Here entire mesh is one subtool with multiple polygroups. It was exported to Zbrush via Goz from Maya. Basically each polygroup represents different object. (Their vertice aren't merged).
Now fun part. When doing booleans Zbrush produced a new subtool with booleaned components and connected those 2 and merged their vertice.
Now after I do polygroups again as you can see the screw which was green before and the part below it which was blue got merged into one. Doing polygroups again resulted in one purple group.
Now my question is basically this.
Is it possible to somehow tell Zbrush to not union components with different polygroup assigned?
Replies
If you don't want certain groups to be be part of that operation, first split them off into new subtools and then use the new Start Groups (the arrows) so that these subtools are not part of any other grouping. The Boolean process will generate as many SubTools as you have defined Start Groups, so each group won't affect the others.
You can read more about Start Groups in the ZBrush4_R8_whats_new.pdf documentation (page 30).