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A method has also been added to return a subgraph that is a shortest path between two vertices in the same component of a graph. The shortest path from
A to G in Figure 5-18 is the path (A, B, H, F, G).
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For cycle vertices, a method has been added to return a subgraph that is a shortest cycle that contains the vertex. The shortest cycle of the graph in Figure 5-18 that contains
C is the cycle (C, B, H, D, C).
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Figure 5-18. The Connectivity Graph
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Figure 5-19 shows a blank body consisting of a block with two slots cut out of it and a tool body consisting of a cylinder that penetrates the block three times.
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Figure 5-19. The Blank and Tool Bodies
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The first stage of the selective Booleans creates a non-regular unite of the two bodies and attaches cellular topology to the result (Figure 5-20). In addition, the connectivity graph (Figure 5-18) of the resulting cells is returned and the vertices, or cells, of the graph are marked in a way that lets one know which body or bodies they came from.
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Figure 5-20. The Blank Body After the First Stage of Selective Booleans
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Graphs may be copied by calling the
copy method or created for an
ENTITY_LIST of
CELLs by calling
api_create_graph_from_cells. Figure 5-18 is the graph that is created if the eight cells in Figure 5-20 are sent to
api_create_graph_from_cells.
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The
gvertex and
gedge classes also have pointers for holding true or false information as to what
kind of vertex or edge they are. The meaning of
kind is left to the user. A vertex or edge may (or may not) be any number of
kinds.
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For example, the cells of the body in Figure 5-20 may be marked as
kind 0 (meaning being from the tool body) or
kind 1 (meaning being from the blank body). Some cells may be of both
kind 0 and
kind 1.
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The
kind method of the class
generic_graph returns a subgraph of all edges and vertices of, or not of, a given
kind. The graph in Figure 5-18 is returned by the first stage of the selective Boolean on the bodies in Figure 5-19. The linear subgraph formed by the vertices (A, B, C, D, E, F, G) are from the tool body and marked as
kind 0. The subgraph formed by the vertices (B, H, D, G) are from the blank body and are marked as
kind 1.
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The second stage of the selective Boolean engine takes the non-regular united body and a list or graph of cells. It returns a regularized body that is made up of the given cells or vertices of the graph (Figure 5-21).
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Figure 5-21. The Result of Picking C, G, and H to Keep
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