When we are sculpting it can be very helpful to isolate parts of our mesh to organize our work. Face sets is a great feature that allow us to do just that.
To use face sets follow these steps.
This is just the tip of the iceberg. Let's continue to explore face sets in its entirety.
Fase sets is a sculpt mode feature that allows us to group geometry. We can quickly hide and show geometry based on these sets.
We can also perform a few other tasks on the mesh like creating an extrusion from a face set and smoothing the geometry in a face set using the edit face set brush.
There are four sculpt brushes related to face sets in Blender. These are:
There is also a menu in the 3D viewport header labeled face sets as well as a pie menu that we can access by pressing W.
There are also a couple of auto masking features available for all brushes that we will also cover.
Note that there is also something called face maps in Blender. These are different from face sets but the functionality has similarities. Face maps is an edit mode feature that we can access from the object data tab in the properties panel, and it is a feature that allows us to store and retrieve face selections.
Let's continue to explore face sets.
First change the 3D viewport to sculpt mode or go to the sculpting workspace.
You can find the draw face set brush from the left side toolbar.
To use it, select it and click and drag across your object. For every new stroke you make Blender uses a new color. Each color is its own face set.
We can also expand a face set instead of drawing a new one with every stroke. Hover your mouse cursor over an existing face set, hold CTRL, left click and drag to draw.
To subtract mesh from a face set, you do the same but instead of hovering your cursor over a face set you hover it over geometry that isn't part of a face set or outside your object altogether.
Now when we have face sets and some basic control over them, we can start to hide geometry. To hide everything except a face set, hover the mouse over the face set and press H. All your other geometry will be hidden. Press H again to unhide.
This way we can use H to toggle hide and show a mesh. For as long as we hover the face set or empty space in our 3D scene, we can continue this toggle. But if we move our cursor over another part of the geometry, that part will be shown while all other geometry is toggled between shown and hidden instead.
When we have drawn multiple face sets with the draw face sets brush, we can also use Shift+H to hide the mesh we are hovering instead of everything but the mesh we are hovering.
If we have multiple face sets, this may make more sense, since we can hover multiple ones and hiding the one after another until we have the face sets left that we want to work with.
Note here that the mesh that isn't marked as a face set is still working as a face set. So if you have created a face set, you technically have two face sets, the mesh that is painted and the mesh that isn't.
For Blender, there is no difference between them.
We have a couple of other useful ways of creating face sets. If we go to the face sets menu in the header of the 3D viewport, we will find multiple operations regarding face sets. For now, I want to bring your attention to "face set from masked" and "face set from edit mode selection".
These two options allow us to either use the mask created with our mask brush in sculpt mode if you are used to using that tool, or use the current edit mode selection. "Face set from masked" can also be accessed through the W pie menu.
Related content: How selecting works in Blender
Now when we have the basics down, let's look a bit deeper into each tool available to work with face sets.
We use the draw face set brush to draw new face sets with every stroke. or by holding CTRL to expand or erase from them depending on our mouse cursor position when the stroke starts.
We then use H or Shift+H to hide or unhide face sets.
We can access the draw face sets brush settings in three ways. Once the brush is selected from the left side toolbar, we can use the header bar in the 3D viewport to change the brush settings.
We can also access these tools through the right-side panel called the N-panel. Toggled with the N hotkey, or in the active tools and workspace settings found in the topmost tab in the properties panel.
In all of these places we have the usual brush tools, such as strength and radius.
Apart from these, there are a few settings that can be interesting for the draw face set brush.
In the advanced subsection, from the header, you find these by opening the brush menu, there are a few toggles we will cover.
Let's start with topology. This will make it so that a single brush stroke won't traverse between meshes that arent physically connected. For example, using the monkey object in Blender and drawing a face set starting at the nose won't cover the eyes with the face set since the eyes are separate from the main body mesh.
If we check face sets we will only be able to paint inside the face set we started our brush stroke in. This will allow us to maintain already established face set borders.
The front face only setting will make it so that faces won't be added to a face set if you can't see their front side in the viewport while painting them. You can try this with the monkey object as well. You can paint the ears with a face set with or without this setting and see how the backside is also added to the face set if front face only isn't checked.
