JAnim Documentation¶
JAnim is a library for creating smooth animations, built around the core concept of programmatic animation. It supports real-time editing, live preview, and a wide range of additional powerful features.
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Below are some example showcases (Note: you can click on the tab titles to quickly collapse this section)
HelloJAnimExample ¶
from janim.imports import *
class HelloJAnimExample(Timeline):
def construct(self):
# define items
circle = Circle(color=BLUE)
square = Square(color=GREEN, fill_alpha=0.5)
# do animations
self.forward()
self.play(Create(circle))
self.play(Transform(circle, square))
self.play(Uncreate(square))
self.forward()
BasicAnimationExample ¶
from janim.imports import *
class BasicAnimationExample(Timeline):
def construct(self):
circle = Circle()
star = Star()
self.forward()
self.play(Create(circle))
self.play(circle.anim.points.shift(LEFT * 3).scale(1.5))
self.play(circle.anim.set(color=RED, fill_alpha=0.5))
self.play(SpinInFromNothing(star))
self.play(star.anim.points.shift(RIGHT * 3).scale(1.5))
self.play(star.anim.set(color=YELLOW, fill_alpha=0.5))
self.forward()
See also:
TextExample ¶
from janim.imports import *
class TextExample(Timeline):
def construct(self):
txt = Text('Here is some text', font_size=64)
desc = Group(
Text('You can also apply <c BLUE>styles</c> to the text.', format=Text.Format.RichText),
Text('You can also apply <c GREEN><fs 1.4>styles</fs></c> to the text.', format=Text.Format.RichText),
)
group = Group(txt, desc)
group.points.arrange(DOWN, buff=MED_LARGE_BUFF)
self.forward()
self.play(Write(txt))
self.play(FadeIn(desc[0], UP))
self.play(Transform(desc[0], desc[1]))
self.forward()
TypstExample ¶
from janim.imports import *
typst_doc = t_(
R'''
JAnim provides `TypstText` and `TypstMath` classes to insert Typst content.
Math expressions are also supported.
$ A = pi r^2 $
$ "area" = pi dot "radius"^2 $
$ cal(A) :=
{ x in RR | x "is natural" } $
#let x = 5
$ #x < 17 $
You can also use `TypstDoc`, which automatically align to the top of the viewport,
instead of the center.
''')
class TypstExample(Timeline):
CONFIG = Config(
typst_shared_preamble=t_(
R'''
#import "@janim/colors:0.0.0": *
#show raw: set text(BLUE)
''')
)
def construct(self):
doc = TypstDoc(typst_doc)
group = Group(
Text('TypstText', color=BLUE),
TypstText('This is a sentence with a math expression $f(x)=x^2$'),
Text('TypstMath', color=BLUE),
TypstMath('sum_(i=1)^n x_i = x_1 + x_2 + dots.c + x_n')
)
group.points.arrange_in_grid()
# The rendering speed of animations applied to text is relatively slow
self.play(Write(doc), duration=4)
self.forward()
self.play(FadeOut(doc))
self.play(Write(group))
self.forward()
self.play(FadeOut(group))
See also:
TypstColorizeExample ¶
from janim.imports import *
class TypstColorizeExample(Timeline):
def construct(self):
typ = TypstMath('cos^2 theta + sin^2 theta = 1', scale=3).show()
self.forward()
self.play(typ['cos'].anim.set(color=BLUE))
self.play(typ['sin'].anim.set(color=BLUE))
self.play(typ['theta', 0].anim.set(color=GOLD))
self.play(typ['theta', 1].anim.set(color=ORANGE))
self.forward()
self.play(typ['theta', ...].anim.set(color=GREEN))
self.play(typ['space^2', ...].anim.set(color=RED))
self.forward()
See also:
AnimatingPiExample ¶
from janim.imports import *
class AnimatingPiExample(Timeline):
def construct(self):
grid = TypstMath('pi') * 100
grid.points.scale(2).arrange_in_grid(10, 10, buff=0.2)
grid.show()
self.play(grid.anim.points.shift(LEFT))
self.play(grid(VItem).anim.color.set(YELLOW))
self.forward()
self.play(grid(VItem).anim.color.set(BLUE))
