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 stackPush( EdgeStack *stack, TESShalfEdge *e )
{
EdgeStackNode *node = (EdgeStackNode *)bucketAlloc( stack->nodeBucket );
if ( ! node ) return;
node->edge = e;
node->next = stack->top;
stack->top = node;
}
/* tessMeshSplice( eOrg, eDst ) is the basic operation for changing the
* mesh connectivity and topology. It changes the mesh so that
* eOrg->Onext <- OLD( eDst->Onext )
* eDst->Onext <- OLD( eOrg->Onext )
* where OLD(...) means the value before the meshSplice operation.
*
* This can have two effects on the vertex structure:
* - if eOrg->Org != eDst->Org, the two vertices are merged together
* - if eOrg->Org == eDst->Org, the origin is split into two vertices
* In both cases, eDst->Org is changed and eOrg->Org is untouched.
*
* Similarly (and independently) for the face structure,
* - if eOrg->Lface == eDst->Lface, one loop is split into two
* - if eOrg->Lface != eDst->Lface, two distinct loops are joined into one
* In both cases, eDst->Lface is changed and eOrg->Lface is unaffected.
*
* Some special cases:
* If eDst == eOrg, the operation has no effect.
* If eDst == eOrg->Lnext, the new face will have a single edge.
* If eDst == eOrg->Lprev, the old face will have a single edge.
* If eDst == eOrg->Onext, the new vertex will have a single edge.
* If eDst == eOrg->Oprev, the old vertex will have a single edge.
*/
int tessMeshSplice( TESSmesh* mesh, TESShalfEdge *eOrg, TESShalfEdge *eDst )
{
int joiningLoops = FALSE;
int joiningVertices = FALSE;
if( eOrg == eDst ) return 1;
if( eDst->Org != eOrg->Org ) {
/* We are merging two disjoint vertices -- destroy eDst->Org */
joiningVertices = TRUE;
KillVertex( mesh, eDst->Org, eOrg->Org );
}
if( eDst->Lface != eOrg->Lface ) {
/* We are connecting two disjoint loops -- destroy eDst->Lface */
joiningLoops = TRUE;
KillFace( mesh, eDst->Lface, eOrg->Lface );
}
/* Change the edge structure */
Splice( eDst, eOrg );
if( ! joiningVertices ) {
TESSvertex *newVertex = (TESSvertex*)bucketAlloc( mesh->vertexBucket );
if (newVertex == NULL) return 0;
/* We split one vertex into two -- the new vertex is eDst->Org.
* Make sure the old vertex points to a valid half-edge.
*/
MakeVertex( newVertex, eDst, eOrg->Org );
eOrg->Org->anEdge = eOrg;
}
if( ! joiningLoops ) {
TESSface *newFace = (TESSface*)bucketAlloc( mesh->faceBucket );
if (newFace == NULL) return 0;
/* We split one loop into two -- the new loop is eDst->Lface.
* Make sure the old face points to a valid half-edge.
*/
MakeFace( newFace, eDst, eOrg->Lface );
eOrg->Lface->anEdge = eOrg;
}
return 1;
}
/* tessMeshMakeEdge creates one edge, two vertices, and a loop (face).
* The loop consists of the two new half-edges.
*/
TESShalfEdge *tessMeshMakeEdge( TESSmesh *mesh )
{
TESSvertex *newVertex1 = (TESSvertex*)bucketAlloc(mesh->vertexBucket);
TESSvertex *newVertex2 = (TESSvertex*)bucketAlloc(mesh->vertexBucket);
TESSface *newFace = (TESSface*)bucketAlloc(mesh->faceBucket);
TESShalfEdge *e;
/* if any one is null then all get freed */
if (newVertex1 == NULL || newVertex2 == NULL || newFace == NULL) {
if (newVertex1 != NULL) bucketFree( mesh->vertexBucket, newVertex1 );
if (newVertex2 != NULL) bucketFree( mesh->vertexBucket, newVertex2 );
if (newFace != NULL) bucketFree( mesh->faceBucket, newFace );
return NULL;
}
e = MakeEdge( mesh, &mesh->eHead );
if (e == NULL) return NULL;
MakeVertex( newVertex1, e, &mesh->vHead );
MakeVertex( newVertex2, e->Sym, &mesh->vHead );
MakeFace( newFace, e, &mesh->fHead );
return e;
}
/* tessMeshDelete( eDel ) removes the edge eDel. There are several cases:
* if (eDel->Lface != eDel->Rface), we join two loops into one; the loop
* eDel->Lface is deleted. Otherwise, we are splitting one loop into two;
* the newly created loop will contain eDel->Dst. If the deletion of eDel
* would create isolated vertices, those are deleted as well.
