Stellarium  0.90.0
sweep.h
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30 /*
31 ** Author: Eric Veach, July 1994.
32 **
33 */
34 
35 #ifndef __sweep_h_
36 #define __sweep_h_
37 
38 #include "mesh.h"
39 
40 /* __gl_computeInterior( tess ) computes the planar arrangement specified
41  * by the given contours, and further subdivides this arrangement
42  * into regions. Each region is marked "inside" if it belongs
43  * to the polygon, according to the rule given by tess->windingRule.
44  * Each interior region is guaranteed be monotone.
45  */
46 int __gl_computeInterior(GLUEStesselator* tess);
47 
48 /* The following is here *only* for access by debugging routines */
49 
50 #include "dict.h"
51 
52 /* For each pair of adjacent edges crossing the sweep line, there is
53  * an ActiveRegion to represent the region between them. The active
54  * regions are kept in sorted order in a dynamic dictionary. As the
55  * sweep line crosses each vertex, we update the affected regions.
56  */
57 
59 {
60  GLUEShalfEdge* eUp; /* upper edge, directed right to left */
61  DictNode* nodeUp; /* dictionary node corresponding to eUp */
62  int windingNumber; /* used to determine which regions are
63  * inside the polygon */
64  GLboolean inside; /* is this region inside the polygon? */
65  GLboolean sentinel; /* marks fake edges at t = +/-infinity */
66  GLboolean dirty; /* marks regions where the upper or lower
67  * edge has changed, but we haven't checked
68  * whether they intersect yet */
69  GLboolean fixUpperEdge; /* marks temporary edges introduced when
70  * we process a "right vertex" (one without
71  * any edges leaving to the right) */
72 };
73 
74 #define RegionBelow(r) ((ActiveRegion*)dictKey(dictPred((r)->nodeUp)))
75 #define RegionAbove(r) ((ActiveRegion*)dictKey(dictSucc((r)->nodeUp)))
76 
77 #endif /* __sweep_h_ */