Methods and rewrites
Style rewrites such as set_stroke / set_fill, transform chains like shift / rotate, and the boundaries of save_state / restore and copy.
This page lists 13 examples. The code is imported from corpus/examples/method/; the screenshots are end states rendered on real machines.
set_stroke (mapped to setStyle)
Only the stroke changes (width / colour) while the fill stays as it was — set_stroke wiping the fill was a fixed incident and this case pins it.
"""set_stroke（改写为 setStyle）
@expect 只有描边变了（粗细 / 颜色），填充保持原样——set_stroke 冲掉填充是修过的事故，这条钉它。
@note 2026-10-09 事故：manim-web 的 Mobject 没有 setStroke，当时直接报「无对应方法」
"""
from manim import *
class SetStrokeScene(Scene):
def construct(self):
circle = Circle(radius=1.4, fill_opacity=0.5)
# 并排一颗未改动的对照圆（灰描边）：两颗填充一致，证明 set_stroke 只动了描边
control = circle.copy()
circle.set_stroke(color=RED, width=6)
control.set_stroke(color=GREY)
circle.shift(LEFT * 2.6)
control.shift(RIGHT * 2.6)
self.play(Create(circle), Create(control))
self.wait(0.3)set_opacity (split into stroke + fill)
Stroke and fill fade together; the colour is unchanged.
"""set_opacity（拆成描边 + 填充）
@expect 描边与填充的透明度一起变淡，颜色不变。"""
from manim import *
class SetOpacityScene(Scene):
def construct(self):
circle = Circle(radius=1.4, color=BLUE)
# 左侧放原浓淡对照、右侧变淡后的：颜色不变、浓淡减半
full = circle.copy()
full.shift(LEFT * 2.6)
circle.set_opacity(0.4)
circle.shift(RIGHT * 2.6)
label = Text("透明度 0.4", font_size=28)
label.move_to([2.6, -2.3, 0])
self.play(Create(full), Create(circle), Write(label))
self.wait(0.3)set_fill keyword opacity
The fill becomes the given colour with the given opacity; the stroke is untouched.
"""set_fill 关键字不透明度
@expect 填充色变成指定颜色、透明度生效，描边不受影响。
@note manim-web 的 setFill 把不透明度放在**第二个位置参数**，关键字直传会静默错位
"""
from manim import *
class SetFillScene(Scene):
def construct(self):
square = Square(side_length=2)
square.set_fill(BLUE, opacity=0.5)
self.play(Create(square))
self.wait(0.3)put_start_and_end_on (Line in two steps)
The line's two ends land exactly on the two given points.
"""put_start_and_end_on（Line 拆两步）
@expect 线的两端精确落在指定的两个点上。"""
from manim import *
class PutStartAndEndOnScene(Scene):
def construct(self):
line = Line(start=[-2, -1, 0], end=[2, 1, 0])
line.put_start_and_end_on([-2, 1, 0], [2, -1, 0])
# 两颗灰点钉住指定的两个端点：线两端精确压点而过
ends = VGroup(Dot([-2, 1, 0], color=GREY), Dot([2, -1, 0], color=GREY))
self.play(Create(line), FadeIn(ends))
self.wait(0.3)next_to with buff
The gap between the two mobjects matches the buff value — neither touching nor too far apart.
"""next_to 带 buff
@expect 两物体之间留的空隙与 buff 值一致，不贴死也不离太远。
@note manim-web 的 nextTo 把 buff 放在第三个**位置**参数上
"""
from manim import *
class NextToBuffScene(Scene):
def construct(self):
circle = Circle(radius=1)
square = Square(side_length=1.4, color=YELLOW)
square.next_to(circle, RIGHT, buff=0.5)
self.play(Create(circle), Create(square))
self.wait(0.3)to_edge / to_corner
The mobject sticks to the given edge or corner, keeping a buff from the border.
"""to_edge / to_corner
@expect 物体贴到指定边 / 角，并与边界留出 buff。"""
from manim import *
class EdgeCornerScene(Scene):
def construct(self):
txt = Text("左上角", font_size=36)
txt.to_corner(UL)
dot = Dot(color=RED)
dot.to_edge(DR)
self.play(Write(txt), FadeIn(dot))
self.wait(0.3)shift / move_to / scale / rotate chain
The four calls chain in order; the final position and orientation match the chain.
