From 7b4f4380653de678e59626fa7dc4d92904ff2b5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Leclercq?= <lynix680@gmail.com>
Date: Fri, 14 Apr 2017 16:53:03 +0200
Subject: [PATCH] Math/Algorithm: Fix NumberEquals for signed integers

---
 include/Nazara/Math/Algorithm.inl | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/include/Nazara/Math/Algorithm.inl b/include/Nazara/Math/Algorithm.inl
index 9a0eaabfb..612cdf952 100644
--- a/include/Nazara/Math/Algorithm.inl
+++ b/include/Nazara/Math/Algorithm.inl
@@ -97,6 +97,29 @@ namespace Nz
 
 			return 0;
 		}
+
+		template<typename T> /*constexpr*/ std::enable_if_t<!std::is_signed<T>::value || !std::is_integral<T>::value, bool> NumberEquals(T a, T b, T maxDifference)
+		{
+			if (b > a)
+				std::swap(a, b);
+
+			T diff = a - b;
+			return diff <= maxDifference;
+		}
+
+		template<typename T> /*constexpr*/ std::enable_if_t<std::is_signed<T>::value && std::is_integral<T>::value, bool> NumberEquals(T a, T b, T maxDifference)
+		{
+			if (b > a)
+				std::swap(a, b);
+
+			if ((b < 0) && (a > std::numeric_limits<T>::max() + b))
+				return false;
+
+			if ((b > 0) && (a < std::numeric_limits<T>::min() + b))
+				return false;
+
+			return std::abs(a - b) <= maxDifference;
+		}
 	}
 
 	/*!
@@ -565,11 +588,7 @@ namespace Nz
 	//TODO: Mark as constexpr when supported by all major compilers
 	/*constexpr*/ inline bool NumberEquals(T a, T b, T maxDifference)
 	{
-		if (b > a)
-			std::swap(a, b);
-
-		T diff = a - b;
-		return diff <= maxDifference;
+		return Detail::NumberEquals(a, b, maxDifference);
 	}
 
 	/*!