manim-scenes

name	manim-scenes
description	Use when authoring or editing Manim Community Edition (manim-ce) scenes. Covers the Scene/Mobject model, the construct() lifecycle, the add/play distinction, coordinate system and direction constants, common Mobjects (Text, MathTex, geometric shapes), MathTex/LaTeX error triage, project workflow for multi-scene videos, and the gotchas that distinguish manim-ce from 3b1b's manimgl.

Manim scenes

This skill is for Manim Community Edition (manim-ce, import manim), not 3Blue1Brown's manimgl. They have diverged: APIs that work in one often don't in the other. Check first which one the project uses.

Anatomy

from manim import *

class HelloWorld(Scene):
    def construct(self):
        title = Text("Hello, world!", color=BLUE)
        self.play(Write(title))
        self.wait()
        self.play(FadeOut(title))

• Scene is the base class. Each scene becomes one rendered video.
• construct(self) is where the animation happens. Called once when rendering.
• Mobjects (mathematical objects) are the things you animate.
• self.play(...) animates one or more changes over time.
• self.add(...) instantly adds an Mobject without animating it.
• self.wait(seconds=1.0) pauses (renders static frames).

The Mobject zoo

Geometric:

Square(side_length=2, color=RED)
Circle(radius=1, color=BLUE)
Rectangle(width=4, height=2)
Triangle()
Polygon(*[ [-1,0,0], [1,0,0], [0,1.5,0] ])
Line(start=LEFT, end=RIGHT)
Arrow(start=ORIGIN, end=UR)
Dot(point=ORIGIN, radius=0.08)

Text:

Text("plain text", font="Arial", weight=BOLD)
MathTex(r"e^{i\pi} + 1 = 0")           # LaTeX math
Tex(r"Inline \(\alpha\) text")          # LaTeX with text
MarkupText("<b>bold</b> and <i>italic</i>")  # Pango markup

MathTex parts are addressable: eq = MathTex("a","+","b","=","c"); eq[2] is the b. Use this for transformations.

Coordinate system and direction constants

Manim's frame is centered at the origin, x-right, y-up, z-out-of-screen. The visible frame is about ±7 in x and ±4 in y.

Standard direction vectors (numpy arrays):

ORIGIN = [0, 0, 0]
UP, DOWN, LEFT, RIGHT
UR (= UP+RIGHT), UL, DR, DL
IN (into screen), OUT

Positioning:

square.move_to(ORIGIN)              # absolute position
square.shift(2 * RIGHT)             # relative
square.next_to(circle, RIGHT, buff=0.5)  # adjacent placement
square.align_to(circle, LEFT)       # align edges
square.to_edge(UP)                  # snap to frame edge
square.to_corner(UL)                # snap to corner

These return the Mobject, so they chain: Square().shift(UP).set_color(RED).

add vs play vs animate

Three ways to change the scene:

Form	When	Animated?
self.add(m)	Appears instantly at start of next render frame	No
self.play(Create(m))	Animate construction over run_time seconds	Yes
self.play(m.animate.shift(UP))	Animate the result of m.shift(UP)	Yes

The .animate syntactic sugar:

self.play(square.animate.shift(RIGHT).scale(2))
# equivalent to a single animation that ends with square shifted+scaled

run_time controls duration: self.play(Write(t), run_time=2).

Groups

group = VGroup(square, circle, triangle)
group.arrange(RIGHT, buff=0.5)
self.play(FadeIn(group))

VGroup is for vector mobjects (most things). Group is for any mobjects mixed (e.g., images + vectors).

The self.camera.background_color trick

To match a slide deck or a particular theme:

self.camera.background_color = "#1f1f1f"

Or set globally in manim.cfg next to the script.

Common gotchas

1. Modifying a Mobject after self.play doesn't animate it. self.play records the animation; mutating the Mobject afterward changes its current state silently. Use .animate if you want an animation.
2. MathTex vs Tex. MathTex wraps in math mode; Tex doesn't. Mixing is a common source of "command not recognized" errors.
3. Text requires a TrueType font that Pango can find. Custom fonts: Text(..., font="MyFont") plus register_font() if not system-installed.
4. Background isn't transparent by default for mp4 output. Use -t (or --transparent) and .mov (ProRes) for transparent renders.
5. self.wait() at the end. If you skip it, the last frame is held for 0 seconds. Most exports look cut-off without a final wait.

MathTex error triage

LaTeX failures are the most common broken-render cause after API misuse. Triage in this order:

1. Raw strings, always. MathTex(r"\frac{a}{b}"). Without r, \f is a form feed and manim sends LaTeX garbage.
2. f-strings double the braces. MathTex(rf"x^{{{n}}}"), since LaTeX's {} collide with f-string interpolation.
3. "LaTeX Error" in manim output means the .tex compile failed. It's a LaTeX problem, not a Python one. Read the .log file the error points to (under media/Tex/); the offending line is quoted there. "Undefined control sequence" usually means a missing package, added via a template:

   tpl = TexTemplate()
   tpl.add_to_preamble(r"\usepackage{mathrsfs}")
   MathTex(r"\mathscr{L}", tex_template=tpl)
   

4. Build multi-part equations as substrings so animations have targets:

   eq = MathTex("a^2", "+", "b^2", "=", "c^2")
   eq[0]                        # a^2
   SurroundingRectangle(eq[2])  # b^2
   

   A single-string MathTex is one blob, so eq[i], SurroundingRectangle, and TransformMatchingTex have nothing to grab. For finer splits without restructuring: MathTex(r"e^x = x^e", substrings_to_isolate="x").
5. No LaTeX installed: every MathTex/Tex render fails. manim needs a system LaTeX (texlive-full / MiKTeX) plus dvisvgm. Text() and MarkupText() do not.

Project workflow (multi-scene videos)

For anything longer than one scene:

1. Write plan.md first: the narrative arc, one line per scene, and the color palette (concept → color).
2. One class per scene, numbered: Scene1_Setup, Scene2_Theorem, Scene3_Derivative. Render order is explicit in the name.
3. Render only the scenes you changed: manim -ql video.py Scene3_Derivative.
4. Assemble with ffmpeg concat:

   printf "file '%s'\n" media/videos/video/480p15/Scene*.mp4 > concat.txt
   ffmpeg -f concat -safe 0 -i concat.txt -c copy full.mp4
   

   Globs sort lexically, so zero-pad (Scene01_…) past nine scenes.

Rendering CLI

manim -pql scene.py SceneName       # quick preview (480p, 15fps)
manim -pqm scene.py SceneName       # medium (720p, 30fps)
manim -pqh scene.py SceneName       # high (1080p, 60fps)
manim -pqk scene.py SceneName       # 4K

Flags:

• -p = play after render
• -q{l,m,h,k} = quality
• -s = render only the last frame as PNG
• -t = transparent background

Output goes to ./media/videos/<file>/<quality>/<SceneName>.mp4 by default.

Related: [[manim-animations]], [[manim-3d]].