Reference:Material

One of the changes in POV-Ray v3.1 was the removal of several items from texture { finish{...} } and to move them to the new interior statement. The halo statement, formerly part of texture, is now renamed media and made a part of the interior.

This split was deliberate and purposeful (see Why are Interior and Media Necessary?) however beta testers pointed out that it made it difficult to entirely describe the surface properties and interior of an object in one statement that can be referenced by a single identifier in a texture library.

The result is that we created a wrapper around texture and interior which we call material.

The syntax is:

MATERIAL:
  material { [MATERIAL_IDENTIFIER][MATERIAL_ITEMS...] }
MATERIAL_ITEMS:
  TEXTURE | INTERIOR_TEXTURE | INTERIOR | TRANSFORMATIONS

For example:

#declare MyGlass=material{ texture{ Glass_T } interior{ Glass_I }}
object { MyObject material{ MyGlass}}

Internally, the material is not attached to the object. The material is just a container that brings the texture and interior to the object. It is the texture and interior itself that is attached to the object. Users should still consider texture and interior as separate items attached to the object.

The material is just a bucket to carry them. If the object already has a texture, then the material texture is layered over it. If the object already has an interior, the material interior fully replaces it and the old interior is destroyed. Transformations inside the material affect only the textures and interiors which are inside the material{} wrapper and only those textures or interiors specified are affected. For example:

object {
  MyObject
    material {
      texture { MyTexture }
      scale 4         //affects texture but not object or interior
      interior { MyInterior }
      translate 5*x   //affects texture and interior, not object
      }
  }

Note: The material statement has nothing to do with the material_map statement. A material_map is not a way to create patterned material. See Material Maps for explanation of this unrelated, yet similarly named, older feature.