Editing Blender (software) (section)

=====Materials=====
Materials define the look of [[polygon mesh|meshes]], [[Non-uniform rational B-spline|NURBS curves]], and other geometric objects. They consist of three [[shader]]s to define the mesh's surface appearance, volume inside, and surface displacement.<ref name="manual-cycles-intro" />

The ''surface shader'' defines the light interaction at the surface of the mesh. One or more bidirectional scattering distribution functions, or [[Bidirectional scattering distribution function|BSDFs]], can specify if incoming light is reflected, refracted into the mesh, or absorbed.<ref name="manual-cycles-intro" /> The [[Alpha compositing|alpha value]] is one measure of translucency.

When the surface shader does not reflect or absorb light, it enters the volume (light transmission). If no volume shader is specified, it will pass straight through (or be refracted, see [[Refractive index|refractive index or IOR]]) to another side of the mesh.

If one is defined, a ''volume shader'' describes the light interaction as it passes through the volume of the mesh. Light may be scattered, absorbed, or even emitted{{Clarify|reason=|date=December 2019}} at any point in the volume.<ref name="manual-cycles-intro" />

The shape of the surface may be altered by ''displacement shaders''. In this way, textures can be used to make the mesh surface more detailed.

Depending on the settings, the displacement may be virtual-only modifying the [[surface normals]] to give the impression of displacement (also known as [[bump mapping]]) – real, or a combination of real displacement with bump mapping.<ref name="manual-cycles-intro" />