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Peter Hachenberger 2008-06-15 21:32:49 +00:00
parent 24892799e2
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1 changed files with 7 additions and 8 deletions

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@ -26,13 +26,12 @@ decomposing both polyhedra into convex pieces, compute pair-wise
Minkowski sums of the convex pieces, and unite the pair-wise sums. Minkowski sums of the convex pieces, and unite the pair-wise sums.
While it is desirable to have a decomposition into a minimum number of While it is desirable to have a decomposition into a minimum number of
pieces, this problem is know to be NP-hard~\cite{cgal:c--}. Our pieces, this problem is know to be NP-hard. Our implementation
implementation decomposes a Nef polyhedron $N$ into $O(r^2)$ convex decomposes a Nef polyhedron $N$ into $O(r^2)$ convex pieces, where $r$
pieces, where $r$ is the number of edges, which have two adjacent is the number of edges, which have two adjacent facets that span an
facets that span an angle of more than 180 degrees with respect to the angle of more than 180 degrees with respect to the interior of the
interior of the polyhedron. Those edges are also called reflex edges. polyhedron. Those edges are also called reflex edges. The bound of
The bound of $O(r^2)$ convex pieces is worst-case $O(r^2)$ convex pieces is worst-case optimal.
optimal~\cite{cgal:c--}.
At the moment our implementation is restricted to the decomposition of At the moment our implementation is restricted to the decomposition of
finite point sets. If the input polyhedron is infinite, i.e., the finite point sets. If the input polyhedron is infinite, i.e., the
@ -52,4 +51,4 @@ subdivided into convex pieces. The convex pieces can then be used by
traversing $N$, or by converting them into separate Nef polyhedra, as traversing $N$, or by converting them into separate Nef polyhedra, as
shown in the example code. shown in the example code.
\ccIncludeExampleCode{Convex_decomposition_3/.cpp} \ccIncludeExampleCode{Convex_decomposition_3/list_of_convex_parts.cpp}