glowdrift

An original full-frame terminal screensaver. Rainbow particles drift through an organic, slowly-evolving flow field, depositing additive glow that decays into trails on a dark background. Truecolor, half-block rendering (two pixels per character row), keyboard-controlled, quits on q.

Install

Homebrew (macOS / Linux):

brew install dnvsfn/tap/glowdrift

pipx (any platform):

pipx install glowdrift               # or:  pip install --user glowdrift
pipx install 'glowdrift[render]'     # + Pillow, for PNG output

From source:

git clone https://github.com/dnvsfn/glowdrift
cd glowdrift
make install                 # copies to ~/.local/bin/glowdrift

Make sure ~/.local/bin is on your PATH (or sudo make install PREFIX=/usr/local).

Live playback is pure Python 3 (3.8+) with no dependencies; Pillow is only needed for the PNG-output flags (--render, --gallery, --contact).

Run

glowdrift                       # screensaver: drift between presets (any key quits)
glowdrift --still               # hold one fixed default look instead
glowdrift aurora                # a named preset, held (see below)
glowdrift synthwave --speed 2   # a preset with one knob overridden
glowdrift --random --seed 12    # roll a whole random look from a seed
glowdrift --swirl 0.2 --flow-bias 25              # parallel streams flowing down-right
glowdrift --hue-center 205 --hue-range 70         # limit to a blue/cyan palette
glowdrift --colors 3 --edge 0.9                   # 3 crisp colors, hard-edged strokes

Screensaver mode

With no arguments, glowdrift runs as a screensaver: it slowly drifts from one look to the next forever, crossfading the flow so the trails carry across each transition (no hard cuts). Naming a preset or setting any knob instead holds that single look; --still forces the fixed default look.

glowdrift                                          # the default: drift through the presets
glowdrift --cycle --random                         # drift through endless random rolls
glowdrift --cycle-hold 30 --cycle-fade 12          # linger longer, morph slower

Playing live

While it's running, glowdrift is interactive. Press h for the on-screen help; a status bar shows the current look and the selected knob.

key	action	key	action
[ ]	previous / next preset	1-0	jump to a preset
m M	step the motion model	d D	step the direction field
r	roll a random look	c	toggle the auto-cycle drift
← →	select a knob	↑ ↓ (or + -)	dial it live
k	kaleidoscope fold	x	pixelate blocks
g	glitch	i / l	dither / scanlines
space	pause	s	pin this look to ~/.glowdrift-pins
h ?	toggle help	q Esc	quit

Touching any control drops out of the auto-cycle so your edits stick, and the exact flags to reproduce whatever you were watching print when you quit.

Pattern & render styles

Opt-in layers that restyle any look (composable, and toggleable live):

glowdrift aurora --symmetry 6      # kaleidoscope: N-fold mirror into a mandala
glowdrift neon --pixelate 4        # chunky NxN pixel blocks
glowdrift synthwave --glitch 0.6   # row tearing + RGB channel split
glowdrift oceanic --dither         # ordered dithering, retro halftone
glowdrift aurora --scanlines       # dim alternate rows, CRT look

(--cycle requests cycling explicitly. It's implied by a bare launch, but you need it to cycle random rolls, since --random on its own holds one fixed look. --cycle-hold / --cycle-fade also imply it.)

Presets

Twenty-eight hand-tuned looks, each with its own motion model, and many now baking in a kaleidoscope or render style. Run one by name; any flag you add still overrides it (glowdrift synthwave --speed 2, glowdrift mandala --symmetry 3).

aurora — curl eddies, green/teal/violet, slow	nebula — orbit swirl, violet/indigo cosmic bloom
ember — inertial flames rising, warm reds/orange	oceanic — flow strands drifting sideways, blue/cyan
neon — inertial sweeps, scanlined arcade rainbow	whirlpool — flow vortices, blue/cyan water swirl, fills the frame
sonar — flow ripples, dithered green scope	synthwave — flow streams, magenta + cyan, scanlined
moss — curl eddies, dense soft greens	prism — harmonograph loops as a rainbow gem
smoke — jitter drift, cool tinted haze	bloom — spiral petals mirrored into a flower mandala
pinwheel — spin field, rainbow rotating vortex	rift — saddle field, cool hyperbolic streams
swarm — levy bursts, clustered whirlpools	chaos — pendulum swings, energetic red/gold fire cloud
mandala — 6-fold curl kaleidoscope, full rainbow	rosette — 8-fold harmonograph lace rosette
snowflake — 6-fold saddle, dithered icy crystal	gyro — 4-fold pendulum, chaotic rainbow mandala
arcade — pixelated + scanlined inertial neon	8bit — chunky pixelated flow vortices, amber/gold
datamosh — heavy glitch tearing, magenta/cyan	signal — levy ripples, glitched broken transmission
halftone — curl swirls, magenta pop-art dither	plasma — curl flow, emerald demoscene dithered plasma
terminal — flow waves, dithered green CRT	vhs — spin vortex, glitched + scanlined tape

glowdrift --list              # list presets with their motion + mode
glowdrift --gallery --out /tmp/presets   # render every preset to a labeled grid

Previews live in previews/; regenerate them with make-previews.sh.

