int tessComputeInterior( TESStesselator *tess )
/*
* tessComputeInterior( tess ) computes the planar arrangement specified
* by the given contours, and further subdivides this arrangement
* into regions. Each region is marked "inside" if it belongs
* to the polygon, according to the rule given by tess->windingRule.
* Each interior region is guaranteed be monotone.
*/
{
TESSvertex *v, *vNext;
/* Each vertex defines an event for our sweep line. Start by inserting
* all the vertices in a priority queue. Events are processed in
* lexicographic order, ie.
*
* e1 < e2 iff e1.x < e2.x || (e1.x == e2.x && e1.y < e2.y)
*/
RemoveDegenerateEdges( tess );
if ( !InitPriorityQ( tess ) ) return 0; /* if error */
InitEdgeDict( tess );
while( (v = (TESSvertex *)pqExtractMin( tess->pq )) != NULL ) {
for( ;; ) {
vNext = (TESSvertex *)pqMinimum( tess->pq );
if( vNext == NULL || ! VertEq( vNext, v )) break;
/* Merge together all vertices at exactly the same location.
* This is more efficient than processing them one at a time,
* simplifies the code (see ConnectLeftDegenerate), and is also
* important for correct handling of certain degenerate cases.
* For example, suppose there are two identical edges A and B
* that belong to different contours (so without this code they would
* be processed by separate sweep events). Suppose another edge C
* crosses A and B from above. When A is processed, we split it
* at its intersection point with C. However this also splits C,
* so when we insert B we may compute a slightly different
* intersection point. This might leave two edges with a small
* gap between them. This kind of error is especially obvious
* when using boundary extraction (TESS_BOUNDARY_ONLY).
*/
vNext = (TESSvertex *)pqExtractMin( tess->pq );
SpliceMergeVertices( tess, v->anEdge, vNext->anEdge );
}
SweepEvent( tess, v );
}
/* Set tess->event for debugging purposes */
tess->event = ((ActiveRegion *) dictKey( dictMin( tess->dict )))->eUp->Org;
DebugEvent( tess );
DoneEdgeDict( tess );
DonePriorityQ( tess );
if ( !RemoveDegenerateFaces( tess, tess->mesh ) ) return 0;
tessMeshCheckMesh( tess->mesh );
return 1;
}
static void DoneEdgeDict( TESStesselator *tess )
{
ActiveRegion *reg;
while( (reg = (ActiveRegion *)dictKey( dictMin( tess->dict ))) != NULL ) {
/*
* At the end of all processing, the dictionary should contain
* only the two sentinel edges, plus at most one "fixable" edge
* created by ConnectRightVertex().
*/
if( ! reg->sentinel ) {
assert( reg->fixUpperEdge );
//assert( ++fixedEdges == 1 );
}
assert( reg->windingNumber == 0 );
DeleteRegion( tess, reg );
/* tessMeshDelete( reg->eUp );*/
}
dictDeleteDict( &tess->alloc, tess->dict );
}
static void DoneEdgeDict( GLUtesselator *tess )
{
ActiveRegion *reg;
int fixedEdges = 0;
/* __GL_DICTLISTKEY */ /* __GL_DICTLISTMIN */
while( (reg = (ActiveRegion *)dictKey( dictMin( tess->dict ))) != NULL ) {
/*
* At the end of all processing, the dictionary should contain
* only the two sentinel edges, plus at most one "fixable" edge
* created by ConnectRightVertex().
*/
if( ! reg->sentinel ) {
assert( reg->fixUpperEdge );
assert( ++fixedEdges == 1 );
}
assert( reg->windingNumber == 0 );
DeleteRegion( tess, reg );
/* __gl_meshDelete( reg->eUp );*/
}
dictDeleteDict( tess->dict ); /* __gl_dictListDeleteDict */
}
