Cutters and Brush Groups
Cutters
A cutter is a brush with Subtractive enabled. It is not rendered in the game. Instead, it carves its volume out of every brush it overlaps. Doorways, windows and niches are cutters. They stay live: move or resize a cutter and the opening follows.
- Select brushes and press
Alt+C(Make Cutter in the panel's CSG section) to turn them into cutters, or back into solid brushes. - In the editor a cutter shows as a translucent orange volume. A cutter that is not convex shows red and cuts nothing, and the Health section lists it. Decompose splits it into convex cutters.
- The brushes being cut can have any closed shape.
- Faces created by a cut get their own ids, so you can give a doorway's jambs a different material than the wall.
- Cutters only cut brushes, not meshes or other components.
CSG Commands
All of these work on the selected brushes and are single undo steps.
| Command | Description |
|---|---|
| Make Cutter | Toggles the brushes between solid and cutter. |
| Carve | Bakes the selected cutters into the brushes they overlap and deletes the cutters. |
| Hollow | Turns each brush into walls of its Thickness, keeping its outside shape. |
| Union | Merges the brushes into the first one. |
| Clip | Cuts the brushes with a plane, see Editing Brushes. |
| Decompose | Splits non-convex cutters into convex pieces. |
| Group Brushes | Wraps the selection in a new brush group (Ctrl+Shift+G). |
Brush Groups
A game object with a Brush Group component groups the brushes below it.
| Property | Description |
|---|---|
| Isolate Cutters | Cutters inside the group only cut brushes inside the group, and cutters outside of it do not cut into the group. Enabled by default. |
| Merge On Export | Static brushes of the group are merged into one mesh per material when the scene is exported. Enabled by default. |
Use groups to organise a level into rooms or buildings, to keep a cutter from reaching into the next building, and to control how brushes are merged at export. Brushes drawn while a group or anything inside it is selected go into that group.