new file mode 100644
--- /dev/null
+++ b/pytouhou/utils/interpolator.py
@@ -0,0 +1,36 @@
+class Interpolator(object):
+    def __init__(self, values=()):
+        self.values = tuple(values)
+        self.start_values = tuple(values)
+        self.end_values = tuple(values)
+        self.start_frame = 0
+        self.end_frame = 0
+
+
+    def set_interpolation_start(self, frame, values):
+        self.start_values = tuple(values)
+        self.start_frame = frame
+
+
+    def set_interpolation_end(self, frame, values):
+        self.end_values = tuple(values)
+        self.end_frame = frame
+
+
+    def set_interpolation_end_frame(self, end_frame):
+        self.end_frame = end_frame
+
+
+    def set_interpolation_end_values(self, values):
+        self.end_values = tuple(values)
+
+
+    def update(self, frame):
+        if frame >= self.end_frame:
+            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)
+                                for (start_value, end_value) in zip(self.start_values, self.end_values))