self.forward()
self.play(grid.anim.points.to_center().set_height(TAU - MED_SMALL_BUFF))
self.forward()
self.play(grid.anim.points.apply_complex_fn(np.exp), duration=5)
self.forward()
self.play(
grid.anim.points.apply_point_fn(
lambda p: [
p[0] + 0.5 * math.sin(p[1]),
p[1] + 0.5 * math.sin(p[0]),
p[2]
]
),
duration=5
)
self.forward()
NumberPlaneExample ¶
from janim.imports import *
class NumberPlaneExample(Timeline):
def construct(self):
plane = NumberPlane(faded_line_ratio=1)
sin_graph = plane.get_graph(lambda x: math.sin(x))
self.forward(0.2)
self.play(Write(plane, lag_ratio=0.05))
self.play(Write(sin_graph))
self.forward()
self.play(
plane.anim.points.apply_matrix([
[3, -1],
[1, 2]
]),
sin_graph.anim(),
duration=2
)
self.forward()
See also:
UpdaterExample ¶
from janim.imports import *
class UpdaterExample(Timeline):
def construct(self):
square = Square(fill_color=BLUE_E, fill_alpha=1).show()
brace = Brace(square, UP).show()
def text_updater(p: UpdaterParams):
cmpt = brace.current().points
return cmpt.create_text(f'Width = {cmpt.brace_length:.2f}')
self.prepare(
DataUpdater(
brace,
lambda data, p: data.points.match(square.current())
),
ItemUpdater(None, text_updater),
duration=10
)
self.forward()
self.play(square.anim.points.scale(2))
self.play(square.anim.points.scale(0.5))
self.play(square.anim.points.set_width(5, stretch=True))
w0 = square.points.box.width
self.play(
DataUpdater(
square,
lambda data, p: data.points.set_width(
w0 + 0.5 * w0 * math.sin(p.alpha * p.range.duration)
)
),
duration=5
)
self.forward()
See also:
ArrowPointingExample ¶
from janim.imports import *
class ArrowPointingExample(Timeline):
def construct(self):
dot1 = Dot(LEFT * 3)
dot2 = Dot()
arrow = Arrow(dot1, dot2, color=YELLOW)
self.show(dot1, dot2, arrow)
self.play(
dot2.update.points.rotate(TAU, about_point=RIGHT * 2),
GroupUpdater(
arrow,
lambda data, p:
data.set_start_and_end(
dot1.points.box.center,
dot2.current().points.box.center
)
),
duration=4
)
See also:
CombineUpdatersExample ¶
from janim.imports import *
class CombineUpdatersExample(Timeline):
def construct(self):
square = Square()
square.points.to_border(LEFT)
# Here, a new Updater is accumulated for every `play`
# to show the effect of animation combination
self.play(
square.anim.points.to_border(RIGHT),
duration=2
)
###############################
square.points.to_border(LEFT)
self.play(
square.anim.points.to_border(RIGHT),
DataUpdater(
square,
lambda data, p: data.points.shift(UP * math.sin(p.alpha * 4 * PI)),
become_at_end=False
),
duration=2
)
###############################
square.points.to_border(LEFT)
self.play(
square.anim.points.to_border(RIGHT),
DataUpdater(
square,
lambda data, p: data.points.shift(UP * math.sin(p.alpha * 4 * PI)),
become_at_end=False
),
square.update(become_at_end=False).color.set(BLUE).r.points.rotate(-TAU),
duration=2
)
See also:
RotatingPieExample ¶
from janim.imports import *
class RotatingPieExample(Timeline):
def construct(self):
pie = Group(*[
Sector(start_angle=i * TAU / 4, angle=TAU / 4, radius=1.5, color=color, fill_alpha=1, stroke_alpha=0)
.points.shift(rotate_vector(UR * 0.05, i * TAU / 4))
.r
for i, color in enumerate([RED, PURPLE, MAROON, GOLD])
])
self.play(
GroupUpdater(
pie,
lambda data, p: data.points.rotate(p.alpha * TAU, about_point=ORIGIN),
duration=5
),
DataUpdater(
pie[0],
lambda data, p: data.points.shift(normalize(data.mark.get()) * p.alpha),
rate_func=there_and_back,
become_at_end=False,
at=2,
duration=2
)
)
See also:
MarkedItemExample ¶
from janim.imports import *
class MarkedSquare(MarkedItem, Square):
def __init__(self, side_length: float = 2.0, **kwargs):
