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sn#095880 filedate 1974-04-05 generic text, type T, neo UTF8
~λ13;P17;JUFA
4.2 COPY, KILL AND DUAL.
4.2.1 "C" Copy.
This command copies the body or face from the top of stack in a reasonable
manner and pushs it down. The copy of a body includes all the parts of
that body. The copy of a face, creates a two-faced body lamina coincident
with the given face.
4.2.2 "K" Kill.
This command takes the top body, face, edge or vertex and
attempts to delete it in a reasonable manner. Kill of a body deletes
it and all its parts. Kill of a face removes the given face and all
its edges and vertices but one vertex, which is placed in the center
of the given face and is returned to the stack. Kill of an edge
removes the given edge and its negative face, NFACE(E). Kill of a
vertex removes the vertex and all its edges and faces but one face,
which is returned to the stack. The kill operation is not defined in
cases which would leave one-sided faces or dangling edges; however
the necessary trihedral restrictions are not imposed so that certain
illegal kills are possible and other illegal kills are fatal.
4.2.3 "αK" Edge-Vertex Kill.
The "αK" kill of an edge removes the edge and its negative
vertex, NVT(E); the positive vertex, PVT(E), is repositioned to be at the
center of the original edge. The PVT(E) vertex is returned to the stack.
4.2.4 "βD" Dual.
~W1,500;JUFA
The "βD" command makes the face/vertex dual of a body; that
is all the faces become vertices and all the vertices become faces.
This command will turn dodecahedrons into icosahedrons (or jacks
into horny octahedrons) as illustrated.
~W1,1260;
H2;X0.70;
L270,-400;
*FIG424.PLT;FA