by Garrett Mace (macetech.com), inspired by Mark Kriegsman
Set the maximum x and y dimensions, layout style (how the LEDs are actually wired), and click Rebuild.
Then click LEDs to edit the shape of the array by enabling and disabling pixels. The code is updated in realtime.
Copy the resulting function and paste into your code.
The function will map ordinary X-Y coordinates to the irregular array, preserving pixels that land in gaps.