static void AddSentinel( TESStesselator *tess, TESSreal smin, TESSreal smax, TESSreal t )
/*
* We add two sentinel edges above and below all other edges,
* to avoid special cases at the top and bottom.
*/
{
TESShalfEdge *e;
ActiveRegion *reg = (ActiveRegion *)bucketAlloc( tess->regionPool );
if (reg == NULL) longjmp(tess->env,1);
e = tessMeshMakeEdge( tess->mesh );
if (e == NULL) longjmp(tess->env,1);
e->Org->s = smax;
e->Org->t = t;
e->Dst->s = smin;
e->Dst->t = t;
tess->event = e->Dst; /* initialize it */
reg->eUp = e;
reg->windingNumber = 0;
reg->inside = FALSE;
reg->fixUpperEdge = FALSE;
reg->sentinel = TRUE;
reg->dirty = FALSE;
reg->nodeUp = dictInsert( tess->dict, reg );
if (reg->nodeUp == NULL) longjmp(tess->env,1);
}
void tessAddContour( TESStesselator *tess, int size, const void* vertices,
int stride, int numVertices )
{
const unsigned char *src = (const unsigned char*)vertices;
TESShalfEdge *e;
int i;
if ( tess->mesh == NULL )
tess->mesh = tessMeshNewMesh( &tess->alloc );
if ( tess->mesh == NULL ) {
tess->outOfMemory = 1;
return;
}
if ( size < 2 )
size = 2;
if ( size > 3 )
size = 3;
e = NULL;
for( i = 0; i < numVertices; ++i )
{
const TESSreal* coords = (const TESSreal*)src;
src += stride;
if( e == NULL ) {
/* Make a self-loop (one vertex, one edge). */
e = tessMeshMakeEdge( tess->mesh );
if ( e == NULL ) {
tess->outOfMemory = 1;
return;
}
if ( !tessMeshSplice( tess->mesh, e, e->Sym ) ) {
tess->outOfMemory = 1;
return;
}
} else {
/* Create a new vertex and edge which immediately follow e
* in the ordering around the left face.
*/
if ( tessMeshSplitEdge( tess->mesh, e ) == NULL ) {
tess->outOfMemory = 1;
return;
}
e = e->Lnext;
}
/* The new vertex is now e->Org. */
e->Org->coords[0] = coords[0];
e->Org->coords[1] = coords[1];
if ( size > 2 )
e->Org->coords[2] = coords[2];
else
e->Org->coords[2] = 0;
/* Store the insertion number so that the vertex can be later recognized. */
e->Org->idx = tess->vertexIndexCounter++;
/* The winding of an edge says how the winding number changes as we
* cross from the edge''s right face to its left face. We add the
* vertices in such an order that a CCW contour will add +1 to
* the winding number of the region inside the contour.
*/
e->winding = 1;
e->Sym->winding = -1;
}
}