super().__init__(side_length, **kwargs)
self.mark.set_points([RIGHT * side_length / 4, DOWN * side_length / 4])
class MarkedItemExample(Timeline):
def construct(self):
square = MarkedSquare()
tri1 = Triangle(radius=0.2, color=GREEN)
tri2 = Triangle(radius=0.2, color=BLUE)
dots = DotCloud(color=RED)
self.play(
square.update.points.rotate(TAU),
DataUpdater(
square,
lambda data, p: data.points.shift(RIGHT * math.sin(4 * math.pi * p.alpha))
),
DataUpdater(
tri1,
lambda data, p: data.mark.set(square.current().mark.get())
),
DataUpdater(
tri2,
lambda data, p: data.mark.set(square.current().mark.get(index=1))
),
DataUpdater(
dots,
lambda data, p: data.points.set(square.current().mark.get_points()),
skip_null_items=False
),
duration=4
)
See also:
FrameEffectExample ¶
from janim.imports import *
class FrameEffectExample(Timeline):
def construct(self):
squares = Square(0.5, color=BLUE, fill_alpha=0.3) * 49
squares.points.arrange_in_grid()
effect1 = SimpleFrameEffect( # (2~8s) Squares at [::2] produce a color gradient
squares[::2],
shader='''
f_color = frame_texture(v_texcoord);
f_color.gb *= v_texcoord;
'''
)
effect2 = SimpleFrameEffect( # (4~8s) Squares at [1::2] produce a glitch effect
squares[1::2],
shader='''
vec2 uv = v_texcoord;
float glitchStrength = sin(time) * 0.02;
vec2 offset = vec2(glitchStrength, 0.0);
float r = frame_texture(uv + offset).r;
float g = frame_texture(uv).g;
float b = frame_texture(uv - offset).b;
float a = max(frame_texture(uv + offset).a, max(frame_texture(uv).a, frame_texture(uv - offset).a));
float lineNoise = step(0.5, fract(uv.y * 10.0 + time));
r *= lineNoise;
b *= lineNoise;
f_color = vec4(r, g, b, a);
''',
uniforms=['float time']
)
self.schedule(2, effect1.show)
self.play(
Rotate(squares, TAU, duration=8),
DataUpdater(
effect2,
lambda data, p: data.apply_uniforms(time=p.elapsed),
at=4,
duration=4
)
)
See also:
ThreeDShapesExample ¶
from janim.imports import *
class _ThreeDShapesExampleSub(Timeline):
def __init__(self, shape_type: str, background_color: JAnimColor):
super().__init__()
self.shape_type = shape_type
self.background_color = background_color
def construct(self):
if self.shape_type == 'smooth':
axes = ThreeDAxes((-8, 8), (-8, 8), (-8, 8)).apply_depth_test()
self.prepare(FadeIn(axes, at=1))
background = FrameRect(fill_alpha=1, fill_color=self.background_color, stroke_alpha=0, depth=100)
background.fix_in_frame()
self.prepare(FadeIn(background, at=1.5, duration=3))
for shape in [Torus(2, 1), Cylinder(2, 4), Cone(2, 4)]:
item = shape.into(self.shape_type).show()
self.play(self.RotatingCamera(), duration=4)
item.hide()
def RotatingCamera(self):
return AnimGroup(
DataUpdater(
self.camera,
lambda data, p: data.points.rotate(TAU * p.alpha, axis=RIGHT),
rate_func=linear
),
DataUpdater(
self.camera,
lambda data, p: data.points.rotate(TAU * p.alpha, axis=OUT),
rate_func=linear
),
)
class ThreeDShapesExample(Timeline):
def construct(self):
subs = [
_ThreeDShapesExampleSub(type, color).build().to_item()
for type, color in zip(
['checker', 'wire', 'smooth', 'dots'],
['#000022', '#000033', '#000033', '#000022']
)
]
subs[0].show()
effects = [
RectClip(sub, anchor=ORIGIN)
for sub in subs
]
effects[0].show().depth.set(-1)
dirs = [UL, UR, DL, DR]
self.forward()
for sub, effect, dir in zip(subs, effects, dirs):
self.show(sub, effect)
self.prepare(
effect.anim
.points.scale(0.5).to_border(dir, buff=0)
.r.transform.set(scale=0.5)
)
self.forward_to(subs[0].duration)
MaskExample ¶
from janim.imports import *
class MaskExample(Timeline):
def construct(self):
## Part 1: Text floating up animation in a rectangular mask
txt = Text("Mask Example!")
