Advanced masks

Mesh selectors, painted corrections, nested mask groups and custom shader graphs for editable coverage.

On this page 4 sections

A layer's coverage is an ordered stack of independent sources. Painted images, generators, mesh selectors, scene fields, strokes and nested groups each retain their own blend operation, strength, invert and black/white levels. Filters transform the coverage accumulated before them.

Inspect and paint a correction

Select the intended layer, then its mask icon. The Inspector names the target.
Use View Mask to inspect grayscale coverage. Refresh the snapshot if it is out of date.
Click Add Paint to Mask to add a separate painted correction over the existing effects.
Follow the Inspector's instruction: paint black to remove coverage for Multiply, or white to add coverage for Add. Paint Mask starts the native brush; Finish ends it.
Choose Back to Material to restore the composed appearance.

Normal replaces coverage according to strength; Multiply restricts it; Add accumulates it; Lighten (Max) combines covered areas and Darken (Min) keeps their intersection. Smart masks add editable presets to this same stack.

Mesh masks

Choose Add Mask › Add Mesh Mask, then set Select By. Coverage is rasterized through the assigned faces' render UVs. Combine a Collection mask with Rust, for example, to restrict corrosion to objects in your Screws collection.

Select By	Coverage
Object	Assigned faces of one object.
Collection	Assigned objects in the collection, optionally including child collections.
Material	Faces using a material now or before the texture set replaced the original slot.
Vertex Group	Interpolated vertex weights from a named group.
Face Set	One sculpt face set.
Face Selection	The current selected faces of assigned meshes.
UV Island	Islands containing selected faces, or one island by index.
Normal Direction	Faces within an angle of a direction, with a soft falloff.
Geometry Attribute	A named point, face or corner attribute: scalar, integer, boolean or vector length.

Collection membership, materials, weights and geometry changes update the mask without a bake. Face-selection changes made in object mode may need entering and leaving Edit Mode to trigger an update. Portable materials retain selector names and attempt to relink them in the destination scene.

Nested mask groups

Add Mask Group creates a nested stack. Members combine first, then the group's result combines with its parent using the group's own operation, levels, strength and invert. For example, group Curvature × Noise followed by Levels, then multiply that group by a painted mask.

Adding while a group or member is selected inserts into that group. The list controls move entries into the group above, lift them out, move a group with its members, or dissolve the group in place. Disabling a group disables its entire contents. Anchors can publish partial coverage from inside groups.

Custom shader graphs

Add Custom Graph creates a starter shader node group with UV input and Coverage output. UV/Vector, Position and Normal inputs are connected when present; the first output provides coverage. Editing the group updates the Shader Native viewport. Export and CPU snapshots bake it with Cycles over the assigned meshes and refresh that bake when the group changes.

Related workflows: anchors and graph connections, live scene fields and seam-aware filters. References: mesh masks and mask architecture.