EASINGS= ... partial(eased_lerp, ease=...)

src/keyframed/interpolation.py

@@ -3,6 +3,7 @@
 from typing import Callable
 import numpy as np
 import torch
+from functools import partial
 
 def bisect_left_keyframe(k: Number, curve:'Curve', *args, **kargs) -> 'Keyframe':
     """
@@ -90,8 +91,11 @@ def exp_decay(t, curve, decay_rate):
     return v0 * math.exp(-td * decay_rate)
 
 def sine_wave(t, curve, wavelength=None, frequency=None, phase=0, amplitude=1):
-    if (wavelength is None) and (frequency is not None):
-        wavelength = 1/frequency
+    if (wavelength is None): 
+        if (frequency is not None):
+            wavelength = 1/frequency
+        else:
+            wavelength = 4 # interpolate from 0 to pi/2
     return amplitude * math.sin(2*math.pi*t / wavelength + phase)
 
 INTERPOLATORS={
@@ -104,6 +108,17 @@ def sine_wave(t, curve, wavelength=None, frequency=None, phase=0, amplitude=1):
     'sine_wave':sine_wave,
 }
 
+EASINGS={
+    None:bisect_left_value,
+    'previous':bisect_left_value,
+    'next':bisect_right_value,
+    'linear':partial(eased_lerp, ease=lambda t: t),
+    'sin':partial(eased_lerp, ease=lambda t: math.sin(t * math.pi / 2)),
+    'sin^2':partial(eased_lerp, ease=lambda t: math.sin(t * math.pi / 2)**2),
+
+}
+
+
 def register_interpolation_method(name:str, f:Callable):
     """
     Adds a new interpolation method to the INTERPOLATORS registry.

tests/test_interpolation.py

@@ -1,11 +1,12 @@
 import pytest
+import math
 
 from keyframed import Curve, Keyframe
-
 from keyframed.interpolation import (
     register_interpolation_method, 
     bisect_left_value, 
-    INTERPOLATORS
+    INTERPOLATORS,
+    EASINGS
 )
 
 
@@ -117,4 +118,16 @@ def test_curve_w_kf_specified_interpolator():
     c1 = Curve({0:1, 5:Keyframe(t=5,value=1,interpolation_method='linear'), 9:5})
     assert c1[7] == 3
 
-###############
+###############
+
+def test_sin():
+    c1 = Curve({0:0, 2:1}, default_interpolation=EASINGS['sin'])
+    assert c1[1] == math.sin(math.pi/4)
+
+def test_sin():
+    c1 = Curve({0:0, 2:2}, default_interpolation=EASINGS['sin'])
+    assert c1[1] == 2*math.sin(math.pi/4)
+
+def test_sin2():
+    c1 = Curve({0:0, 2:1}, default_interpolation=EASINGS['sin^2'])
+    assert c1[1] == math.sin(math.pi/4)**2