The Clip Brushes are different from any other brushes as their operation is always perpendicular to the canvas. These brushes are similar to how the Eraser tool cuts away pixols on the canvas, except that they are used to cut away areas of your model and slice its borders. These Clip brushes do not change the topology of your model; they only push the polygons based on the stroke you apply to your model.
Since the clip Brushes use open and closed curves, it is important to know which side the clipped polygons will be pushed to. For this purpose, the curves have a shadow on one side and polygons will be pushed in the direction of the shadow. If you create your stroke in the wrong direction, just press the ALT key to tell ZBrush that you want to push the polygons in the other direction.
The clip brushes respect masking. If you want to protect an area from being pushed, simply paint a mask on it. Don’t forget to check your model for unprotected areas as the clip brushes operate through the whole depth of the model relative to the curve.
When tapping the ALT key once with the ClipCurve brush you will create a curved line that can be changed in direction every time ALT is clicked. If you double-tap the ALT key when using the ClipCurve brush, the change in line direction will be a sharp angle rather than a smooth curve.
When holding the ALT key while using the Circle or Rectangle Clip brush, ZBrush will cut away all of the mesh that is inside the drawn circle or rectangle. Understand that if you hold the ALT key and the cross indicator is over any part of the mesh there will be a result of geometry being pushed out.
The clip brushes all share the same behaviors; only the Stroke type makes them different.
Clip brushes additional features
By pressing Ctrl+Spacebar while using a Clip brush, a pop-up window will appear offering two options:
- Brush Radius: When enabled, the polygons will be partially pushed to the line depending upon the brush size and the distance of the mesh from the camera.
- By Polygroup: When enabled, a polygroup will be created based on the pushed geometry included in the circle or rectangle stroke.
Brush Radius and By Polygroups are also located in the Transform palette.
Center position for Circle and rectangle Clip Brushes
When drawing a Circle or Rectangle stroke, a small cross appears in the middle of the shape. When the cross is outside of the mesh, the polygons are cut to the edge of the circle or rectangle to create a notch in your model. When the indicator is inside the mesh, polygons will be pushed out which results in an expansion of geometry rather than a cut.
Note: When pressing ALT while the indicator is inside the mesh, the stroke switches from white to black and the polygons located inside the stroke are pushed perpendicular to the screen, in both directions.
If you start to create a stroke and need to move it, hold the spacebar and move your cursor; the stroke will move. Release the spacebar to continue or finish the stroke.
Selecting and using Clip Brushes
As with the Smooth brushes, the Clip brushes are activated by hotkey. When selecting a Clip brush in the Brush palette, it will automatically be assigned to a specific hotkey: Ctrl+Shift.
When using a normal brush, press Ctrl+Shift to activate the last selected Clip brush. Release Ctrl+Shift to return to using the normal brush.
Selecting another Clip brush will replace the previously selected one without changing the active normal brush.
For the different types of Clip brush see: