CSG stands for Constructive Solid Geometry. POV-Ray allows us to construct complex solids by
combining primitive shapes in four different ways. In the
statement, two or more shapes are added together. With the
statement, two or more shapes are combined to make a new shape that consists of the area common to both shapes. The
statement, an initial shape has all subsequent shapes subtracted from it.
And last but not least
merge, which is like a union where
the surfaces inside the union are removed (useful in transparent CSG objects). We will deal with each of these in
detail in the next few sections.
CSG objects can be extremely complex. They can be deeply nested. In other words there can be unions of differences
or intersections of merges or differences of intersections or even unions of intersections of differences of merges...
ad infinitum. CSG objects are (almost always) finite objects and thus respond to auto-bounding and can be transformed
like any other POV primitive shape.