"""shift / move_to / scale / rotate 链
@expect shift / move_to / scale / rotate 依次链上去，最终位置朝向与链的顺序一致。"""
from manim import *
class ProcessFamilyScene(Scene):
def construct(self):
square = Square(side_length=1.5, color=BLUE)
square.shift(RIGHT * 2)
square.move_to(UP * 1)
square.scale(0.6)
square.rotate(PI / 6)
self.play(Create(square))
self.wait(0.3)arrange_in_grid
A set of mobjects laid out in a tidy grid with the requested rows, columns and spacing.
"""arrange_in_grid
@expect 一组物体排成整齐的网格，行列数与间距按参数。
@note CE 只有一个 buff，manim-web 拆成 buffX / buffY 两个位置参数
"""
from manim import *
class ArrangeGridScene(Scene):
def construct(self):
dots = VGroup(*[Dot(radius=0.15) for _ in range(4)])
dots.arrange_in_grid(rows=2, cols=2, buff=0.8)
self.play(FadeIn(dots))
self.wait(0.3)save_state / restore
After the changes, restore returns the mobject to its save_state look — position, size and style all back.
"""save_state / restore
@expect 改动后 restore 回到 save_state 时的样子（位置 / 大小 / 样式都回去）。
@note CE 的 restore() 在 manim-web 叫 restoreState()
"""
from manim import *
class SaveRestoreScene(Scene):
def construct(self):
square = Square(side_length=2, color=BLUE)
square.save_state()
self.add(square)
self.play(square.animate.shift(RIGHT * 2).set_color(RED))
# 改动后的红色偏移副本留作影子：restore 后与居中蓝方块同框对照
ghost = square.copy()
square.restore()
self.add(ghost)
self.wait(0.3)become swaps the shape
After playback the mobject has become the target shape; become replaces rather than copies.
"""become 换形
@expect 播完后物体变成了目标形状（become 是直接换形，不是复制一份）。"""
from manim import *
class BecomeScene(Scene):
def construct(self):
circle = Circle(radius=1, color=BLUE)
square = Square(side_length=2, color=YELLOW)
self.add(square)
# become 前存方块 ghost：become 后灰方块轮廓与蓝圆并存，直接看出「换形」
ghost = square.copy().set_stroke(GREY, opacity=0.35)
square.become(circle)
label = Text("become 换形", font_size=26)
label.move_to([0, -2.2, 0])
self.add(ghost, label)
self.wait(0.3)Reading the width attribute
The printed width matches the mobject's real width (the numeric assertion is authoritative).
"""读 width 属性
@expect print 出的 width 与物体实际宽度一致（数值断言为准）。
@note 适配层的 __getattr__ 对任何名字都返回函数，读属性必须走 PROP_READS 的真取法
"""
from manim import *
class AttrReadScene(Scene):
def construct(self):
square = Square(side_length=2)
w = square.width
txt = Text("宽 " + str(round(w, 2)), font_size=32)
txt.to_corner(DL)
self.play(Create(square), Write(txt))
self.wait(0.3)get_center used for placement
A mobject placed with get_center's return value has its centre exactly where expected.
"""get_center 参与定位
@expect 用 get_center 的返回值定位出的物体，中心正落在预期位置。"""
from manim import *
class GetCenterScene(Scene):
def construct(self):
circle = Circle(radius=1, color=BLUE)
dot = Dot(point=circle.get_center() + UP * 2, color=RED)
self.play(Create(circle), FadeIn(dot))
self.wait(0.3)copy produces a new mobject
Changing the copy leaves the original untouched — the two are independent and share no style.
"""copy 出新物体
@expect 副本改动后原件不动——两者独立，不串样式。"""
from manim import *
class CopyScene(Scene):
def construct(self):
circle = Circle(radius=1, color=BLUE)
copy = circle.copy()
copy.shift(RIGHT * 3).set_color(GREEN)
self.play(Create(circle), Create(copy))
self.wait(0.3)