Use -1 in a WLED ledmap to mark absent pixels in non-rectangular shapes

When an LED layout has irregular gaps — for example a figure-eight shape with empty corners — those positions in the ledmap.json array should be set to -1. WLED renders those positions as blank (off) pixels, enabling non-rectangular 2-D surfaces to be described accurately. This is essential for shapes like spirals, letters, or double-infinity panels where not every grid cell has an LED.

Examples

A 9×5 grid encoding a double ∞ shape includes many -1 entries for the corner cells that have no physical LED: {"map":[-1,-1,14,-1,12,...], "width":9, "height":5}.

Assessment

Explain why a 5×5 grid mapping a circular LED ring would need -1 entries, and identify which cells would carry them.