PolyGroups (which are groups of polygons identified by a specific color) are an essential part of the creation process with ZModeler.
ZModeler has an extended toolset of functions to create and manipulate PolyGroups, such as using them as a Target so that an Action will affect all polygons belonging to the same PolyGroup, no matter where they appear in the mesh. PolyGroups can also be modified in the in the Tool >> Polygroups sub-palette.
Propagation of PolyGroups
The current PolyGroup remain the same until you decide to assign a new PolyGroup after an Action. Several Targets specifically use the PolyGroups while most Actions will either create or propagate PolyGroups. Depending on your needs, you can use the PolyGroup Action to create new PolyGroups before applying another Action.
An example of this: Using the Extrusion Action will maintain the existing PolyGroup for the top part of the extrusion while creating a new PolyGroup for the sides. Continuing this Action elsewhere on the model will continue produce identical PolyGroups unless you instruct ZBrush otherwise.
When modeling there may be times when no specific Target fits the selection you are looking for. Or perhaps you may simply want to extend an existing Target with extra polygons from another location. For this purpose, ZModeler has an integrated Temporary PolyGroup which is always displayed as white.
To apply the Temporary PolyGroup, you must be working with a polygon Action. If so, simply Alt+click the desired polygons. These polygons will turn white to indicate that they are part of the Temporary PolyGroup. You can also click and drag to paint this Temporary PolyGroup.
Alt+clicking a white polygon will remove it from the Temporary PolyGroup selection.
You are free to continue editing this Temporary PolyGroup until you execute an Action.
The Temporary PolyGroup always adds to the current Target. As an example, if you are selecting an Extrude Action with a Polyloop Target and create a Temporary PolyGroup out of polygons not belonging to the poly loop you are looking for, the Action will extrude both the poly loop itself and any polygons belonging to the Temporary PolyGroup.
Changing of PolyGroups During an Action
While editing your model, it may happen that you would need a different PolyGroup from what is being created by the Action. While still applying the Action, simply tap the Alt key once to change the PolyGroup to another one.
The actual color of a PolyGroup is irrelevant to any Actions or Targets but sometimes PolyGroup colors might be too similar for you to be able to easily tell the groups apart. If you don’t like the color that ZBrush gives you, tap Alt again and repeat until you find something that you’re satisfied with.
Not all Actions permit you to use Alt to change the PolyGroup color. This is because they use the Alt key as a modifier.
Be careful to not tap the Alt key until after you have started executing the Action. Otherwise you could end up changing the Target instead or even add polygons to the Temporary PolyGroup.
Copying an Existing PolyGroup
The Temporary PolyGroup is useful for one-off selections but you will sometimes want to keep coming back to the same Targeted polygons. In this case, you can apply an existing PolyGroup to another location. With the PolyGroup Action, it is possible to pick a PolyGroup identifier and color, then copy and store it for the next Action.
To do this, follow these steps:
- Select the PolyGroup Action
- Select the A Single Poly Target
- Hover over a polygon belonging to the desired PolyGroup.
- While clicking and holding on this polygon, press (or tap) the Shift key. ZBrush will copy the clicked polygon’s PolyGroup. Release the click.
- Now click on another polygon to paste the PolyGroup.
You can do this on multiple locations. Try it also with other Targets, like Polyloop to apply the same strips of PolyGroups on multiple polygons.