move interpolation calculation to TInbetween

toonz/sources/common/tvrender/tinbetween.cpp

@@ -241,7 +241,8 @@ static void detectCorners(const TStroke *stroke, double minDegree,
       continue;
     }
 
-    if (j - 2 >= 0 && (corners.empty() || it == corners.begin() ||
+    if (j - 2 >= 0 &&
+        (corners.empty() || it == corners.begin() ||
          j - 1 != (*(it - 1)).first) &&
         j + 1 < (int)quadCount1 &&
         (corners.empty() || it == corners.end() || j + 1 != (*it).first)) {
@@ -1554,3 +1555,20 @@ void TInbetween::Imp::transferColor(const TVectorImageP &destination) const {
 TVectorImageP TInbetween::tween(double t) const { return m_imp->tween(t); }
 
 //-------------------------------------------------------------------
+
+double TInbetween::interpolation(double t, enum TweenAlgorithm algorithm) {
+  // in tutte le interpolazioni : s(0) = 0, s(1) = 1
+  switch (algorithm) {
+  case EaseInInterpolation:  // s'(1) = 0
+    return t * (2 - t);
+  case EaseOutInterpolation:  // s'(0) = 0
+    return t * t;
+  case EaseInOutInterpolation:  // s'(0) = s'(1) = 0
+    return t * t * (3 - 2 * t);
+  case LinearInterpolation:
+  default:
+    return t;
+  }
+}
+
+//-------------------------------------------------------------------

toonz/sources/include/tinbetween.h

@@ -24,6 +24,15 @@ class DVAPI TInbetween {
   std::unique_ptr<Imp> m_imp;
 
 public:
+  enum TweenAlgorithm {
+    LinearInterpolation,
+    EaseInInterpolation,
+    EaseOutInterpolation,
+    EaseInOutInterpolation
+  };
+
+  static double interpolation(double t, enum TweenAlgorithm);
+
   TInbetween(const TVectorImageP firstImage, const TVectorImageP lastImage);
 
   virtual ~TInbetween();

toonz/sources/toonz/filmstripcommand.cpp

@@ -2499,25 +2499,27 @@ void FilmstripCmd::inbetweenWithoutUndo(
   TVectorImageP img1 = sl->getFrame(fid1, false);
   if (!img0 || !img1) return;
 
+  enum TInbetween::TweenAlgorithm algorithm;
+  switch (interpolation) {
+  case II_Linear:
+    algorithm = TInbetween::LinearInterpolation;
+    break;
+  case II_EaseIn:
+    algorithm = TInbetween::EaseInInterpolation;
+    break;
+  case II_EaseOut:
+    algorithm = TInbetween::EaseOutInterpolation;
+    break;
+  case II_EaseInOut:
+    algorithm = TInbetween::EaseInOutInterpolation;
+    break;
+  }
+
   TInbetween inbetween(img0, img1);
   int i;
   for (i = ia + 1; i < ib; i++) {
     double t = (double)(i - ia) / (double)(ib - ia);
-    double s = t;
+    double s = TInbetween::interpolation(t, algorithm);
-    // in tutte le interpolazioni : s(0) = 0, s(1) = 1
-    switch (interpolation) {
-    case II_Linear:
-      break;
-    case II_EaseIn:
-      s = t * (2 - t);
-      break;  // s'(1) = 0
-    case II_EaseOut:
-      s = t * t;
-      break;  // s'(0) = 0
-    case II_EaseInOut:
-      s = t * t * (3 - 2 * t);
-      break;  // s'(0) = s'(1) = 0
-    }
 
     TVectorImageP vi = inbetween.tween(s);
     sl->setFrame(fids[i], vi);