Manim Scroll

Scroll-driven Manim animations for the web. Pre-render mathematical animations with Manim and play them back smoothly as users scroll.

Quick Start (Next.js)

The recommended approach uses the Next.js plugin for automatic build-time rendering.

1. Install the unified package:

npm install @mihirsarya/manim-scroll

2. Configure next.config.js:

const { withManimScroll } = require("@mihirsarya/manim-scroll/next");

module.exports = withManimScroll({
  manimScroll: {
    pythonPath: "python3",
    quality: "h",
    fps: 30,
    resolution: "1920x1080",
  },
});

3. Use the component:

import { ManimScroll } from "@mihirsarya/manim-scroll";

export default function Page() {
  return (
    <ManimScroll
      scene="TextScene"
      fontSize={72}
      color="#ffffff"
      scrollRange="viewport"
      style={{ height: "100vh", background: "#111" }}
    >
      Welcome to my site
    </ManimScroll>
  );
}

The plugin automatically extracts props, renders animations, and caches them.

Native Mode (No Pre-rendered Assets)

For text animations without pre-rendered video/frames, use native mode. This renders text directly in the browser using SVG, replicating Manim's Write/DrawBorderThenFill animation.

<ManimScroll
  mode="native"
  fontSize={48}
  color="#ffffff"
  scrollRange="viewport"
  style={{ height: "100vh", background: "#111" }}
>
  Currently building
</ManimScroll>

Native Mode Benefits

• No build step required - works immediately without Python/Manim
• Perfect sizing - text renders at exact pixel size (no scaling artifacts)
• Smaller bundle - no video/frame assets to download
• Authentic Manim animation - replicates Write/DrawBorderThenFill exactly:
  • Uses Manim's exact lag_ratio = min(4.0 / length, 0.2) formula
  • Two-phase animation: stroke drawing (0-50%) and fill transition (50-100%)
  • Progressive contour drawing across all characters
  • Matches Manim's linear rate function for Write animation
• Scroll-driven - same scroll progress behavior as pre-rendered mode

Custom Fonts in Native Mode

For authentic Manim typography, provide a font URL (woff, woff2, ttf, otf):

<ManimScroll
  mode="native"
  fontSize={48}
  color="#ffffff"
  fontUrl="/fonts/CMUSerif-Roman.woff2"
>
  Mathematical text
</ManimScroll>

Progress-Based Animation (No Scroll)

Animate text programmatically via progress value or duration instead of scroll.

Controlled Progress Mode

Pass progress prop (0-1) to render at exact animation state:

const [progress, setProgress] = useState(0);

<ManimScroll mode="native" progress={progress}>
  Hello World
</ManimScroll>

<input 
  type="range" 
  value={progress} 
  onChange={(e) => setProgress(+e.target.value)} 
  min={0} max={1} step={0.01} 
/>

Imperative Playback with Hook

Use useNativeAnimation for programmatic control:

import { useRef, useEffect } from "react";
import { useNativeAnimation } from "@mihirsarya/manim-scroll";

function AutoPlayDemo() {
  const containerRef = useRef<HTMLDivElement>(null);
  
  const { isReady, play, seek, setProgress, isPlaying } = useNativeAnimation({
    ref: containerRef,
    text: "Hello World",
    fontSize: 72,
    color: "#ffffff",
  });

  // Auto-play on mount
  useEffect(() => {
    if (isReady) {
      play(2000); // Play over 2 seconds
    }
  }, [isReady, play]);

  return (
    <div ref={containerRef}>
      <button onClick={() => play(1000)}>Play</button>
      <button onClick={() => seek(0.5)}>Jump to 50%</button>
      <button onClick={() => setProgress(0)}>Reset</button>
    </div>
  );
}

Playback Options

The play() method accepts options for fine-grained control:

play({
  duration: 2000,           // Animation duration in ms
  delay: 500,               // Delay before starting
  easing: "ease-in-out",    // Easing: "linear" | "ease-in" | "ease-out" | "ease-in-out" | "smooth"
  loop: true,               // Loop animation
  direction: -1,            // Reverse playback
  onComplete: () => {},     // Callback when done
});

useNativeAnimation Hook

Full programmatic control:

import { useRef } from "react";
import { useNativeAnimation } from "@mihirsarya/manim-scroll";

function NativeDemo() {
  const containerRef = useRef<HTMLDivElement>(null);
  
  const { progress, isReady, pause, resume, play, seek, setProgress, isPlaying } = useNativeAnimation({
    ref: containerRef,
    text: "Hello World",
    fontSize: 72,
    color: "#ffffff",
    scrollRange: "viewport", // Ignored when using play()/setProgress()
  });

  return (
    <div ref={containerRef} style={{ height: "100vh" }}>
      {!isReady && <div>Loading...</div>}
    </div>
  );
}

