Constructive Solid Geometry (CSG) are ordered binary trees. CSG schemes are unambiguous but non-unique. The domain of a CSG scheme depends on the half-spaces which underlie its set of primitive solids and on available motional and combinational operators.
CSG trees with uninstantiated parameters can be used to represent
generic objects (also
called procedure-,macro-, or parametric objects or object schemata).The
validity of such generic object representations
also may be ensured easily.
CSG object is built from the standard primitives ,using regularised Boolean operations and rigid motions.The basic primitives for 2D operations may be any type of quadrilaterals and ofcourse any type of curvely bounded planes also provided the boundary should be well defined.
The basic primitives for
3D operations may be parallelopipped
(block) ,triangular prism,sphere,cylinder,cone,torus.They
are generic in the sense that they represent
shapes that must be instantiated by
the user to chosen dimensions.
After instantiation primitive objects
can be combined using regularised Boolean
operations.The operations are regularised Union
denoted here by RUNION , regularised intersection
denoted by RINT, regularised negation denoted by
RNEG.They differ from the corresponding
set-theoretic operations in that the
result is the closure of operation
on the interior of two polygons or
solids ,and they are used to eliminate
"dangling" lower dimensional structures.
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