The Multi/Sub-Object material lets you assign different materials at the sub-object level of your geometry. You create a multi-material, assign it to an object, and then use the Mesh Select modifier to select faces and choose which of the sub-materials in the multi-material are assigned to the selected faces.
Figure mapped using a Multi/Sub-Object material
If the object is an editable mesh or editable poly, you can drag and drop materials to different selections of faces, building a Multi/Sub-Object material on the fly. See Drag and Drop Sub-Object Material Assignment.
You can also create a new Multi/Sub-Object material by dragging to faces selected with the Edit Mesh modifier.
Sub-material IDs do not depend on the order of the list, and you can enter new ID values.
The Material Editor Make Unique function lets you make an instanced sub-material into a unique copy.
At the Multi/Sub-Object material level, the sample slot's sample object shows a patchwork of the sub-materials. When you edit a sub-material, the sample slot display depends on the setting of the Simple Multi Display Below Top Level toggle in the Material Editor Options dialog.
Here are some usage tips with regards to mesh editing and managing sub-materials.
To create a Multi/Sub-Object material, do one of the following:
3ds Max opens a Replace Map dialog. This dialog asks whether you want to discard the original material in the sample slot, or retain it as a sub-material.
The controls for a Multi/Sub-Object material are essentially a list of the sub-materials it contains.
To assign a sub-material, do one of the following:
The parameters for the sub-material appear. By default, a sub-material is a Standard material with Blinn shading.
To make one of the sub-materials a solid color:
In the Color Selector, choose a color.
The color swatches for sub-materials are shortcuts. They assign the color you choose to the sub-material's Diffuse component.
To assign one of the sub-materials to a sub-object selection:
The viewport updates to show the sub-material assigned to the selected faces.
The material ID values in the Multi/Sub-Object material and the material ID numbers in the Select Face rollout correspond. If you set the ID to a number that doesn't correspond to a material contained in the Multi/Sub-Object material, the faces render as black.
To add a new sub-material:
A new sub-material is added to the end of the list. By default, the new sub-material's ID number is one greater than the highest material ID already in use.
To remove a sub-material:
The small sample sphere is surrounded by a black and white border to show the sub-material is selected.
If the list of sub-materials is longer than the rollout will hold, you can use the scroll bar at the right to display other parts of the list.
The sub-material is removed.
Deleting a sub-material is an undoable operation.
Reducing the number of sub-materials removes sub-materials from the end of the list. You can undo Set Number when you have used it to delete materials.
These buttons appear above three of the columns in the sub-materials list.
Each sub-material has a single entry in this list. The rollout displays up to 10 sub-materials at a time. If the Multi/Sub-Object material contains more than 10 sub-materials, you can scroll the list using the scrollbar at the right.
Each sub-material in the list has the following controls:
When the Multi/Sub-Object material is applied to an object, faces in the object assigned the same material ID number render with this sub-material.
You can click Sort by ID to sort the sub-material list by this value, from lowest to highest.
By default, each sub-material is a Standard material with Blinn shading.