3b1b-manim/manimlib/mobject/geometry.py

815 lines
25 KiB
Python

import itertools as it
import numpy as np
from manimlib.constants import *
from manimlib.mobject.mobject import Mobject
from manimlib.mobject.types.vectorized_mobject import VGroup
from manimlib.mobject.types.vectorized_mobject import VMobject
from manimlib.utils.bezier import interpolate
from manimlib.utils.config_ops import digest_config
from manimlib.utils.config_ops import digest_locals
from manimlib.utils.paths import path_along_arc
from manimlib.utils.space_ops import angle_of_vector
from manimlib.utils.space_ops import center_of_mass
from manimlib.utils.space_ops import compass_directions
from manimlib.utils.space_ops import get_norm
from manimlib.utils.space_ops import rotate_vector
class Arc(VMobject):
CONFIG = {
"radius": 1.0,
"start_angle": 0,
"num_anchors": 9,
"anchors_span_full_range": True,
"arc_center": ORIGIN,
}
def __init__(self, angle, **kwargs):
self.angle = angle
VMobject.__init__(self, **kwargs)
def generate_points(self):
anchors = np.array([
np.cos(a) * RIGHT + np.sin(a) * UP
for a in np.linspace(
self.start_angle,
self.start_angle + self.angle,
self.num_anchors
)
])
# Figure out which control points will give the
# Appropriate tangent lines to the circle
d_theta = self.angle / (self.num_anchors - 1.0)
tangent_vectors = np.zeros(anchors.shape)
tangent_vectors[:, 1] = anchors[:, 0]
tangent_vectors[:, 0] = -anchors[:, 1]
handles1 = anchors[:-1] + (d_theta / 3) * tangent_vectors[:-1]
handles2 = anchors[1:] - (d_theta / 3) * tangent_vectors[1:]
self.set_anchors_and_handles(
anchors, handles1, handles2
)
self.scale(self.radius, about_point=ORIGIN)
self.shift(self.arc_center)
def add_tip(self, tip_length=0.25, at_start=False, at_end=True):
# clear out any old tips
for submob in self.submobjects:
if submob.mark_paths_closed:
self.remove(submob)
# TODO, do this a better way
p1 = p2 = p3 = p4 = None
start_arrow = end_arrow = None
if at_end:
p1, p2 = self.points[-3:-1]
# self.points[-2:] did overshoot
start_arrow = Arrow(
p1, 2 * p2 - p1,
tip_length=tip_length,
max_tip_length_to_length_ratio=2.0
)
self.add(start_arrow.split()[-1]) # just the tip
if at_start:
p4, p3 = self.points[1:3]
# self.points[:2] did overshoot
end_arrow = Arrow(
p3, 2 * p4 - p3,
tip_length=tip_length,
max_tip_length_to_length_ratio=2.0
)
self.add(end_arrow.split()[-1])
self.set_color(self.get_color())
return self
def get_arc_center(self):
first_point = self.points[0]
radial_unit_vector = np.array(
[np.cos(self.start_angle), np.sin(self.start_angle), 0])
arc_center = first_point - self.radius * radial_unit_vector
return arc_center
def move_arc_center_to(self, point):
v = point - self.get_arc_center()
self.shift(v)
return self
def stop_angle(self):
return self.start_angle + self.angle
def set_bound_angles(self, start=0, stop=np.pi):
self.start_angle = start
self.angle = stop - start
return self
class ArcBetweenPoints(Arc):
def __init__(self, start_point, end_point, angle=TAU / 4, **kwargs):
if angle == 0:
raise Exception("Arc with zero curve angle: use Line instead.")
