docs: movement

doc/source/janim/anims/movement.rst

@@ -1,8 +1,75 @@
 movement
 ========
 
-.. automodule:: janim.anims.movement
-   :members:
-   :undoc-members:
-   :show-inheritance:
+.. autoclass:: janim.anims.movement.Homotopy
+    :show-inheritance:
 
+.. janim-example:: HomotopyExample
+    :media: ../../_static/videos/HomotopyExample.mp4
+
+    from janim.imports import *
+
+    class HomotopyExample(Timeline):
+        def construct(self):
+            def homotopy_func(x, y, z, t):
+                return [x * t, y * t, z]
+
+            square = Square()
+            self.play(Homotopy(square, homotopy_func))
+            self.forward(0.3)
+
+.. autoclass:: janim.anims.movement.ComplexHomotopy
+    :show-inheritance:
+
+.. janim-example:: ComplexHomotopyExample
+    :media: ../../_static/videos/ComplexHomotopyExample.mp4
+
+    from janim.imports import *
+
+    class ComplexHomotopyExample(Timeline):
+        def construct(self):
+            def complex_func(z: complex, t: float) -> complex:
+                return interpolate(z, z**3, t)
+
+            group = Group(
+                Text('Text'),
+                Square(side_length=1),
+            )
+            group.points.arrange(RIGHT, buff=2)
+
+            self.play(
+                *[ComplexHomotopy(
+                    item,
+                    complex_func
+                ) for item in group]
+            )
+            self.forward(0.3)
+
+.. autoclass:: janim.anims.movement.MoveAlongPath
+    :show-inheritance:
+
+.. janim-example:: MoveAlongPathExample
+    :media: ../../_static/videos/MoveAlongPathExample.mp4
+
+    from janim.imports import *
+
+    class MoveAlongPathExample(Timeline):
+        def construct(self) -> None:
+            line = Line(ORIGIN, RIGHT * Config.get.frame_width, buff=1)
+            dot1 = Dot(color=YELLOW)
+
+            curve = ParametricCurve(
+                lambda t: [math.cos(t) * t * 0.2, math.sin(t) * t * 0.2, 0],
+                (0, 10, 0.1)
+            )
+            dot2 = Dot(color=YELLOW)
+
+            group = Group(line, curve).show()
+            group.points.arrange(DOWN)
+
+            self.play(
+                MoveAlongPath(dot1, line),
+                MoveAlongPath(dot2, curve),
+                duration=2
+            )
+            self.forward(0.3)

janim/anims/movement.py

@@ -12,6 +12,11 @@
 
 
 class Homotopy(DataUpdater):
+    '''
+    一个从 (x, y, z, t) 到 (x’, y’, z’) 的函数
+
+    t 的取值范围是 [0, 1]，表示动画进度
+    '''
     def __init__(
         self,
         item: Item,
@@ -21,11 +26,6 @@ def __init__(
         root_only: bool = False,
         **kwargs
     ):
-        '''
-        一个从 (x, y, z, t) 到 (x’, y’, z’) 的函数
-
-        t 的取值范围是 [0, 1]，表示动画进度
-        '''
         self.homotopy = homotopy
         super().__init__(
             item,
@@ -47,15 +47,15 @@ def fn(point: np.ndarray) -> Vect:
 
 
 class ComplexHomotopy(Homotopy):
+    '''
+    与 Homotopy 类似，区别是用复数描述坐标
+    '''
     def __init__(
         self,
         item: Item,
         complex_homotopy: Callable[[complex, float], complex],
         **kwargs
     ):
-        '''
-        与 Homotopy 类似，区别是用复数描述坐标
-        '''
         def homotopy(x, y, z, t):
             c = complex_homotopy(complex(x, y), t)
             return (c.real, c.imag, z)