*
* This function could be implemented as two calls to tessMeshSplice
* plus a few calls to memFree, but this would allocate and delete
* unnecessary vertices and faces.
*/
int tessMeshDelete( TESSmesh *mesh, TESShalfEdge *eDel )
{
TESShalfEdge *eDelSym = eDel->Sym;
int joiningLoops = FALSE;
/* First step: disconnect the origin vertex eDel->Org. We make all
* changes to get a consistent mesh in this "intermediate" state.
*/
if( eDel->Lface != eDel->Rface ) {
/* We are joining two loops into one -- remove the left face */
joiningLoops = TRUE;
KillFace( mesh, eDel->Lface, eDel->Rface );
}
if( eDel->Onext == eDel ) {
KillVertex( mesh, eDel->Org, NULL );
} else {
/* Make sure that eDel->Org and eDel->Rface point to valid half-edges */
eDel->Rface->anEdge = eDel->Oprev;
eDel->Org->anEdge = eDel->Onext;
Splice( eDel, eDel->Oprev );
if( ! joiningLoops ) {
TESSface *newFace= (TESSface*)bucketAlloc( mesh->faceBucket );
if (newFace == NULL) return 0;
/* We are splitting one loop into two -- create a new loop for eDel. */
MakeFace( newFace, eDel, eDel->Lface );
}
}
/* Claim: the mesh is now in a consistent state, except that eDel->Org
* may have been deleted. Now we disconnect eDel->Dst.
*/
if( eDelSym->Onext == eDelSym ) {
KillVertex( mesh, eDelSym->Org, NULL );
KillFace( mesh, eDelSym->Lface, NULL );
} else {
/* Make sure that eDel->Dst and eDel->Lface point to valid half-edges */
eDel->Lface->anEdge = eDelSym->Oprev;
eDelSym->Org->anEdge = eDelSym->Onext;
Splice( eDelSym, eDelSym->Oprev );
}
/* Any isolated vertices or faces have already been freed. */
KillEdge( mesh, eDel );
return 1;
}
/* really tessDictListInsertBefore */
DictNode *dictInsertBefore( Dict *dict, DictNode *node, DictKey key )
{
DictNode *newNode;
do {
node = node->prev;
} while( node->key != NULL && ! (*dict->leq)(dict->frame, node->key, key));
newNode = (DictNode *)bucketAlloc( dict->nodePool );
if (newNode == NULL) return NULL;
newNode->key = key;
newNode->next = node->next;
node->next->prev = newNode;
newNode->prev = node;
node->next = newNode;
return newNode;
}
/* MakeEdge creates a new pair of half-edges which form their own loop.
* No vertex or face structures are allocated, but these must be assigned
* before the current edge operation is completed.
*/
static TESShalfEdge *MakeEdge( TESSmesh* mesh, TESShalfEdge *eNext )
{
TESShalfEdge *e;
TESShalfEdge *eSym;
TESShalfEdge *ePrev;
EdgePair *pair = (EdgePair *)bucketAlloc( mesh->edgeBucket );
if (pair == NULL) return NULL;
e = &pair->e;
eSym = &pair->eSym;
/* Make sure eNext points to the first edge of the edge pair */
if( eNext->Sym < eNext ) { eNext = eNext->Sym; }
/* Insert in circular doubly-linked list before eNext.