midpoint = 0.5 * (start_point + end_point)
distance_vector = end_point - start_point
normal_vector = np.array([-distance_vector[1], distance_vector[0], 0])
distance = get_norm(normal_vector)
normal_vector /= distance
if angle < 0:
normal_vector *= -1
radius = distance / 2 / np.sin(0.5 * np.abs(angle))
length = distance / 2 / np.tan(0.5 * np.abs(angle))
arc_center = midpoint + length * normal_vector
w = start_point - arc_center
if w[0] != 0:
start_angle = np.arctan2(w[1], w[0])
else:
start_angle = np.pi / 2
Arc.__init__(self, angle,
radius=radius,
start_angle=start_angle,
**kwargs)
self.move_arc_center_to(arc_center)
class CurvedArrow(ArcBetweenPoints):
def __init__(self, start_point, end_point, angle=TAU / 4, **kwargs):
# I know this is in reverse, but it works
if angle >= 0:
ArcBetweenPoints.__init__(
self, start_point, end_point, angle=angle, **kwargs)
self.add_tip(at_start=True, at_end=False)
else:
ArcBetweenPoints.__init__(
self, end_point, start_point, angle=-angle, **kwargs)
self.add_tip(at_start=False, at_end=True)
class CurvedDoubleArrow(ArcBetweenPoints):
def __init__(self, start_point, end_point, angle=TAU / 4, **kwargs):
ArcBetweenPoints.__init__(
self, start_point, end_point, angle=angle, **kwargs)
self.add_tip(at_start=True, at_end=True)
class Circle(Arc):
CONFIG = {
"color": RED,
"close_new_points": True,
"anchors_span_full_range": False
}
def __init__(self, **kwargs):
Arc.__init__(self, TAU, **kwargs)
def surround(self, mobject, dim_to_match=0, stretch=False, buffer_factor=1.2):
# Ignores dim_to_match and stretch; result will always be a circle
# TODO: Perhaps create an ellipse class to handle singele-dimension stretching
# Something goes wrong here when surrounding lines?
# TODO: Figure out and fix
self.replace(mobject, dim_to_match, stretch)
self.set_width(
np.sqrt(mobject.get_width()**2 + mobject.get_height()**2))
self.scale(buffer_factor)
def get_point_from_angle(self, angle):
start_angle = angle_of_vector(
self.points[0] - self.get_center()
)
return self.point_from_proportion(
(angle - start_angle) / TAU
)
class Dot(Circle):
CONFIG = {
"radius": 0.08,
"stroke_width": 0,
"fill_opacity": 1.0,
"color": WHITE
}
def __init__(self, point=ORIGIN, **kwargs):
Circle.__init__(self, **kwargs)
self.shift(point)
self.init_colors()
class Ellipse(VMobject):
CONFIG = {
"width": 2,
"height": 1
}
def generate_points(self):
circle = Circle(radius=1)
circle = circle.stretch_to_fit_width(self.width)
circle = circle.stretch_to_fit_height(self.height)
self.points = circle.points
class AnnularSector(VMobject):
CONFIG = {
"inner_radius": 1,
"outer_radius": 2,
"angle": TAU / 4,
"start_angle": 0,
"fill_opacity": 1,
"stroke_width": 0,
"color": WHITE,
"mark_paths_closed": True,
}
def generate_points(self):
arc1 = Arc(
angle=self.angle,
start_angle=self.start_angle,
radius=self.inner_radius,
)
arc2 = Arc(
angle=-1 * self.angle,
start_angle=self.start_angle + self.angle,
radius=self.outer_radius,
)
a1_to_a2_points = np.array([
interpolate(arc1.points[-1], arc2.points[0], alpha)
for alpha in np.linspace(0, 1, 4)
])
a2_to_a1_points = np.array([
interpolate(arc2.points[-1], arc1.points[0], alpha)
