Apply materials

There are several ways to apply materials to geometric objects created in or modified by Bifrost. The basic node for assigning materials is assign_material.

It is important to note that Bifrost does not perform any rendering itself — materials are simply sub-objects of geometry with specially-named properties that can be read and used for display in the viewport, or for rendering by compatible renderers such as Arnold.

Type of material

There are two basic types of material:

• Referenced materials are references to a material that exists in the host scene. Objects imported from the scene automatically include references to their current materials. In addition, you can import scene materials into a graph in the same way as importing geometries.
• Material definitions are collections of properties such as color, transparency, and so on. These properties mirror the settings you might find on a typical shader. There are two nodes for creating material definitions: standard_surface_mat and constant_surface_mat.

Priority of materials

Materials are applied in order of priority.

• The default material of the host scene has the lowest priority. Although this material is automatically applied by default when you output a geometry, it does not get used unless there is no other material, such as a material reference on input geometry or a material explicitly assigned in the graph.
• Materials defined on Bifrost geometry have medium priority. This includes automatic material references on input geometry from the host scene, as well as materials assigned using assign_material.
• Materials (other than the default scene material) that are explicitly assigned in the host scene to the output of a graph have the highest priority. These materials override everything else.