Flitter
Flitter is a functional programming language and declarative system for
describing 2D and 3D visuals. It is designed to encourage an iterative,
explorative, play-based approach to constructing visuals.
The language supports
the basic range of functional language features: first-class recursive and
anonymous functions, comprehensions, let/where, conditional expressions, lists
("vectors"). However, unusually, all values are vectors and all operators are
element-wise, and the language is built around constructing trees of attributed
nodes. The language is designed to be familiar to Python programmers.
The engine is able to live reload all code and assets (including any 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 (plus basic pointer and keyboard support).
Flitter is implemented in a mix of Python and Cython and requires at least
OpenGL 3.3 (Core Profile) or OpenGL ES 3.0. At least Python 3.10 is also
required as the code uses match
/case
syntax.
Flitter is designed for expressivity and ease of engine development over
raw performance, but is fast enough to be able to do interesting things.
The engine that runs the language is capable of:
- 2D drawing (loosely
based on an HTML canvas/SVG model)
- 3D rendering,
including:
- primitive box, sphere, cylinder and cone shapes
- external triangular mesh models in a variety of formats including OBJ
and STL
- planar trimming, union, difference and intersection of solid models
- construction of meshes from signed distance fields, including common
combinators and blending functions, and the ability to specify custom
functions
- ambient, directional, point/sphere, line/capsule and spotlight sources
(currently shadowless)
- multiple (simultaneous) cameras with individual control over location,
field-of-view, clip planes, render buffer size, color depth, MSAA samples,
perspective/orthographic projection, fog, conversion to monochrome and
colour tinting
- PBR forward-rendering pipeline with emissive objects, transparency and
translucency, plus the ability to plug in custom GLSL shaders for arbitrary
groups of objects
- texture mapping, including with the output of other visual units (e.g., a
drawing canvas or a video)
- simulating physical particle
systems, including
spring/rod/rubber-band constraints, gravity, electrostatic charge, adhesion,
buoyancy, inertia, drag (including in flowing media), Brownian motion,
uniform electric fields, barriers and particle collisions
- playing videos
at arbitrary speeds (including in reverse)
- running GLSL
shaders as
stacked image filters and generators, with per-frame control of arbitrary
uniforms, and support for multi-pass and downsampling
- built-in filters for: scaling/translating/rotating, Gaussian blurring, bloom,
edge detection, vignetting, video feedback, lens flares, color and exposure
adjustments, tone-mapping with the Reinhard and ACES Filmic functions, and 2D
noise-map generation
- compositing all of the above and rendering to one or more windows
- saving rendered
output to
image and video files (including lockstep frame-by-frame video output
suitable for producing perfect loops and direct generation of animated GIFs)
- taking live inputs from Ableton Push 2 or Behringer X-Touch mini MIDI
surfaces (other controllers relatively easy to add)
- driving arbitrary DMX fixtures via an Entec-compatible USB DMX interface
- driving a LaserCube plugged in over USB (other lasers probably easy-ish to
support)
Flitter also has a plug-in architecture that allows extension with new
image and 3D mesh generators, MIDI and DMX interfaces, or completely novel
input and output systems.
Installation
Flitter can be installed from the flitter-lang
PyPI
package with:
pip3 install flitter-lang
and then run as:
flitter path/to/some/flitter/script.fl
More details can be found in the installation
documentation.
Documentation
The documentation is available on Read the
Docs.
There are a few quick
examples
in the main repository. However, there is also a separate repo containing many
more interesting examples
that are worth checking out.
License
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.