Shading

A material is a collection of shaders. Each shader has various parameters which control its behavior during the rendering process. A material is a collection of one or more SHOPs. For example, a material can contain a surface shader and a displacement shader.

Materials may be assigned at the object level (using the shop_materialpath parameter). Materials may also be assigned at the SOP level using a material SOP. The material SOP allows a material to be applied to a group of primitives. Materials may also be applied as a point attribute. This is used to assign a material to each instance when performing point instancing.

Materials may exist inside other materials. For example, to create a bumpy glass material, you can create a material which has a Glass material (defining the surface shader) and a Bump material (defining the bump) and wire the appropriate outputs from the sub-materials into the outputs of the new material.

There are several different types of SHOPs that are used in different areas of Houdini.