Reference:Clipped By Object Modifier

The clipped_by statement is technically an object modifier but it provides a type of CSG similar to CSG intersection. The syntax is:

CLIPPED_BY:
  clipped_by { UNTEXTURED_SOLID_OBJECT... } |
  clipped_by { bounded_by }

Where UNTEXTURED_SOLID_OBJECT is one or more solid objects which have had no texture applied. For example:

object {
  My_Thing
  clipped_by{plane{y,0}}
  }

Every part of the object My_Thing that is inside the plane is retained while the remaining part is clipped off and discarded. In an intersection object the hole is closed off. With clipped_by it leaves an opening. For example the following figure shows object A being clipped by object B.

An object clipped by another object.

You may use clipped_by to slice off portions of any shape. In many cases it will also result in faster rendering times than other methods of altering a shape. Occasionally you will want to use the clipped_by and bounded_by options with the same object. The following shortcut saves typing and uses less memory.

object {
  My_Thing
  bounded_by { box { <0,0,0>, <1,1,1> } }
  clipped_by { bounded_by }
  }

This tells POV-Ray to use the same box as a clip that was used as a bound.