From 28fbcebf98b627b4cfb46e317ca89f983c07778c Mon Sep 17 00:00:00 2001
From: Dander7BD <dander.1981@gmail.com>
Date: Mon, 20 Jan 2014 18:45:34 +0100
Subject: [PATCH] general lerp & vector nlerp

---
 Code/OysterMath/LinearMath.h | 79 ++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/Code/OysterMath/LinearMath.h b/Code/OysterMath/LinearMath.h
index b5eab471..791999db 100644
--- a/Code/OysterMath/LinearMath.h
+++ b/Code/OysterMath/LinearMath.h
@@ -146,6 +146,85 @@ namespace LinearAlgebra
 		targetMem = out * (in.GetAdjoint() /= d);
 		return true;
 	}
+
+	/********************************************************************
+	 * Linear Interpolation
+	 * @return start * (1-t) + end * t
+	 ********************************************************************/
+	template<typename PointType, typename ScalarType>
+	inline PointType Lerp( const PointType &start, const PointType &end,  const ScalarType &t )
+	{
+		return end * t + start * ( 1 - t );
+	}
+
+	/********************************************************************
+	 * Normalized Linear Interpolation
+	 * @return nullvector if impossible to solve.
+	 ********************************************************************/
+	template<typename ScalarType>
+	inline Vector2<ScalarType> Nlerp( const Vector2<ScalarType> &start, const Vector2<ScalarType> &end,  const ScalarType &t )
+	{
+		Vector2<ScalarType> output = Lerp( start, end, t );
+		ScalarType magnitudeSquared = output.Dot( output );
+		if( magnitudeSquared == 0 )
+		{
+			ScalarType half = t * 0.5f;
+			output = Lerp( start, end, half );
+			magnitudeSquared = output.Dot( output );
+
+			if( magnitudeSquared == 0 )
+				return output; // error: returning nullvector
+
+			return Nlerp( output /= magnitudeSquared, end, half / (1.0f - half) );
+		}
+		return output /= magnitudeSquared;
+	}
+
+	/********************************************************************
+	 * Normalized Linear Interpolation
+	 * @return nullvector if impossible to solve.
+	 ********************************************************************/
+	template<typename ScalarType>
+	inline Vector3<ScalarType> Nlerp( const Vector3<ScalarType> &start, const Vector3<ScalarType> &end,  const ScalarType &t )
+	{
+		Vector3<ScalarType> output = Lerp( start, end, t );
+		ScalarType magnitudeSquared = output.Dot( output );
+		if( magnitudeSquared == 0 )
+		{
+			ScalarType half = t * 0.5f;
+			output = Lerp( start, end, half );
+			magnitudeSquared = output.Dot( output );
+
+			if( magnitudeSquared == 0 )
+				return output; // error: returning nullvector
+
+			return Nlerp( output /= magnitudeSquared, end, half / (1.0f - half) );
+		}
+		return output /= magnitudeSquared;
+	}
+
+	/********************************************************************
+	 * Normalized Linear Interpolation
+	 * @return nullvector if impossible to solve.
+	 ********************************************************************/
+	template<typename ScalarType>
+	inline Vector4<ScalarType> Nlerp( const Vector4<ScalarType> &start, const Vector4<ScalarType> &end,  const ScalarType &t )
+	{
+		Vector4<ScalarType> output = Lerp( start, end, t );
+		ScalarType magnitudeSquared = output.Dot( output );
+		if( magnitudeSquared == 0 )
+		{
+			ScalarType half = t * 0.5f;
+			output = Lerp( start, end, half );
+			magnitudeSquared = output.Dot( output );
+
+			if( magnitudeSquared == 0 )
+				return output; // error: returning nullvector
+
+			return Nlerp( output /= magnitudeSquared, end, half / (1.0f - half) );
+		}
+		return output /= magnitudeSquared;
+	}
 }
 
 namespace LinearAlgebra2D