The head of the monkey object is too thick for this to have any paint through effect, so it only affect thinner geometry.
Note also that you can hold Shift and draw over an edge of a face set to smooth it. This also changes the underlying geometry. This is useful when we sculpt if we don't care about the underlying topology during sculpting and that is most often the case during the sculpting process.
You can also bring the smoothing back to its jagged state by setting auto-smooth in the brush settings to 1 and paint over the edges again. Note though that geometry won't go back to its original position. It will also get flattened around the area.
With a strength set too high on your brush this can quickly destroy your mesh. With a strength of 1 the mesh will render completely useless with just a single brush stroke. Use Ctrl+Z to undo if this happens.
To remove part of a face set, use the draw face brush, start from outside the mask, hold ctrl and draw over the mask to replace it with another mask or remove it if you started on mesh that isn't assigned a face mask.
To clear all face sets, go to face sets->face set from visible when everything is visible. This will set everything to one face set. You can also access this feature from the W pie menu
If you remember from earlier, we said that when we create a face set, we actually have two. Everything that isn't painted as a face set also acts as a face set. Face set from visible, makes everything a single face set again, removing all face sets that we created ourselves.
The terms used here can be a bit confusing, but that is how it works to clear face sets.
Initializing face sets means that we create starting face sets based on some criteria.
Go to face sets->Initialize face sets submenu to create face sets. These are our available options.
Let's start with the easy ones. UV seams, edge creases, bevel weight and sharp edges are all edge markings that you can read about here:
Related content: Blender edge marking guide
We can use any of these edge markings to create face sets from their boundaries.
Next, face maps and materials are also similar. They will set each area covered by a certain material of face set to it's own face set.
That leaves us with loose parts, normals and face set boundaries. Loose parts will create a face set for each loose part of the geometry. Face set boundaries will work the same with the exception that it will preserve existing face sets.
For normals, I am not sure exactly how it works, but it seems like it is creating face set borders where there are very sharp edges.
To expand a face set you can hover your mouse over the face set and press Ctrl+W. To shrink it, hold Alt+Ctrl+W while hovering the face set with your mouse.
You can find these operations in the face sets menu and we can use the Edit face set brush.
Find the edit face set brush in the left and side tool panel. In the header select the grow face set and click the face set you want to expand.
There is also a shrink face set mode to shrink face sets in size.
We can use a face set to extract a new mesh from it. Go to face set->Extract face set. An eye dropper tool will become active. Click on the face set you want to make into a mesh.
A new mesh is created from the faces, and they will be made up of a new object sharing the same origin as the original object.
You will also be taken to object mode and the new mesh will have a solidify modifier added to it.
Let's briefly also cover the other brushes related to face sets.
We have already looked into the edit face set brush with the shrink and expand modes. There is also a delete mode where we can remove geometry that belongs to a certain face set just by clicking on it.
We also have the fair position and tangent options. There are two ways of smoothing the mesh belonging to the face set.
Next we have the box face set brush. It creates a box shaped face set that goes through all mesh. So it covers both the front and back side. It can be very useful if you have something like an arm or a hand that you want to contain within a face set to work on separately.
The lasso face set is similar to box face set. Instead of creating a box, you can draw a shape freely and create a face set out of it. You can find the lasso select brush by hovering the box face set brush in the left side tool panel, long click it and a menu will appear revealing the lasso select tool.
All brushes in Blender have a couple of settings related to face sets that we can use. We can find these in the options section. Either to the far right in the viewport header or in the tools tab we can find an options section in either the properties panel or the N-panel.
If you look under auto-masking you will find "face sets" and "face sets boundary".
If we check face set, a stroke with our brush that starts in one face set cannot traverse over into another face set.
We can also lock all vertices that sit at a border between face sets so that they can't be moved by brush strokes if we check "face sets boundary".
We can use both of these settings at the same time or just one of them to get the desired functionality.
In this article we have taken a deep dive into the world of face sets. A tool that is a bit scattered between menus, pie menus and brushes. It is a useful tool set to isolate parts of our geometry and and work at one piece at a time without having to worry about messing up another part in the process.
Thanks for your time.
