
228 CHAPTER 7. PLANAR ORTHOGONAL AND POLYLINE DRAWINGS
(a) (b)
(c) (d)
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v
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v
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v
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v
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v
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v
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Figure 7.2 An illustration showing the creation of the canonical ordering in reverse order.
(a) The first vertex v
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is about to be removed with the exter n al cycle highlighted. (b)
Removal of the next vertex, v
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. (c) Removal of vertex v
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. (d) The final canonical ordering
of the vertices.
(a) (b)
w
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w
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v
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v
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Figure 7.3 Inserting a vertex using the canonical order i ng. This example does not follow
the vertex placement techniques employed by the standard algorithms used to produce
good area drawings. (a) The graph G
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, with its e xt er ...