An RGB Matrix function projects patterns and text onto a grid of RGB fixture heads, scriptable in JavaScript

The RGB Matrix renders pixel graphics onto a Fixture Group (a user-defined grid of fixture heads). Built-in patterns: Plain Color, Animated Text, Image (static/horizontal/vertical/animation modes), and Audio Spectrum (audio-reactive bars). Each pattern has configurable colors, speed, run order, and direction. Blend Mode layers multiple RGB Matrices. Custom patterns are ECMAScript/JavaScript scripts implementing rgbMapStepCount and rgbMap functions. This makes pixel-mapped LED walls programmable with the same language as web development.

Examples

An Audio Spectrum RGB Matrix on a 16×8 LED wall shows frequency bars reacting to a kick drum. A custom JS script can render a bouncing ball animation.

Assessment

Write the skeleton of an RGB Script that lights one column at a time from left to right. What must rgbMapStepCount return for a 12×8 matrix?