txt.points.scale(2).move_to(DOWN * 0.5)
# Create a rectangular mask positioned above the text
mask1_shape = Rect(txt.points.box.width, txt.points.box.height)
mask1_shape.points.next_to(txt, UP, buff=0.5)
mask1 = ShapeMask(txt, shape=mask1_shape).show()
# Text gradually floating upward
self.play(
*[
char.anim.points.shift(UP * (0.5 + txt.points.box.height))
for char in txt[0]
],
lag_ratio=0.1,
)
self.forward()
## Part 2: Mask and text transformation
# Transform the mask to a circle
mask2 = ShapeMask(txt, shape=Circle())
self.play(Transform(mask1, mask2))
self.forward()
# Mask feathering
rect = Rect(3, 3, color=LIGHT_BROWN, fill_alpha=1, depth=10)
self.play(FadeIn(rect))
self.play(
mask2.anim.points.shift(UP * 0.5)
.r.feather.set(0.1),
)
self.play(
Succession(
txt.anim.points.shift(LEFT * 1),
txt.anim.points.shift(RIGHT * 1),
)
)
self.forward()
# Transform while holding the item
txt2 = Text("The mask should be hold")
txt2.points.scale(2)
mask2.apply(txt2)
self.play(TransformMatchingDiff(txt, txt2))
self.forward()
# Fade out of the mask itself
self.play(
FadeOut(rect),
FadeOut(mask2),
)
self.forward()
self.play(FadeOut(txt2))
self.forward()
## Part 3: Mask with boolean operations
dot1 = Dot(LEFT, 1.5, color=YELLOW, fill_alpha=0.25).show()
dot2 = Dot(RIGHT, 1.5, color=YELLOW, fill_alpha=0.25).show()
txt3 = Text('Some Example Text Here', font_size=40).show()
# Create mask union and intersection using boolean_ops
mask_union = ShapeMask(
txt3,
shape=boolean_ops.Union(dot1, dot2)
)
mask_intersection = ShapeMask(
txt3,
shape=boolean_ops.Intersection(dot1, dot2)
)
self.forward()
self.play(FadeIn(mask_union))
self.forward(0.5)
self.play(Transform(mask_union, mask_intersection), duration=0.5)
self.forward(0.5)
self.play(Transform(mask_intersection, mask_union), duration=0.5)
self.forward(0.5)
self.play(FadeOut(Group(dot1, dot2, txt3)))
self.forward()
## Part 4: Complex shape mask with special effects
# Complex shape mask
txt_fashion = Text('Fashion')
txt_fashion.points.scale(10)
dots = DotCloud(
*[
[i * 0.3 + 0.15, j * 0.3, 0]
for j in range(20, -40, -1)
for i in range(-23, 23)
],
radius=0.1,
color=PURPLE_E,
)
mask3 = ShapeMask(dots, shape=txt_fashion).show()
self.prepare(
dots.anim(rate_func=linear).points.shift(UP * 3),
duration=5.0,
)
self.play(FadeIn(dots))
self.forward(1.5)
self.play(mask3.anim.invert.set(1.0))
self.forward(1.5)
See also:
BallsCollisionExample ¶
from janim.imports import *
class Ball(Dot):
speed = CustomData()
def __init__(self, radius: float):
super().__init__(radius=radius, color=BLUE)
self.speed.set(ORIGIN)
class BallsCollisionExample(Timeline):
def construct(self):
# Configuration
left = -4
right = 4
bottom = -3
top = 3
radius = 0.25
ball_count = 25
# Container boundary
Polygon([left, top, 0], [left, bottom, 0], [right, bottom, 0], [right, top, 0], fill_alpha=0.2).show()
# Balls inside the container
balls = Ball(radius) * ball_count
# Generate non-overlapping initial positions
positions = []
