I continue to share the library of scripts that I have been collecting over fifteen years of work in the industry.

checkerPolySelect

Briefly: checkerPolySelect takes the current polygon selection in Editable Poly or Edit Poly and selects every other polygon in a chessboard pattern, traversing the mesh through edges. It is convenient when working with regular meshes, when you need to quickly thin out the selection or prepare alternating groups of polygons for further operations.

Convenient when you need to select "every other" polygon.

Installation:
1. Drag the .ms file directly into the viewport or run it via Scripting > Run Script.
2. To have the script run automatically on startup, copy the file to the scripts/startup folder.
3. To assign it to a button or hotkey: open Customize > Customize User Interface, find the MyTools category, there will be the CheckerPolySelect macro — drag it to the toolbar or assign any hotkey.

Functionality:

The script works in polygon mode for objects of type Editable Poly and with the Edit Poly modifier.

If any polygons are selected at the time of execution, the script only works within that selection. If nothing is selected, it captures all polygons of the object.

Disconnected islands of geometry are processed independently: a separate BFS is run for each connected component, groups are synchronized by a stable rule (the minimum index of the starting polygon), so the chessboard pattern does not "shift" at the seams of the islands.

If the topology contains odd cycles (triangles, pentagons, and similar rings), a clean two-color coloring is not possible in those places. The script detects a conflict during BFS, does not interrupt and does not produce garbage selection — instead, it outputs a warning in the status bar and continues a locally correct traversal on the remaining geometry.

Compatibility: 3ds Max 2016 and higher.