# HG changeset patch
# User Thibaut Girka <thib@sitedethib.com>
# Date 1314213165 -7200
# Node ID af7914413b8909590d43c88ed8e1925c696b3983
# Parent  4fe37a620b226ea77dd61cf65bbf188e03a675fa
Enable interpolators to use different formulas

diff --git a/pytouhou/utils/interpolator.py b/pytouhou/utils/interpolator.py
--- a/pytouhou/utils/interpolator.py
+++ b/pytouhou/utils/interpolator.py
@@ -14,17 +14,18 @@
 
 
 class Interpolator(object):
-    def __init__(self, values=()):
+    def __init__(self, values=(), formula=None):
         self.values = tuple(values)
         self.start_values = tuple(values)
         self.end_values = tuple(values)
         self.start_frame = 0
         self.end_frame = 0
         self._frame = 0
+        self._formula = formula or (lambda x: x)
 
 
     def __nonzero__(self):
-        return self._frame <= self.end_frame
+        return self._frame < self.end_frame
 
 
     def set_interpolation_start(self, frame, values):
@@ -47,12 +48,12 @@ class Interpolator(object):
 
     def update(self, frame):
         self._frame = frame
-        if frame >= self.end_frame:
+        if frame >= self.end_frame - 1:
             self.values = tuple(self.end_values)
             self.start_values = tuple(self.end_values)
             self.start_frame = frame
         else:
-            truc = float(frame - self.start_frame) / float(self.end_frame - self.start_frame)
-            self.values = tuple(start_value + truc * (end_value - start_value)
+            coeff = self._formula(float(frame - self.start_frame) / float(self.end_frame - self.start_frame))
+            self.values = tuple(start_value + coeff * (end_value - start_value)
                                 for (start_value, end_value) in zip(self.start_values, self.end_values))