Core demo craft

A demo is a real-time audiovisual performance generated by the computer. It follows a designed sequence from beginning to end. You watch it rather than play it—and Escape exits.

A demo moves by elapsed time, not by counting frames. That is why the same production looks the same on a fast machine and a slow one. Every effect here is drawn from the seconds that have passed since playback started.

Most classic effects are repeating waves. Frequency is how tightly the wave repeats, amplitude is how strong it is, and phase is where it starts — moving the phase over time is what makes a still pattern move.

An effect is a small set of rules drawn many times per second. Starfield is three numbers per star, projected through a perspective divide. Change one rule and the whole look changes.

Demosceners keep the variations they like and reuse them later. In SceneStart that is the local project file: save the settings you are happy with, and open them again in any session.

Two simple effects together read as one richer scene: geometry plus typography, or depth plus colour. Combining is mostly about restraint — one idea should stay dominant.

Sync means motion changes on musical events: a beat, a bar, a section. Even without audio you can design in bars — decide how long a section lasts, then change something exactly when it ends.

A production is a sequence, not a slideshow of effects. Opening, escalation, climax and ending give the audience somewhere to arrive. Plan that arc before adding more effects.

A release is a package someone else can run: an obvious file, run instructions, credits, and honest documentation of anything you did not make yourself.