math: Move lerp function into SGMisc.

simgear/math/CMakeLists.txt

@@ -2,7 +2,6 @@ include (SimGearComponent)
 
 
 set(HEADERS 
-    Math.hxx
     SGBox.hxx
     SGCMath.hxx
     SGGeoc.hxx

simgear/math/Math.hxx

@@ -1,23 +0,0 @@
-#ifndef SIMGEAR_MATH_MATH_HXX
-#define SIMGEAR_MATH_MATH_HXX 1
-namespace simgear
-{
-namespace math
-{
-/** Linear interpolation between two values.
- */
-template<typename T>
-inline T lerp(const T& x, const T& y, double alpha)
-{
-    return x * (1.0 - alpha) + y * alpha;
-}
-
-template<typename T>
-inline T lerp(const T& x, const T& y, float alpha)
-{
-    return x * (1.0f - alpha) + y * alpha;
-}
-
-}
-}
-#endif

simgear/math/SGMisc.hxx

@@ -87,6 +87,11 @@ public:
   static int roundToInt(const T& v)
   { return int(round(v)); }
 
+  // Linear interpolation between two arbitrary typed values
+  template<typename S>
+  static S lerp(const S& val0, const S& val1, const T& t)
+  { return val0*(T(1) - t) + val1*t; }
+
 #ifndef NDEBUG
   /// Returns true if v is a NaN value
   /// Use with care: allways code that you do not need to use that!