Kstars

sweep.h
1 /*
2 ** Author: Eric Veach, July 1994.
3 **
4 */
5 
6 #ifndef __sweep_h_
7 #define __sweep_h_
8 
9 #include "mesh.h"
10 
11 /* __gl_computeInterior( tess ) computes the planar arrangement specified
12  * by the given contours, and further subdivides this arrangement
13  * into regions. Each region is marked "inside" if it belongs
14  * to the polygon, according to the rule given by tess->windingRule.
15  * Each interior region is guaranteed be monotone.
16  */
17 int __gl_computeInterior(GLUtesselator *tess);
18 
19 /* The following is here *only* for access by debugging routines */
20 
21 #include "dict.h"
22 
23 /* For each pair of adjacent edges crossing the sweep line, there is
24  * an ActiveRegion to represent the region between them. The active
25  * regions are kept in sorted order in a dynamic dictionary. As the
26  * sweep line crosses each vertex, we update the affected regions.
27  */
28 
29 struct ActiveRegion
30 {
31  GLUhalfEdge *eUp; /* upper edge, directed right to left */
32  DictNode *nodeUp; /* dictionary node corresponding to eUp */
33  int windingNumber; /* used to determine which regions are
34  * inside the polygon */
35  GLboolean inside; /* is this region inside the polygon? */
36  GLboolean sentinel; /* marks fake edges at t = +/-infinity */
37  GLboolean dirty; /* marks regions where the upper or lower
38  * edge has changed, but we haven't checked
39  * whether they intersect yet */
40  GLboolean fixUpperEdge; /* marks temporary edges introduced when
41  * we process a "right vertex" (one without
42  * any edges leaving to the right) */
43 };
44 
45 #define RegionBelow(r) ((ActiveRegion *)dictKey(dictPred((r)->nodeUp)))
46 #define RegionAbove(r) ((ActiveRegion *)dictKey(dictSucc((r)->nodeUp)))
47 
48 #endif
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