How to do weight paint on one side, even with mirror modifier I would like to rig a mesh (for example Susanne, the monkey) manually, using 3 bones, and this object uses a mirror modifier and a subsurf modifier. The left bone has 0 vertices assigned yet and the right bone has a few vertices assigned. Because of the mirror modifier, when I weight paint the right side, the left side will also be painted, which means that both sides are controlled by the right bone. How can I solve that only the right side is weight painted with mirror modifier, without applying the mirror modifier?




But when I first select the monkey, then the armature, press CtrlP, automatic weights, then only one side is weight painted, even with mirror modifier




How can I solve that only the right side is weight painted with mirror modifier, without applying the mirror modifier? I know this is a duplicated question of Unmirror Weight Paint, but I don't want to apply the mirror modifier, because I may want to edit the mesh later and the mirror modifier is then convenient. Thanks :)
The vertex weights checkbox on the mirror modifier will make it mirror weights to 'mirror' groups if they exist. E.g. weights in Group.L will be mirrored to Group.R if Group.R exists, otherwise those mirrored weights will be assigned to Group.L

It always surprises me how few people seem aware of this behaviour.