for alpha in np.linspace(0, 1, 4)
])
self.points = np.array(arc1.points)
self.add_control_points(a1_to_a2_points[1:])
self.add_control_points(arc2.points[1:])
self.add_control_points(a2_to_a1_points[1:])
def get_arc_center(self):
first_point = self.points[0]
last_point = self.points[-2]
v = last_point - first_point
radial_unit_vector = v / get_norm(v)
arc_center = first_point - self.inner_radius * radial_unit_vector
return arc_center
def move_arc_center_to(self, point):
v = point - self.get_arc_center()
self.shift(v)
return self
class Sector(AnnularSector):
CONFIG = {
"outer_radius": 1,
"inner_radius": 0
}
@property
def radius(self):
return self.outer_radius
@radius.setter
def radius(self, new_radius):
self.outer_radius = new_radius
class Annulus(Circle):
CONFIG = {
"inner_radius": 1,
"outer_radius": 2,
"fill_opacity": 1,
"stroke_width": 0,
"color": WHITE,
"mark_paths_closed": False,
"propagate_style_to_family": True
}
def generate_points(self):
self.points = []
self.radius = self.outer_radius
outer_circle = Circle(radius=self.outer_radius)
inner_circle = Circle(radius=self.inner_radius)
inner_circle.flip()
self.points = outer_circle.points
self.add_subpath(inner_circle.points)
class Line(VMobject):
CONFIG = {
"buff": 0,
"path_arc": None, # angle of arc specified here
"n_arc_anchors": 10, # Only used if path_arc is not None
}
def __init__(self, start, end, **kwargs):
digest_config(self, kwargs)
self.set_start_and_end(start, end)
VMobject.__init__(self, **kwargs)
def generate_points(self):
if self.path_arc is None:
self.set_points_as_corners([self.start, self.end])
else:
path_func = path_along_arc(self.path_arc)
self.set_points_smoothly([
path_func(self.start, self.end, alpha)
for alpha in np.linspace(0, 1, self.n_arc_anchors)
])
self.account_for_buff()
def set_path_arc(self, new_value):
self.path_arc = new_value
self.generate_points()
def account_for_buff(self):
length = self.get_arc_length()
if length < 2 * self.buff or self.buff == 0:
return
buff_proportion = self.buff / length
self.pointwise_become_partial(
self, buff_proportion, 1 - buff_proportion
)
def set_start_and_end(self, start, end):
start_to_end = self.pointify(end) - self.pointify(start)
vect = np.zeros(len(start_to_end))
longer_dim = np.argmax(list(map(abs, start_to_end)))
vect[longer_dim] = start_to_end[longer_dim]
self.start, self.end = [
arg.get_edge_center(unit * vect)
if isinstance(arg, Mobject)
else np.array(arg)
for arg, unit in zip([start, end], [1, -1])
]
def pointify(self, mob_or_point):
if isinstance(mob_or_point, Mobject):
return mob_or_point.get_center()
return np.array(mob_or_point)
def get_length(self):
start, end = self.get_start_and_end()
return get_norm(start - end)
def get_arc_length(self):
if self.path_arc:
anchors = self.get_anchors()
return sum([
get_norm(a2 - a1)
for a1, a2 in zip(anchors, anchors[1:])
])
else:
return self.get_length()
def get_start_and_end(self):
return self.get_start(), self.get_end()
def get_vector(self):
return self.get_end() - self.get_start()
def get_unit_vector(self):
vect = self.get_vector()
norm = get_norm(vect)
if norm == 0:
