Overview
The demoscene topic renders classic Amiga and IBM PC demoscene effects directly in your terminal.
It uses the Unicode upper half block character ▀ (U+2580) with 24-bit ANSI colour codes
to double the effective pixel density: the foreground colour paints the top half of each character cell
and the background colour paints the bottom half, giving two pixel rows per terminal row.
All effects animate in real time, running for a configurable number of frames at ~20 fps before returning to the shell. Press Ctrl+C at any time to stop early.
kefrens
Renders a Kefrens-style effect — multiple vertical colour bars that scroll across the screen following independent sine wave paths. Each bar has a distinct hue and a soft brightness falloff from its centre, giving the classic glowing-bars look of the Amiga demo era.
The effect fills the full terminal window and runs until the requested frame count is reached. Eight bars covering the rainbow spectrum are rendered simultaneously, each moving at a different phase so they weave across and through one another.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render before exiting |
boing
Renders the classic Amiga Boing Ball — a red-and-white checkered sphere bouncing around a grey grid background. The checkerboard pattern rotates as the ball moves, giving the impression of spin. This effect was famously used to demonstrate the graphical capabilities of the original Amiga 1000 in 1984.
The ball bounces off all four walls and its checkerboard pattern rotates continuously. The grey grid background echoes the original demo's distinctive aesthetic.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render before exiting |
plasma
Renders the classic IBM PC plasma — several sine fields are summed per pixel and looked up in a smoothly cycling rainbow palette.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render before exiting |
fire
Renders the classic IBM PC fire effect — random embers on the bottom row are averaged upward each frame and cooled, mapped through a black-red-yellow-white palette.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render before exiting |
copper
Renders classic Amiga copper bars — shaded horizontal raster bars with metallic highlights that weave in front of and behind each other.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render before exiting |
showcase
Plays every demoscene effect in sequence (boing, plasma, kefrens, fire, copper), alternating Amiga and IBM PC classics.
| Option | Required | Default | Description |
|---|---|---|---|
--frames | No | 200 | Number of animation frames to render for each effect |
Command Reference
| Command | Description |
|---|---|
pbtk demoscene kefrens [--frames N] |
Animate Kefrens-style sine wave colour bars across the terminal |
pbtk demoscene boing [--frames N] |
Animate the classic Amiga Boing Ball bouncing on a grey grid |
pbtk demoscene plasma [--frames N] |
Animate the IBM PC sine-field plasma |
pbtk demoscene fire [--frames N] |
Animate the IBM PC fire effect |
pbtk demoscene copper [--frames N] |
Animate Amiga copper raster bars |
pbtk demoscene showcase [--frames N] |
Play all demoscene effects in sequence |