A mask is an area of your model that is ‘shielded’ from sculpting, painting, etc. Masks only apply when in 3D Edit mode. (See ZBrush Modes.)
Note: The sections below talk about manipulating masks directly as you model. However, the Tool:Masking submenu contains quite a few controls that can be used to generate masks automatically, affect properties of masks and mask drawing, etc.
Masked areas are not simply on/off. Instead, they can be unmasked, partially masked to some degree, or fully masked. The effect that operations such as sculpting have on masked areas of a model depends on the intensity of the mask at each point.
You can paint masks on your object directly by holding down the Ctl key while painting on the model. (The stroke must begin on the model.) By default, masked areas show up as dark patches on the model. The following figure illustrates this:
Drag Rectangles Across Part of Your Object
Hold down the Ctrl key, click on the canvas outside your object (not too close, either), and drag a rectangle across part of your object. You can see the results below. Note: You need to start the drag outside the object, but you don’t need to end it outside the object.
If an alpha is selected in the Alpha palette then this is used to define the masked area.
Lasso Parts of an Object to Mask
You can select the Lasso Mask brush by holding Ctrl and clicking on the large Brush thumbnail.
Hold down the Ctl key, click on the canvas outside of your model. Drag out a lasso selection.
Invert an Existing Mask
To invert an existing mask, hold down the Ctl key and click on the canvas outside the model.
Note: A convenient way to mask an entire object is to invert the mask while the object is completely unmasked.
Blur a Mask
Ctl-click on a masked area to blur the mask. This will ‘spread the mask out’ further across the object, while decreasing its intensity.
Unmask an Area
You can ‘unpaint’ a previously masked area, by holding down Ctl+Alt and painting onto the model.
In this figure, the inverted mask has been taken from the previous figure, and the ‘border’ of the model has been unmasked using Ctl+Alt-paint.
Note: If you don’t want to remember the unmasking key combination, you can also unmask an area by inverting the current mask, painting a mask onto the area you want to unmask, and then inverting the mask again.
Clear a Mask
Hold down the Ctl key and drag on the canvas outside the model. Any visible amount of dragging will do.
Create a Mask Using Topology
This masking method is discussed more thoroughly in the Transpose page, which is where the topological masking is functional. Basically, when in transpose mode, you can Ctrl-drag along the surface of a model, to have a mask dragged out across the surface, following the topology of the model. On models with typical topology, this gives an extremely fast, easy way to mask out limbs, tentacles, branches, and other extrusions.
Quick One-Touch Masking of Polygroups
Masking out particular parts of your models can be a tedious process – especially when it’s a complex model. However, if your model has PolyGroups this can become a very quick and easy process. Simply press W or click the Move button and then Ctrl+Shift+click on any PolyGroup. All other groups will immediately be masked.