# TODO, is this the behavior I want?
return np.array(ORIGIN)
return vect / norm
def get_start(self):
return np.array(self.points[0])
def get_end(self):
return np.array(self.points[-1])
def get_slope(self):
start, end = self.get_start_and_end()
rise, run = [
float(end[i] - start[i])
for i in [1, 0]
]
return np.inf if run == 0 else rise / run
def get_angle(self):
start, end = self.get_start_and_end()
return angle_of_vector(end - start)
def set_angle(self, angle):
self.rotate(
angle - self.get_angle(),
about_point=self.get_start(),
)
def put_start_and_end_on(self, new_start, new_end):
self.start = new_start
self.end = new_end
self.buff = 0
self.generate_points()
return
def put_start_and_end_on_with_projection(self, new_start, new_end):
target_vect = np.array(new_end) - np.array(new_start)
curr_vect = self.get_vector()
curr_norm = get_norm(curr_vect)
if curr_norm == 0:
self.put_start_and_end_on(new_start, new_end)
return
target_norm = get_norm(target_vect)
if target_norm == 0:
epsilon = 0.001
self.scale(epsilon / curr_norm)
self.move_to(new_start)
return
unit_target = target_vect / target_norm
unit_curr = curr_vect / curr_norm
normal = np.cross(unit_target, unit_curr)
if get_norm(normal) == 0:
if unit_curr[0] == 0 and unit_curr[1] == 0:
normal = UP
else:
normal = OUT
angle_diff = np.arccos(
np.clip(np.dot(unit_target, unit_curr), -1, 1)
)
self.scale(target_norm / curr_norm)
self.rotate(-angle_diff, normal)
self.shift(new_start - self.get_start())
return self
class DashedLine(Line):
CONFIG = {
"dashed_segment_length": 0.05
}
def __init__(self, *args, **kwargs):
self.init_kwargs = kwargs
Line.__init__(self, *args, **kwargs)
def generate_points(self):
length = get_norm(self.end - self.start)
if length == 0:
self.add(Line(self.start, self.end))
return self
num_interp_points = int(length / self.dashed_segment_length)
# Even number ensures that start and end points are hit
if num_interp_points % 2 == 1:
num_interp_points += 1
points = [
interpolate(self.start, self.end, alpha)
for alpha in np.linspace(0, 1, num_interp_points)
]
includes = it.cycle([True, False])
self.submobjects = [
Line(p1, p2, **self.init_kwargs)
for p1, p2, include in zip(points, points[1:], includes)
if include
]
self.put_start_and_end_on_with_projection(self.start, self.end)
return self
def get_start(self):
if len(self.points) > 0:
return self[0].points[0]
else:
return self.start
def get_end(self):
if len(self) > 0:
return self[-1].points[-1]
else:
return self.end
class Elbow(VMobject):
CONFIG = {
"width": 0.2,
"angle": 0,
}
def __init__(self, **kwargs):
VMobject.__init__(self, **kwargs)
self.set_points_as_corners([UP, UP + RIGHT, RIGHT])
self.set_width(self.width, about_point=ORIGIN)
self.rotate(self.angle, about_point=ORIGIN)
class Arrow(Line):
CONFIG = {
"tip_length": 0.25,
"tip_width_to_length_ratio": 1,
"max_tip_length_to_length_ratio": 0.35,
"max_stem_width_to_tip_width_ratio": 0.3,
"buff": MED_SMALL_BUFF,
"propagate_style_to_family": False,
"preserve_tip_size_when_scaling": True,
"normal_vector": OUT,
"use_rectangular_stem": True,
"rectangular_stem_width": 0.05,
}
def __init__(self, *args, **kwargs):
points = list(map(self.pointify, args))
if len(args) == 1:
args = (points[0] + UP + LEFT, points[0])
Line.__init__(self, *args, **kwargs)
self.init_tip()
if self.use_rectangular_stem and not hasattr(self, "rect"):
self.add_rectangular_stem()
self.init_colors()
def init_tip(self):
self.add_tip()
def add_tip(self, add_at_end=True):
tip = VMobject(
close_new_points=True,
mark_paths_closed=True,
fill_color=self.color,
fill_opacity=1,
stroke_color=self.color,
stroke_width=0,
)
tip.add_at_end = add_at_end
self.set_tip_points(tip, add_at_end, preserve_normal=False)
self.add(tip)
if not hasattr(self, 'tip'):
self.tip = VGroup()
self.tip.match_style(tip)
self.tip.add(tip)
return tip
def add_rectangular_stem(self):
self.rect = Rectangle(
stroke_width=0,
fill_color=self.tip.get_fill_color(),
fill_opacity=self.tip.get_fill_opacity()
)
