*slerp

1 files changed, 32 insertions, 6 deletions

diff --git a/src/libjin/math/je_math.h b/src/libjin/math/je_math.h
index f0a0a4c..4036696 100644
--- a/src/libjin/math/je_math.h
+++ b/src/libjin/math/je_math.h
@@ -59,12 +59,6 @@ namespace JinEngine
             return a > upper ? upper : a;
         }
     
-        template<typename T>
-        inline T lerp(T a, T b, float t)
-        {
-            return a + t * (b - a);
-        }
-
         inline float lerp(float a, float b, float f)
         {
             f = clamp<float>(f, 0, 1);
@@ -83,6 +77,38 @@ namespace JinEngine
             return -a;
         }
 
+        template<typename T>
+        inline T lerp(T a, T b, float t)
+        {
+            return a + t * (b - a);
+        }
+
+        template<typename T>
+        inline T slerp(T start, T end, float percent)
+        {
+            // Dot product - the cosine of the angle between 2 vectors.
+            float dot = start * end;
+            // Clamp it to be in the range of Acos()
+            // This may be unnecessary, but floating point
+            // precision can be a fickle mistress.
+            dot = clamp<float>(dot, -1.0f, 1.0f);
+            // Acos(dot) returns the angle between start and end,
+            // And multiplying that by percent returns the angle between
+            // start and the final result.
+            float theta = Mathf.Acos(dot)*percent;
+            Vector3 RelativeVec = end - start * dot;
+            RelativeVec.Normalize();
+            // Orthonormal basis
+            // The final result.
+            return ((start*Mathf.Cos(theta)) + (RelativeVec*Mathf.Sin(theta)));
+        }
+
+        template<typename T>
+        inline T nlerp(T a, T b, float t)
+        {
+
+        }
+
     } // namespace Math
 } // namespace JinEngine