Pure Python 3, no dependencies (PIL only needed for --render/--contact). Best in a truecolor terminal (iTerm2, Terminal.app, etc.); on terminals without truecolor it falls back to the xterm-256 palette automatically (force either way with --color truecolor|256).

Every run prints the exact flags to reproduce it, so when --random rolls a look you like you can pin it or tweak one knob:

glowdrift mode=vortices (rolled 17 knobs)
  reproduce: glowdrift --seed 12 --mode vortices --flow-scale 1.7 ...

Playing with the flow

Two independent axes drive the movement: the motion model (how a particle moves) and the direction field (which way it points). Mixing them is where the variety comes from, e.g. glowdrift --motion orbit --mode ripple.

--motion (how particles move):

motion	movement
flow	smooth advection along the field (drifting strands)
curl	divergence-free turbulence, coils into eddies, never bunches
inertial	momentum: comet-like sweeps that bank and overshoot
orbit	gravity toward drifting attractors, orbiting swirls + slingshots
spiral	differential rotation around a center (galaxy arms)
harmonograph	parametric lissajous loops (a cloud of nested curves)
jitter	brownian drift, a grainy diffuse cloud
levy	heavy-tailed flight: small drifts with rare long leaps, bursty and clustered
pendulum	each particle a chaotic double pendulum, swinging looping arcs

--mode (the direction field, used by flow / inertial / jitter / levy): waves (combed streams), vortices (whirlpools), ripple (concentric petals), spin (a breathing pinwheel), saddle (a rotating hyperbolic push/pull).

Other flow knobs:

knob	what it does
--flow-bias DEG	global flow direction in degrees (0=right, 90=down, 270=up)
--swirl 0..1	0 = everything flows toward the bias direction, 1 = full field swirl
--flow-scale	swirl zoom (cycles across the canvas)
--flow-drift	how fast the field evolves over time
--flow-spread	angle variation (higher = more curl / chaos)

Color / shape knobs:

knob	what it does
--hue-center DEG / --hue-range DEG	limit colors to a slice of the wheel (range 360 = full rainbow)
--colors N	quantize to N discrete colors (0 = continuous)
--edge 0..1	shape edge: low = soft wispy strands, high = hard crisp strokes

Other look knobs: --speed, --decay (trail length), --exposure (bloom), --saturation, --hue-spread, --hue-drift, --hue-jitter, --glow-radius, --glow-softness, --density (lower = more particles). Run glowdrift --help for every default and random range. --random rolls all of them from --seed; any knob you pass explicitly is kept fixed while the rest are randomized.

Browse a bunch of looks at once

glowdrift --contact 12 --out /tmp/sheet   # grid of 12 random variants, labeled by seed

Eyeball the grid, then run glowdrift --random --seed N for the one you like.

How it looks the way it does

• Organic motion comes from a flow field built from summed drifting sinusoids, so the swirls evolve continuously and never repeat.
• Rainbow is a diagonal hue gradient across the canvas that slowly rotates over time, so the whole wheel is on screen at once and drifts.
• Glow is additive: each particle stamps a soft radial kernel, the field decays ~10% per frame for trails, and a hue-preserving 1 - e^(-x) tone-map gives the bloom rolloff while keeping the background black. Mapping the brightest channel and scaling the others by the same factor keeps dense overlaps saturated instead of washing them to white.

Look without a terminal

Render a warmed-up frame to a PNG (handy for tuning):

glowdrift --render 200 --out /tmp/gd --width 160 --height 48

Options

flag	default	meaning
--fps	30	frame-rate cap
--seed	1	changes the composition
--render N	-	headless: simulate N frames, write a PNG, exit
--out	/tmp/glowdrift	PNG path prefix for --render
--width / --height	160 / 48	canvas size (cols/rows) for --render

License

MIT, see LICENSE. Copyright (c) 2026 E. T. Carter · dnvsfn.