self.add_to_back(self.rect)
self.set_stroke(width=0)
self.set_rectangular_stem_points()
def set_rectangular_stem_points(self):
start, end = self.get_start_and_end()
tip_base_points = self.tip[0].get_anchors()[1:3]
tip_base = center_of_mass(tip_base_points)
tbp1, tbp2 = tip_base_points
perp_vect = tbp2 - tbp1
tip_base_width = get_norm(perp_vect)
if tip_base_width > 0:
perp_vect /= tip_base_width
width = min(
self.rectangular_stem_width,
self.max_stem_width_to_tip_width_ratio * tip_base_width,
)
if hasattr(self, "second_tip"):
start = center_of_mass(
self.second_tip.get_anchors()[1:]
)
self.rect.set_points_as_corners([
tip_base - perp_vect * width / 2,
start - perp_vect * width / 2,
start + perp_vect * width / 2,
tip_base + perp_vect * width / 2,
])
self.stem = self.rect # Alternate name
return self
def set_tip_points(
self, tip,
add_at_end=True,
tip_length=None,
preserve_normal=True,
):
if tip_length is None:
tip_length = self.tip_length
if preserve_normal:
normal_vector = self.get_normal_vector()
else:
normal_vector = self.normal_vector
line_length = get_norm(self.points[-1] - self.points[0])
tip_length = min(
tip_length, self.max_tip_length_to_length_ratio * line_length
)
indices = (-2, -1) if add_at_end else (1, 0)
pre_end_point, end_point = [
self.get_anchors()[index]
for index in indices
]
vect = end_point - pre_end_point
perp_vect = np.cross(vect, normal_vector)
for v in vect, perp_vect:
if get_norm(v) == 0:
v[0] = 1
v *= tip_length / get_norm(v)
ratio = self.tip_width_to_length_ratio
tip.set_points_as_corners([
end_point,
end_point - vect + perp_vect * ratio / 2,
end_point - vect - perp_vect * ratio / 2,
])
return self
def get_normal_vector(self):
p0, p1, p2 = self.tip[0].get_anchors()[:3]
result = np.cross(p2 - p1, p1 - p0)
norm = get_norm(result)
if norm == 0:
return self.normal_vector
else:
return result / norm
def reset_normal_vector(self):
self.normal_vector = self.get_normal_vector()
return self
def get_end(self):
if hasattr(self, "tip"):
return self.tip[0].get_anchors()[0]
else:
return Line.get_end(self)
def get_tip(self):
return self.tip
def put_start_and_end_on(self, *args, **kwargs):
Line.put_start_and_end_on(self, *args, **kwargs)
self.set_tip_points(self.tip[0], preserve_normal=False)
self.set_rectangular_stem_points()
return self
def scale(self, scale_factor, **kwargs):
Line.scale(self, scale_factor, **kwargs)
if self.preserve_tip_size_when_scaling:
for t in self.tip:
self.set_tip_points(t, add_at_end=t.add_at_end)
if self.use_rectangular_stem:
self.set_rectangular_stem_points()
return self
def copy(self):
return self.deepcopy()
class Vector(Arrow):
CONFIG = {
"color": YELLOW,
"buff": 0,
}
def __init__(self, direction, **kwargs):
if len(direction) == 2:
direction = np.append(np.array(direction), 0)
Arrow.__init__(self, ORIGIN, direction, **kwargs)
class DoubleArrow(Arrow):
def init_tip(self):
self.tip = VGroup()
for b in True, False:
t = self.add_tip(add_at_end=b)
t.add_at_end = b
self.tip.add(t)
self.tip.match_style(self.tip[0])
class CubicBezier(VMobject):
def __init__(self, points, **kwargs):
VMobject.__init__(self, **kwargs)
self.set_points(points)
class Polygon(VMobject):
CONFIG = {
"color": GREEN_D,
"mark_paths_closed": True,
"close_new_points": True,
}
def __init__(self, *vertices, **kwargs):
assert len(vertices) > 1
digest_locals(self)
VMobject.__init__(self, **kwargs)
def generate_points(self):
self.set_anchor_points(self.vertices, mode="corners")
def get_vertices(self):
return self.get_anchors_and_handles()[0]
class RegularPolygon(Polygon):
CONFIG = {
"start_angle": 0
}
def __init__(self, n=3, **kwargs):
digest_config(self, kwargs, locals())
start_vect = rotate_vector(RIGHT, self.start_angle)
vertices = compass_directions(n, start_vect)
Polygon.__init__(self, *vertices, **kwargs)
class Rectangle(VMobject):
CONFIG = {
"color": WHITE,
"height": 2.0,
"width": 4.0,
"mark_paths_closed": True,
"close_new_points": True,
}
def generate_points(self):
y, x = self.height / 2., self.width / 2.
