README

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This template demonstrates how to integrate WebGL shaders with tldraw, creating dynamic backgrounds that respond to canvas interactions. It includes four complete examples and a reusable WebGLManager base class for building custom shader effects.

Local development

Install dependencies with yarn or npm install.

Run the development server with yarn dev or npm run dev.

Open http://localhost:5173/ in your browser to see the app.

What's included

• WebGLManager base class (src/WebGLManager.ts) - Handles WebGL lifecycle, viewport synchronization, and animation loop integration with tldraw's reactive system
• Four example shaders - Fluid simulation, rainbow gradients, dynamic shadows, and a minimal starter template
• Config panel components (src/config-panel/) - Pre-built UI controls for adjusting shader parameters with localStorage persistence
• Full TypeScript support - Strongly typed throughout

Switch between examples using the toggle buttons in the tldraw style panel.

Examples

Fluid Simulation

A real-time fluid simulation that creates dynamic flows from shape interactions. Based on Pavel Dobryakov's WebGL fluid implementation.

• Navier-Stokes fluid dynamics
• Shape movements create velocity-based splats
• Configurable physics and visual effects

See: src/fluid/ | Documentation

Rainbow

An animated gradient shader demonstrating time-based effects and uniform management.

See: src/rainbow/

Shadows

Dynamic shadow casting from tldraw shapes using raymarching and signed distance fields.

See: src/shadow/

Minimal

A bare-bones template for starting new shader projects. Renders a solid color that adapts to dark mode.

See: src/minimal/ | Documentation

Architecture

WebGLManager

The WebGLManager class (src/WebGLManager.ts) provides the foundation for all shader examples. It handles:

• WebGL2 context creation and lifecycle management
• Automatic viewport synchronization with tldraw's canvas
• Animation loop with lifecycle hooks: onInitialize(), onUpdate(), onRender(), onDispose()
• Quality/resolution management
• Integration with tldraw's reactive state system

To create a custom shader, extend WebGLManager and implement the lifecycle hooks. See the minimal example for a starting point.

Config Panel

The config panel system (src/config-panel/) provides reusable UI components for creating interactive shader controls:

• ConfigPanel - Collapsible container with reset functionality
• ConfigPanelSlider - Numeric slider control
• ConfigPanelBooleanControl - Checkbox control

Config values are stored in reactive atoms and automatically persisted to localStorage. See config-panel.md for usage details.

Renderer Pattern

Each example follows this pattern:

1. Define a config interface extending WebGLManagerConfig in config.ts
2. Create a shader manager class extending WebGLManager
3. Write GLSL shaders (vertex and fragment)
4. Create a React renderer component using useLayoutEffect to initialize the manager
5. Build a config panel for live parameter adjustment
6. Register the renderer as tldraw's Background component

See any of the example directories for complete implementations.

Creating a custom shader

The fastest way to create a custom shader is to copy the minimal example:

cp -r src/minimal src/my-shader

Then customize the following files:

• config.ts - Define your configuration parameters
• fragment.glsl / vertex.glsl - Write your shader code
• MyShaderManager.ts - Extend WebGLManager and implement rendering logic
• MyRenderer.tsx - Create the React component
• MyConfigPanel.tsx - Build UI controls

Finally, register your shader in src/App.tsx.

For a detailed walkthrough, see src/minimal/minimal-example.md.

Integration with tldraw

The WebGLManager has direct access to the tldraw editor instance, allowing you to:

• Access shapes: this.editor.getCurrentPageShapes()
• Listen to shape changes: this.editor.store.listen()
• Get camera state: this.editor.getCamera()
• Convert coordinates: this.editor.pageToViewport()
• Track pointer position: this.editor.inputs.currentPagePoint

The fluid simulation example (src/fluid/FluidManager.ts) demonstrates shape integration in depth.

Resources

• WebGL2 Fundamentals - WebGL tutorials
• The Book of Shaders - GLSL shader programming
• Shadertoy - Shader examples
• tldraw Documentation - tldraw SDK docs

License

This project is provided under the MIT license found here. The tldraw SDK is provided under the tldraw license.

Trademarks

Copyright (c) 2024-present tldraw Inc. The tldraw name and logo are trademarks of tldraw. Please see our trademark guidelines for info on acceptable usage.

Distributions

You can find tldraw on npm here.

Contribution

Please see our contributing guide. Found a bug? Please submit an issue.

Community

Have questions, comments or feedback? Join our discord. For the latest news and release notes, visit tldraw.dev.

Contact

Find us on Twitter/X at @tldraw.