Inline Mode

For animations that flow with surrounding text (like within a paragraph):

<p>
  I'm building{" "}
  <ManimScroll
    scene="TextScene"
    fontSize={24}
    color="#667eea"
    inline
    style={{ width: "150px", height: "30px" }}
  >
    the future
  </ManimScroll>{" "}
  today.
</p>

Inline mode:

• Renders with a transparent background
• Uses display: inline-block for flow with text
• Adjusts the Manim camera to fit text tightly with minimal padding
• Outputs WebM with alpha channel (for video mode) or transparent PNGs (for frames mode)

Scroll Range Configuration

Control when the animation plays relative to scroll position.

Presets (Recommended)

<ManimScroll scrollRange="viewport">...</ManimScroll>  // Default: plays as element crosses viewport
<ManimScroll scrollRange="element">...</ManimScroll>   // Tied to element's own scroll position
<ManimScroll scrollRange="full">...</ManimScroll>      // Spans entire document scroll

Relative Units

<ManimScroll scrollRange={["100vh", "-50%"]}>...</ManimScroll>
<ManimScroll scrollRange={["80vh", "-100%"]}>...</ManimScroll>

Supported units:

• vh - viewport height percentage
• % - element height percentage
• px - pixels
• Plain numbers - treated as pixels

Pixel Values (Legacy)

<ManimScroll scrollRange={{ start: 800, end: -400 }}>...</ManimScroll>
<ManimScroll scrollRange={[800, -400]}>...</ManimScroll>

useManimScroll Hook

For advanced use cases requiring custom control:

import { useRef } from "react";
import { useManimScroll } from "@mihirsarya/manim-scroll";

function CustomAnimation() {
  const containerRef = useRef<HTMLDivElement>(null);

  const { progress, isReady, error, pause, resume, seek, isPaused } = useManimScroll({
    ref: containerRef,
    manifestUrl: "/assets/scene/manifest.json",
    scrollRange: "viewport",
  });

  return (
    <div ref={containerRef} style={{ height: "100vh" }}>
      {!isReady && <div>Loading...</div>}
      <div>Progress: {Math.round(progress * 100)}%</div>
      <button onClick={pause}>Pause</button>
      <button onClick={resume}>Resume</button>
    </div>
  );
}

Auto-Resolution Mode

When using with the Next.js plugin, you can let the hook resolve the manifest automatically:

const { progress, isReady } = useManimScroll({
  ref: containerRef,
  scene: "TextScene",
  animationProps: { text: "Hello", fontSize: 72, color: "#fff" },
});

Vanilla JS Usage

Pre-rendered Animations

import { registerScrollAnimation } from "@mihirsarya/manim-scroll-runtime";

const container = document.querySelector("#hero") as HTMLElement;

registerScrollAnimation({
  container,
  manifestUrl: "/dist/scene/manifest.json",
  mode: "auto",
  scrollRange: "viewport",
  onReady: () => console.log("ready"),
  onProgress: (progress) => console.log(progress),
});

Native Text Animations

import { registerNativeAnimation } from "@mihirsarya/manim-scroll-runtime";

const container = document.querySelector("#hero") as HTMLElement;

registerNativeAnimation({
  container,
  text: "Animate this",
  fontSize: 72,
  color: "#ffffff",
  scrollRange: "viewport",
  onReady: () => console.log("ready"),
});

Manual Rendering (Non-Next.js)

For custom workflows, use the Python CLI directly:

python render/cli.py \
  --scene-file path/to/scene.py \
  --scene-name MyScene \
  --output-dir ./dist/scene \
  --format both \
  --fps 30 \
  --resolution 1920x1080 \
  --quality k

Render Text with Props

echo '{"text": "Hello World", "fontSize": 72, "color": "#ffffff"}' > props.json

python render/cli.py \
  --scene-file render/templates/text_scene.py \
  --scene-name TextScene \
  --props props.json \
  --output-dir ./dist/scene \
  --format both

CLI Options

Package Structure

Next.js Plugin Configuration

Component Props Reference

Requirements

• Python 3.8+ with Manim installed (for pre-rendered mode)
• Node.js 18+
• Next.js 13+ (for the plugin)

Additional Resources

• See references/ARCHITECTURE.md for package internals and diagrams
• See references/API.md for complete type definitions
• See references/CUSTOM_SCENES.md for creating custom Manim scenes
• See references/TROUBLESHOOTING.md for common issues and solutions