm/gtx/vector_angle.inl
index 39e04f22..737e1cef 100644
--- a/glm/gtx/vector_angle.inl
+++ b/glm/gtx/vector_angle.inl
@@ -18,10 +18,12 @@ namespace glm
 	{
 		GLM_STATIC_ASSERT(std::numeric_limits<genType>::is_iec559, "'angle' only accept floating-point inputs");
 
+        genType Dot = clamp(dot(x, y), genType(0), genType(1));
+
 #ifdef GLM_FORCE_RADIANS
-		return acos(dot(x, y));
+        return acos(Dot);
 #else
-		return degrees(acos(dot(x, y)));
+        return degrees(acos(Dot));
 #endif
 	}
 
@@ -34,10 +36,12 @@ namespace glm
 	{
 		GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'angle' only accept floating-point inputs");
 
+        T Dot = clamp(dot(x, y), T(0), T(1));
+
 #ifdef GLM_FORCE_RADIANS
-		return acos(dot(x, y));
+        return acos(Dot);
 #else
-		return degrees(acos(dot(x, y)));
+        return degrees(acos(Dot));
 #endif
 	}
 
@@ -51,10 +55,12 @@ namespace glm
 	{
 		GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'orientedAngle' only accept floating-point inputs");
 
+        T Dot = clamp(dot(x, y), T(0), T(1));
+
 #ifdef GLM_FORCE_RADIANS
-		T const Angle(acos(dot(x, y)));
+        T const Angle(acos(Dot));
 #else
-		T const Angle(degrees(acos(dot(x, y))));
+        T const Angle(degrees(acos(Dot)));
 #endif
 		detail::tvec2<T, P> const TransformedVector(glm::rotate(x, Angle));
 		if(all(epsilonEqual(y, TransformedVector, T(0.01))))
@@ -73,10 +79,12 @@ namespace glm
 	{
 		GLM_STATIC_ASSERT(std::numeric_limits<T>::is_iec559, "'orientedAngle' only accept floating-point inputs");
 
+        T Dot = clamp(dot(x, y), T(0), T(1));
+
 #ifdef GLM_FORCE_RADIANS
-		T const Angle(acos(dot(x, y)));
+        T const Angle(acos(Dot));
 #else
-		T const Angle(degrees(acos(dot(x, y))));
+        T const Angle(degrees(acos(Dot)));
 #endif
 
 		if(dot(ref, cross(x, y)) < T(0))