Flitter

Flitter is a functional programming language and declarative system for describing 2D and 3D visuals. The language is designed to encourage an iterative, explorative, play-based approach to constructing visuals.

The engine is able to live reload all code and assets (including shaders, images, videos, models, etc.) while retaining the current system state - thus supporting live-coding. It also has support for interacting with running programs via MIDI surfaces.

Flitter is designed for expressivity and ease of engine development over raw performance, but is fast enough to be able to do interesting things.

Documentation

• Background
  • Where did Flitter come from?
  • A note about the name
• Installing and Running
  • Installing Flitter
  • Running Flitter
  • Developing Flitter
• Tutorial
  • Declarative Visuals
  • Named Values
  • Functions
  • For Loops
  • Animation
  • Template Functions
  • If Expressions
  • Summary
• The Language
  • Quick introduction
  • Unicode Support
  • Comments
  • Values
  • Ranges
  • Indexing
  • Operators
  • Let Expressions
  • Sequences
  • Conditionals
  • For Loops
  • Function calling
  • Function Definitions
  • Template function calls
  • State
  • Pragmas
  • Imports
  • Includes
  • Parsing
  • Simplification
  • Run-time Error Behaviour
• Built-in Functions
  • Vector utility functions
  • Mathematical functions
  • Quaternion functions
  • Matrix functions
  • Waveform functions
  • Easing functions
  • Pseudo-random functions
  • Noise functions
  • Color functions
  • Text functions
  • File functions
  • Texture sampling
• Windows
  • Common attributes
  • !window and !offscreen
  • !image
  • !video
  • !record
  • !reference
• Shaders
  • !shader
  • Shader templating
  • Built-in image filters and generators
• 2D Drawing
  • Overview
  • Canvases
  • Groups
  • Layers
  • Transforms
  • Paints
  • Fonts
  • Paths
  • Text
  • Images
  • Shaders
  • Image Filters
  • Path Effects
  • Blend modes
• 3D Rendering
  • Overview
  • 3D Canvases
  • Transforms
  • Render Groups
  • Cameras
  • Lights
  • Materials
  • Models
  • Constructive Solid Geometry
  • Signed Distance Fields
• Counters
  • Counter State
  • Example
• Physics Simulation
  • Nodes
  • Barriers
  • Groups
  • State interaction
  • Example
• Using Controllers
  • Controller Configuration
  • Actions
  • Supported Controllers

Examples

Some simple examples are included in the source but many more can be found at the Flitter examples repo.

Papers and presentations

There is a paper discussing the background and design of Flitter that was presented at the Alpaca 2025 conference. You can also watch a video of the accompanying talk, which demonstrates writing a simple Flitter program from scratch to generate some animated 3D visuals.

License and Development

Flitter is copyright © Jonathan Hogg and licensed under a 2-clause “simplified” BSD license except for the OpenSimplex 2S noise implementation, which is based on code copyright © A. Svensson and licensed under an MIT license.

The complete source code is available in the GitHub Flitter repo, which also hosts the issues tracker. The official release packages are available in the PyPI flitter-lang package.