From a53696a2dccf4219076a23b197abf2eee7274571 Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <Krajcevski@gmail.com>
Date: Fri, 13 Feb 2015 00:22:03 -0800
Subject: [PATCH 1/2] Specialize template for integer YCoCgR conversion to use
 bitshifts

---
 glm/gtx/color_space_YCoCg.inl | 90 +++++++++++++++++++++++++++--------
 1 file changed, 70 insertions(+), 20 deletions(-)

diff --git a/glm/gtx/color_space_YCoCg.inl b/glm/gtx/color_space_YCoCg.inl
index caf88221..273db475 100644
--- a/glm/gtx/color_space_YCoCg.inl
+++ b/glm/gtx/color_space_YCoCg.inl
@@ -45,19 +45,6 @@ namespace glm
 		return result;
 	}
 
-	template <typename T, precision P>
-	GLM_FUNC_QUALIFIER tvec3<T, P> rgb2YCoCgR
-	(
-		tvec3<T, P> const & rgbColor
-	)
-	{
-		tvec3<T, P> result;
-		result.x/*Y */ = rgbColor.g / T(2) + (rgbColor.r + rgbColor.b) / T(4);
-		result.y/*Co*/ = rgbColor.r - rgbColor.b;
-		result.z/*Cg*/ = rgbColor.g - (rgbColor.r + rgbColor.b) / T(2);
-		return result;
-	}
-
 	template <typename T, precision P>
 	GLM_FUNC_QUALIFIER tvec3<T, P> YCoCg2rgb
 	(
@@ -66,22 +53,85 @@ namespace glm
 	{
 		tvec3<T, P> result;
 		result.r = YCoCgColor.x + YCoCgColor.y - YCoCgColor.z;
-		result.g = YCoCgColor.x                + YCoCgColor.z;
+		result.g = YCoCgColor.x				   + YCoCgColor.z;
 		result.b = YCoCgColor.x - YCoCgColor.y - YCoCgColor.z;
 		return result;
 	}
 
+	template <typename T, precision P, bool isInteger>
+	class compute_YCoCgR {
+	public:
+		static GLM_FUNC_QUALIFIER tvec3<T, P> rgb2YCoCgR
+		(
+			tvec3<T, P> const & rgbColor
+		)
+		{
+			tvec3<T, P> result;
+			result.x/*Y */ = rgbColor.g / T(2) + (rgbColor.r + rgbColor.b) / T(4);
+			result.y/*Co*/ = rgbColor.r - rgbColor.b;
+			result.z/*Cg*/ = rgbColor.g - (rgbColor.r + rgbColor.b) / T(2);
+			return result;
+		}
+
+		static GLM_FUNC_QUALIFIER tvec3<T, P> YCoCgR2rgb
+		(
+			tvec3<T, P> const & YCoCgRColor
+		)
+		{
+			tvec3<T, P> result;
+			T tmp = YCoCgRColor.x - (YCoCgRColor.z / T(2));
+			result.g = YCoCgRColor.z + tmp;
+			result.b = tmp - (YCoCgRColor.y / T(2));
+			result.r = result.b + YCoCgRColor.y;
+			return result;
+		}
+	};
+#if 0
+	template <typename T, precision P>
+	class compute_YCoCgR<T, P, true> {
+	public:
+		static GLM_FUNC_QUALIFIER tvec3<T, P> rgb2YCoCgR
+		(
+			tvec3<T, P> const & rgbColor
+		)
+		{
+			tvec3<T, P> result;
+			result.y/*Co*/ = rgbColor.r - rgbColor.b;
+			T tmp = rgbColor.b + (result.y >> 1);
+			result.z/*Cg*/ = rgbColor.g - tmp;
+			result.x/*Y */ = tmp + (result.z >> 1);
+			return result;
+		}
+
+		static GLM_FUNC_QUALIFIER tvec3<T, P> YCoCgR2rgb
+		(
+			tvec3<T, P> const & YCoCgRColor
+		)
+		{
+			tvec3<T, P> result;
+			T tmp = YCoCgRColor.x - (YCoCgRColor.z >> 1);
+			result.g = YCoCgRColor.z + tmp;
+			result.b = tmp - (YCoCgRColor.y >> 1);
+			result.r = result.b + YCoCgRColor.y;
+			return result;
+		}
+	};
+#endif  
+	template <typename T, precision P>
+	GLM_FUNC_QUALIFIER tvec3<T, P> rgb2YCoCgR
+	(
+		tvec3<T, P> const & rgbColor
+	)
+	{
+		return compute_YCoCgR<T, P, std::numeric_limits<T>::is_integer>::rgb2YCoCgR(rgbColor);
+	}
+
 	template <typename T, precision P>
 	GLM_FUNC_QUALIFIER tvec3<T, P> YCoCgR2rgb
 	(
 		tvec3<T, P> const & YCoCgRColor
 	)
 	{
-		tvec3<T, P> result;
-		T tmp = YCoCgRColor.x - (YCoCgRColor.z / T(2));
-		result.g = YCoCgRColor.z + tmp;
-		result.b = tmp - (YCoCgRColor.y / T(2));
-		result.r = result.b + YCoCgRColor.y;
-		return result;
+		return compute_YCoCgR<T, P, std::numeric_limits<T>::is_integer>::YCoCgR2rgb(YCoCgRColor);
 	}
 }//namespace glm

From 2ba1ae95c2d152017e0a9dd27bb9b348c417f93b Mon Sep 17 00:00:00 2001
From: Pavel Krajcevski <Krajcevski@gmail.com>
Date: Fri, 13 Feb 2015 00:30:25 -0800
Subject: [PATCH 2/2] Remove testing #ifdefs

---
 glm/gtx/color_space_YCoCg.inl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/glm/gtx/color_space_YCoCg.inl b/glm/gtx/color_space_YCoCg.inl
index 273db475..45e41671 100644
--- a/glm/gtx/color_space_YCoCg.inl
+++ b/glm/gtx/color_space_YCoCg.inl
@@ -86,7 +86,7 @@ namespace glm
 			return result;
 		}
 	};
-#if 0
+
 	template <typename T, precision P>
 	class compute_YCoCgR<T, P, true> {
 	public:
@@ -116,7 +116,7 @@ namespace glm
 			return result;
 		}
 	};
-#endif  
+
 	template <typename T, precision P>
 	GLM_FUNC_QUALIFIER tvec3<T, P> rgb2YCoCgR
 	(