manim

Manim (Programmatic Math Animation)

Manim (Mathematical Animation Engine, Community Edition) renders explanatory math/physics/CS videos from Python — the engine behind 3Blue1Brown-style motion. Every scene is declarative: you build vector objects, play timed animations over them, and render a deterministic MP4/GIF from the CLI. Best-in-class for moving equations, transforming formulas, animated graphs, and geometric intuition.

When to use

• Animate an equation: write it on, transform it term-by-term, highlight substitutions.
• Visualize a function/graph: axes, plotted curves, a dot tracing the curve, area under it.
• Geometric or conceptual explainers: a proof unfolding, vectors, transformations, number lines.
• 3D math: surfaces, parametric curves, a camera orbiting a shape.
• Any "show the math moving" educational clip rendered to MP4/GIF.

Not the tool for UI motion, social/marketing video, or data-from-CSV business charts — use the web-animation or Remotion video skills for those. Manim's edge is mathematical typesetting and intuition.

Setup & render

pip install manim          # needs Python 3.9+, ffmpeg, and a LaTeX distribution (for Tex/MathTex)
manim -pql scene.py SquareToCircle   # render one Scene class, preview at low quality

Render flags (the ones that matter):

• -q l|m|h|k — quality: low (fast iteration) → 4K. -ql while building, -qh to ship.
• -p — play when done; -o name — output filename; --format=gif — render a GIF (README demos).
• -s — save the last frame as a PNG (no video encode — the verification lever, see below).
• -n a,b — render only animation index range a..b (stop early to inspect a moment).
• Output lands in media/videos/<file>/<quality>/<Scene>.mp4 (and media/images/... for -s).

The three building blocks

Everything is Scenes (orchestration) acting on Mobjects (objects) via Animations (timed change).

Mobjects — vector objects (Circle, Square, Rectangle, Line, Dot, Polygon, Axes, Text, MathTex).

• Position: .shift(UP*2) (relative), .move_to(ORIGIN) (absolute), .next_to(other, RIGHT, buff=0.5), .align_to(other, LEFT). Directions are constants: UP DOWN LEFT RIGHT ORIGIN UL UR DL DR.
• Style: .set_fill(color, opacity), .set_stroke(color, width), .set_color(YELLOW). Colors: BLUE RED GREEN YELLOW WHITE + BLUE_E, etc.
• self.add(m) shows instantly (no animation); self.remove(m). Later-added objects render on top.

Animations — interpolate a mobject's state over run_time seconds (default 1s).

• Construction: Create, Write (for text/Tex), DrawBorderThenFill, FadeIn, FadeOut, GrowFromCenter.
• Change: Transform(a, b) (morph a into b, keep a), ReplacementTransform(a, b) (swap a for b), Rotate, Indicate, Circumscribe, Wiggle.
• .animate syntax — animate any method call: self.play(sq.animate.shift(UP).set_fill(RED)). Chains apply together.
• Play several at once: self.play(Create(a), FadeIn(b), run_time=2).

Timing & easing — run_time= sets duration; rate_func= sets the easing curve (smooth is the default — ease-in-out; also linear, rush_into, rush_from, there_and_back, ease_out_bounce). Stagger a group with LaggedStart(*anims, lag_ratio=0.2). The motion-craft rules from the motion-design-skills pack (animation-principles: the eye forgives a slow end less than a slow start; reserve linear for loops; stagger groups) apply here — Manim just expresses them as rate_func + LaggedStart.

Math, text & equations

Text/MarkupText (Pango, no LaTeX) for labels; Tex/MathTex (LaTeX, raw strings) for typeset math. Animate equations with Write and morph between them with TransformMatchingTex. Full recipes — substring coloring, {{ }} isolation, term-by-term transforms, LaTeX preamble — in references/math-and-text.md.

Graphs, plotting & updaters

Axes + ax.plot(lambda x: ...) for functions; ax.c2p(x, y) maps math coords → screen. Drive live values with ValueTracker + always_redraw/add_updater so dependent mobjects recompute every frame (a dot riding a curve, a counter, a moving tangent). See references/graphs-and-updaters.md.

3D & moving camera

ThreeDScene + set_camera_orientation(phi=, theta=), ThreeDAxes, Surface, begin_ambient_camera_rotation(); MovingCameraScene + self.camera.frame.animate... for 2D camera pushes/follows. See references/3d-and-camera.md.

Deliver & verify (rendered frame → MP4)

Packaged helper (scripts/): tile your stills with scripts/contact-sheet.sh sheet.png f-hook.png f-mid.png f-end.png, then assert the encode with scripts/probe-mp4.sh out.mp4 [WxH] [fps]. See scripts/README.md.

Manim is deterministic — the same scene renders the same frames — so verify by rendering frames (PNG, no video encode) before committing to the full video. Use this whenever the output is a math clip MP4/GIF.

Output contract:

• A .py with one Scene (or ThreeDScene) subclass per clip; all motion inside construct(). Deliverable = the rendered media/videos/.../<Scene>.mp4 plus the script (so it re-renders).
• Raw strings (r"...") for every Tex/MathTex; LaTeX installed.

Verify loop — render frames → inspect → encode video:

Before you finish:

1. manim -sql ... -n a,b renders cleanly at start / a mid range / end — no LaTeX errors, no missing-glyph boxes.
2. Equations/labels are mathematically correct and fully inside the frame (nothing clipped at edges).
3. No overlap between mobjects at the inspected frames; next_to/arrange used instead of hand-guessed coords.
4. Timing reads well — run_time/rate_func intentional, self.wait() holds on key states, groups staggered not simultaneous.
5. Full MP4 encodes and plays; (optional) GIF rendered for the README.

Quick reference

Gotchas

• LaTeX is required for Tex/MathTex (not for Text). A missing-glyph box or compile error = LaTeX not installed or a bad TeX string. Always use raw strings r"...".
• Transform(a, b) mutates a to look like b (and b is not added); ReplacementTransform(a, b) leaves b on screen — pick based on which object you keep referencing after.
• .animate interpolates start→end states, so it can take odd paths for rotations/some transforms; use a dedicated animation (Rotate) when the path matters.
• Updaters added with add_updater keep running — mob.clear_updaters() (or remove_updater) when done, or later animations fight the updater.
• Don't hand-guess coordinates; compose with next_to, arrange, VGroup(...).arrange(DOWN), and ax.c2p() so layout survives edits.
• construct() runs once to script the timeline; there is no realtime loop — never use wall-clock time or randomness without a seed.

Reference files

• references/math-and-text.md — Text vs MarkupText vs Tex vs MathTex, raw strings, substring coloring (set_color_by_tex, substrings_to_isolate, {{ }}), TransformMatchingTex term morphs, and LaTeX preamble/packages.
• references/graphs-and-updaters.md — Axes/NumberPlane, plot, get_area, c2p/p2c, ValueTracker, always_redraw, add_updater, a dot tracing a curve, and animated counters.
• references/3d-and-camera.md — ThreeDScene, set_camera_orientation, ThreeDAxes, Surface/parametric, ambient camera rotation, and MovingCameraScene pushes/follows.