Dot flag
A grid of dots rippling like a flag in the wind, often in the group's logo colours — a classic oldskool effect on the Amiga and C64.
The dots sit in a two-dimensional grid, and each one is displaced by sine waves that depend on its row, its column and time. Projected into 3D, that reads as billowing cloth. The sine tables are precalculated, so the real cost is just plotting the dots fast enough — on the C64 that usually decided how big the flag could get.
It was a favourite in intros and cracktros, where it could carry a logo or a national flag for the price of a few hundred dots. Filled-polygon versions came later, but the dotted original has its own charm: it looks more like stars than fabric.