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;
}
int tessTesselate( TESStesselator *tess, int windingRule, int elementType,
int polySize, int vertexSize, const TESSreal* normal )
{
TESSmesh *mesh;
int rc = 1;
if (tess->vertices != NULL) {
tess->alloc.memfree( tess->alloc.userData, tess->vertices );
tess->vertices = 0;
}
if (tess->elements != NULL) {
tess->alloc.memfree( tess->alloc.userData, tess->elements );
tess->elements = 0;
}
if (tess->vertexIndices != NULL) {
tess->alloc.memfree( tess->alloc.userData, tess->vertexIndices );
tess->vertexIndices = 0;
}
tess->vertexIndexCounter = 0;
if (normal)
{
tess->normal[0] = normal[0];
tess->normal[1] = normal[1];
tess->normal[2] = normal[2];
}
tess->windingRule = windingRule;
if (vertexSize < 2)
vertexSize = 2;
if (vertexSize > 3)
vertexSize = 3;
if (setjmp(tess->env) != 0) {
/* come back here if out of memory */
return 0;
}
if (!tess->mesh)
{
return 0;
}
/* Determine the polygon normal and project vertices onto the plane
* of the polygon.
*/
tessProjectPolygon( 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.
*/
if ( !tessComputeInterior( tess ) ) {
longjmp(tess->env,1); /* could've used a label */
}
mesh = tess->mesh;
/* If the user wants only the boundary contours, we throw away all edges
* except those which separate the interior from the exterior.
* Otherwise we tessellate all the regions marked "inside".
*/
if (elementType == TESS_BOUNDARY_CONTOURS) {
rc = tessMeshSetWindingNumber( mesh, 1, TRUE );
} else {
rc = tessMeshTessellateInterior( mesh );
}
if (rc == 0) longjmp(tess->env,1); /* could've used a label */
tessMeshCheckMesh( mesh );
if (elementType == TESS_BOUNDARY_CONTOURS) {
OutputContours( tess, mesh, vertexSize ); /* output contours */
}
else
{
OutputPolymesh( tess, mesh, elementType, polySize, vertexSize ); /* output polygons */
}
tessMeshDeleteMesh( &tess->alloc, mesh );
tess->mesh = NULL;
if (tess->outOfMemory)
return 0;
return 1;
}