rng = np.random.default_rng(1234)
for ball in balls:
# Initial position
while True:
pos = np.array([
rng.uniform(left + radius, right - radius),
rng.uniform(bottom + radius, top - radius),
0,
])
if all(np.linalg.norm(pos - other) >= 2 * radius for other in positions):
break
ball.points.move_to(pos)
positions.append(pos)
# Initial velocity
ball.speed.set(
np.array([
rng.uniform(-3, 3),
rng.uniform(-3, 3),
0,
])
)
def updater(group: Group[Ball], p) -> None:
dt = p.dt
# 1. Move according to velocity
for ball in group:
ball.points.shift(ball.speed.get() * dt)
# 2. Collision with container boundaries
for ball in group:
pos = ball.points.box.center
speed = ball.speed.get().copy()
if pos[0] - radius < left:
ball.points.set_x(left + radius)
speed[0] = abs(speed[0])
elif pos[0] + radius > right:
ball.points.set_x(right - radius)
speed[0] = -abs(speed[0])
if pos[1] - radius < bottom:
ball.points.set_y(bottom + radius)
speed[1] = abs(speed[1])
elif pos[1] + radius > top:
ball.points.set_y(top - radius)
speed[1] = -abs(speed[1])
ball.speed.set(speed)
# 3. Perfectly elastic collisions between balls
for i in range(len(group)):
for j in range(i + 1, len(group)):
ball1 = group[i]
ball2 = group[j]
p1 = ball1.points.box.center
p2 = ball2.points.box.center
delta = p2 - p1
dist = np.linalg.norm(delta)
min_dist = 2 * radius
if dist >= min_dist:
continue
# Determine the collision direction when the balls overlap
if dist < 1e-8:
normal = np.array([1.0, 0.0, 0.0])
dist = 0.0
else:
normal = delta / dist
v1 = ball1.speed.get()
v2 = ball2.speed.get()
# Relative velocity
relative_velocity = v2 - v1
velocity_along_normal = np.dot(relative_velocity, normal)
# Only handle collisions when the balls are approaching each other
if velocity_along_normal < 0:
# Perfectly elastic collision between balls of equal mass
impulse = velocity_along_normal * normal
ball1.speed.set(v1 + impulse)
ball2.speed.set(v2 - impulse)
# Resolve the overlap between the two balls
overlap = min_dist - dist
if overlap > 0:
correction = normal * (overlap / 2)
ball1.points.shift(-correction)
ball2.points.shift(correction)
self.play(
GroupStepUpdater(balls, updater),
duration=4,
)
ball_follow = balls[6]
self.forward(0.5)
self.play(
self.camera.anim.points.scale(0.5).move_to(ball_follow),
ball_follow.anim.set(color=YELLOW),
)
self.forward(0.5)
self.play(
GroupStepUpdater(balls, updater),
Follow(self.camera, ball_follow, ORIGIN),
duration=6,
)
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Installation and Quick Start
If you encounter difficulties during installation or have any questions while using it, you can ask questions on the Github Discussions Page or join QQ group 970174336
Basic Tutorials - Understanding Basic Concepts
GUI Tutorials - Using the JAnim GUI
Resource Tutorials - Using External Assets
Advanced Tutorials - Mastering More Practical Mechanisms
Other Tutorials
Other
Example Index
References
Development