How to Use a Vertex Group with Mask Modifier in Blender

Using a vertex group with the Mask modifier in Blender allows you to non-destructively hide or reveal specific parts of a 3D mesh. By assigning weight values to vertices and referencing that group inside the modifier, you can dynamically control geometry visibility for animation, rigging, or clean viewport management. This guide provides a direct, step-by-step process to set up and configure this feature.

Step 1: Create a Vertex Group

  1. Select your 3D object in the viewport.
  2. Go to the Object Data Properties tab (represented by a green triangle icon in the right-hand panel).
  3. Expand the Vertex Groups section and click the + (plus) button to create a new group.
  4. Double-click the newly created group to rename it for clarity (e.g., "MaskGroup").

Step 2: Assign Vertices to the Group

  1. Switch to Edit Mode by pressing Tab.
  2. Select the vertices you want to affect.
  3. In the Vertex Groups panel, set the Weight slider to 1.000 (or your desired weight).
  4. Click the Assign button underneath the vertex group list.
  5. (Optional) You can also switch to Weight Paint Mode to paint the weights directly onto your mesh.

Step 3: Add and Apply the Mask Modifier

  1. Switch back to Object Mode (Tab).
  2. Go to the Modifier Properties tab (represented by a blue wrench icon).
  3. Click Add Modifier and select Mask from the Generate category.
  4. In the Mask modifier settings, locate the Vertex Group field.
  5. Click the field and select the vertex group you created in Step 1.

Step 4: Adjust the Mask Settings

  • Invert Visibility: By default, the Mask modifier keeps only the vertices assigned to the vertex group. To hide the assigned vertices and show everything else, click the Invert icon (two opposing arrows) next to the Vertex Group selection box.
  • Threshold: Adjust the Threshold value if you used weight painting with non-binary values (weights between 0.0 and 1.0). Vertices with weights below this threshold will be hidden.