Merge branch '0.9.1' of ssh://ogl-math.git.sourceforge.net/gitroot/ogl-math/ogl-math into 0.9.1

glm/gtc/matrix_transform.hpp

@@ -133,6 +133,14 @@ namespace glm
 			detail::tmat4x4<T> const & proj, 
 			detail::tvec4<U> const & viewport);
 
+		//! Define a picking region
+		//! From GLM_GTC_matrix_transform extension.
+		template <typename T, typename U> 
+		detail::tmat4x4<T> pickMatrix(
+			detail::tvec2<T> const & center, 
+			detail::tvec2<T> const & delta, 
+			detail::tvec4<U> const & viewport);
+
 		//! Build a look at view matrix.
 		//! From GLM_GTC_matrix_transform extension.
 		template <typename T> 

glm/gtc/matrix_transform.inl

@@ -324,6 +324,25 @@ namespace matrix_transform
 		return detail::tvec3<T>(obj);
 	}
 
+	template <typename T, typename U> 
+	detail::tmat4x4<T> pickMatrix
+	(
+		detail::tvec2<T> const & center, 
+		detail::tvec2<T> const & delta, 
+		detail::tvec4<U> const & viewport
+	)
+	{
+		assert(delta.x > 0.0f && delta.y > 0.0f)
+		detail::tmat4x4<T> Result(1.0f);
+
+		if(!(delta.x > 0.0f && delta.y > 0.0f)) 
+			return Result; // Error
+
+		// Translate and scale the picked region to the entire window
+		Result = translate(Result, (T(viewport[2]) - T(2) * (x - T(viewport[0]))) / delta.x, (T(viewport[3]) - T(2) * (y - T(viewport[1]))) / delta.y, T(0));
+		return scale(Result, T(viewport[2]) / delta.x, T(viewport[3]) / delta.y, T(1));
+	}
+
     template <typename T> 
     inline detail::tmat4x4<T> lookAt(
 		const detail::tvec3<T>& eye, 

glm/gtc/quaternion.hpp

@@ -150,7 +150,7 @@ namespace glm
 			detail::tquat<T> const & q1, 
 			detail::tquat<T> const & q2);
 		
-		//! Returns a LERP interpolated quaternion of x and y according a. 
+		//! Returns a SLERP interpolated quaternion of x and y according a. 
 		//! From GLM_GTC_quaternion extension.
 		template <typename T> 
 		detail::tquat<T> mix(

glm/gtc/quaternion.inl

@@ -370,6 +370,43 @@ namespace quaternion{
             k0 * x.z + k1 * y2.z);
     }
 
+    template <typename T>
+    inline detail::tquat<T> mix2
+	(
+		detail::tquat<T> const & x, 
+		detail::tquat<T> const & y, 
+		T const & a
+	)
+    {
+        bool flip = false;
+		if(a <= T(0)) return x;
+        if(a >= T(1)) return y;
+
+        T cos_t = dot(x, y);
+		if(cos_t < T(0))
+		{
+			cos_t = -cos_t;
+			flip = true;
+		}
+
+		T alpha(0), beta(0);
+
+		if(T(1) - cos_t < 1e-7)
+			beta = T(1) - alpha;
+		else
+		{
+			T theta = acos(cos_t);
+			T sin_t = sin(theta);
+			beta = sin(theta * (T(1) - alpha)) / sin_t;
+			alpha = sin(alpha * theta) / sin_t;
+		}
+
+		if(flip)
+			alpha = -alpha;
+		
+        return normalize(beta * x + alpha * y2);
+    }
+
     template <typename T> 
     inline detail::tquat<T> conjugate
 	(