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Allow path_along_arc to take in multiple arc_angle values

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Grant Sanderson
2026-03-09 12:39:41 -05:00
parent 2c7209b13e
commit 2636e8dfef
2 changed files with 27 additions and 10 deletions
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4
manimlib/animation/transform.py
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@@ -28,7 +28,7 @@ class Transform(Animation):
self,
mobject: Mobject,
target_mobject: Mobject | None = None,
path_arc: float = 0.0,
path_arc: float | Tuple[float, float] = 0.0,
path_arc_axis: np.ndarray = OUT,
path_func: Callable | None = None,
**kwargs
@@ -43,7 +43,7 @@ class Transform(Animation):
def init_path_func(self) -> None:
if self.path_func is not None:
return
elif self.path_arc == 0:
elif isinstance(self.path_arc, float) and self.path_arc == 0:
self.path_func = straight_path
else:
self.path_func = path_along_arc(

33
manimlib/utils/paths.py
View File

@@ -34,26 +34,43 @@ def straight_path(
def path_along_arc(
arc_angle: float,
arc_angle: float | Tuple[float, float] | np.ndarray,
axis: Vect3 = OUT
) -> Callable[[Vect3Array, Vect3Array, float], Vect3Array]:
"""
arc_angle can be a single angle, or a pair of angles, in which case
the range of all angles between that pair will be used.
If vect is vector from start to end, [vect[:,1], -vect[:,0]] is
perpendicular to vect in the left direction.
"""
if abs(arc_angle) < STRAIGHT_PATH_THRESHOLD:
if isinstance(arc_angle, float | int) and abs(arc_angle) < STRAIGHT_PATH_THRESHOLD:
return straight_path
if get_norm(axis) == 0:
axis = OUT
unit_axis = axis / get_norm(axis)
def path(start_points, end_points, alpha):
vects = end_points - start_points
centers = start_points + 0.5 * vects
if arc_angle != np.pi:
centers += np.cross(unit_axis, vects / 2.0) / math.tan(arc_angle / 2)
rot_matrix_T = rotation_matrix_transpose(alpha * arc_angle, unit_axis)
return centers + np.dot(start_points - centers, rot_matrix_T)
if isinstance(arc_angle, float | int):
theta = arc_angle
else:
if isinstance(arc_angle, np.ndarray) and len(arc_angle) == len(start_points):
theta_range = arc_angle
else:
theta_range = np.linspace(arc_angle[0], arc_angle[-1], len(start_points))
# Avoid zero, mildly hacky
theta_range[np.abs(theta_range) < STRAIGHT_PATH_THRESHOLD] = STRAIGHT_PATH_THRESHOLD
# Get shape to match
theta = theta_range[:, np.newaxis] * np.ones(start_points.shape[1])
start_to_end = end_points - start_points
with np.errstate(divide='ignore', invalid='ignore'):
adjustments = np.nan_to_num(np.cross(unit_axis, start_to_end / 2.0) / np.tan(theta / 2))
arc_centers = start_points + 0.5 * start_to_end + adjustments
c_to_start = start_points - arc_centers
c_to_perp = np.cross(unit_axis, c_to_start)
return arc_centers + np.cos(alpha * theta) * c_to_start + np.sin(alpha * theta) * c_to_perp
return path