self.set_anchor_points([
x * LEFT + y * UP,
x * RIGHT + y * UP,
x * RIGHT + y * DOWN,
x * LEFT + y * DOWN
], mode="corners")
class Square(Rectangle):
CONFIG = {
"side_length": 2.0,
}
def __init__(self, **kwargs):
digest_config(self, kwargs)
Rectangle.__init__(
self,
height=self.side_length,
width=self.side_length,
**kwargs
)
class RoundedRectangle(Rectangle):
CONFIG = {
"corner_radius": 0.5,
"close_new_points": True
}
def generate_points(self):
y, x = self.height / 2., self.width / 2.
r = self.corner_radius
arc_ul = ArcBetweenPoints(x * LEFT + (y - r) * UP, (x - r) * LEFT + y * UP, angle = -TAU/4)
arc_ur = ArcBetweenPoints((x - r) * RIGHT + y * UP, x * RIGHT + (y - r) * UP, angle = -TAU/4)
arc_lr = ArcBetweenPoints(x * RIGHT + (y - r) * DOWN, (x - r) * RIGHT + y * DOWN, angle = -TAU/4)
arc_ll = ArcBetweenPoints(x * LEFT + (y - r) * DOWN, (x - r) * LEFT + y * DOWN, angle = TAU/4) # sic! bug in ArcBetweenPoints?
points = arc_ul.points
points = np.append(points,np.array([y * UP]), axis = 0)
points = np.append(points,np.array([y * UP]), axis = 0)
points = np.append(points,arc_ur.points, axis = 0)
points = np.append(points,np.array([x * RIGHT]), axis = 0)
points = np.append(points,np.array([x * RIGHT]), axis = 0)
points = np.append(points,arc_lr.points, axis = 0)
points = np.append(points,np.array([y * DOWN]), axis = 0)
points = np.append(points,np.array([y * DOWN]), axis = 0)
points = np.append(points,arc_ll.points[::-1], axis = 0) # sic! see comment above
points = np.append(points,np.array([x * LEFT]), axis = 0)
points = np.append(points,np.array([x * LEFT]), axis = 0)
points = np.append(points,np.array([x * LEFT + (y - r) * UP]), axis = 0)
points = points[::-1]
self.set_points(points)
class Grid(VMobject):
CONFIG = {
"height": 6.0,
"width": 6.0,
}
def __init__(self, rows, columns, **kwargs):
digest_config(self, kwargs, locals())
VMobject.__init__(self, **kwargs)
def generate_points(self):
x_step = self.width / self.columns
y_step = self.height / self.rows
for x in np.arange(0, self.width + x_step, x_step):
self.add(Line(
[x - self.width / 2., -self.height / 2., 0],
[x - self.width / 2., self.height / 2., 0],
))
for y in np.arange(0, self.height + y_step, y_step):
self.add(Line(
[-self.width / 2., y - self.height / 2., 0],
[self.width / 2., y - self.height / 2., 0]
))