* Note that the prev pointer is stored in Sym->next.
*/
ePrev = eNext->Sym->next;
eSym->next = ePrev;
ePrev->Sym->next = e;
e->next = eNext;
eNext->Sym->next = eSym;
e->Sym = eSym;
e->Onext = e;
e->Lnext = eSym;
e->Org = NULL;
e->Lface = NULL;
e->winding = 0;
e->activeRegion = NULL;
e->mark = 0;
eSym->Sym = e;
eSym->Onext = eSym;
eSym->Lnext = e;
eSym->Org = NULL;
eSym->Lface = NULL;
eSym->winding = 0;
eSym->activeRegion = NULL;
eSym->mark = 0;
return e;
}
/* tessMeshAddEdgeVertex( eOrg ) creates a new edge eNew such that
* eNew == eOrg->Lnext, and eNew->Dst is a newly created vertex.
* eOrg and eNew will have the same left face.
*/
TESShalfEdge *tessMeshAddEdgeVertex( TESSmesh *mesh, TESShalfEdge *eOrg )
{
TESShalfEdge *eNewSym;
TESShalfEdge *eNew = MakeEdge( mesh, eOrg );
if (eNew == NULL) return NULL;
eNewSym = eNew->Sym;
/* Connect the new edge appropriately */
Splice( eNew, eOrg->Lnext );
/* Set the vertex and face information */
eNew->Org = eOrg->Dst;
{
TESSvertex *newVertex= (TESSvertex*)bucketAlloc( mesh->vertexBucket );
if (newVertex == NULL) return NULL;
MakeVertex( newVertex, eNewSym, eNew->Org );
}
eNew->Lface = eNewSym->Lface = eOrg->Lface;
return eNew;
}
static ActiveRegion *AddRegionBelow( TESStesselator *tess,
ActiveRegion *regAbove,
TESShalfEdge *eNewUp )
/*
* Add a new active region to the sweep line, *somewhere* below "regAbove"
* (according to where the new edge belongs in the sweep-line dictionary).
* The upper edge of the new region will be "eNewUp".
* Winding number and "inside" flag are not updated.
*/
{
ActiveRegion *regNew = (ActiveRegion *)bucketAlloc( tess->regionPool );
if (regNew == NULL) longjmp(tess->env,1);
regNew->eUp = eNewUp;
regNew->nodeUp = dictInsertBefore( tess->dict, regAbove->nodeUp, regNew );
if (regNew->nodeUp == NULL) longjmp(tess->env,1);
regNew->fixUpperEdge = FALSE;
regNew->sentinel = FALSE;
regNew->dirty = FALSE;
eNewUp->activeRegion = regNew;
return regNew;
}
/* tessMeshConnect( eOrg, eDst ) creates a new edge from eOrg->Dst
* to eDst->Org, and returns the corresponding half-edge eNew.
* If eOrg->Lface == eDst->Lface, this splits one loop into two,
* and the newly created loop is eNew->Lface. Otherwise, two disjoint
* loops are merged into one, and the loop eDst->Lface is destroyed.
*
* If (eOrg == eDst), the new face will have only two edges.
* If (eOrg->Lnext == eDst), the old face is reduced to a single edge.
* If (eOrg->Lnext->Lnext == eDst), the old face is reduced to two edges.
*/
TESShalfEdge *tessMeshConnect( TESSmesh *mesh, TESShalfEdge *eOrg, TESShalfEdge *eDst )
{
TESShalfEdge *eNewSym;
int joiningLoops = FALSE;
TESShalfEdge *eNew = MakeEdge( mesh, eOrg );
if (eNew == NULL) return NULL;
eNewSym = eNew->Sym;
if( eDst->Lface != eOrg->Lface ) {
/* We are connecting two disjoint loops -- destroy eDst->Lface */
joiningLoops = TRUE;
KillFace( mesh, eDst->Lface, eOrg->Lface );
}
/* Connect the new edge appropriately */
Splice( eNew, eOrg->Lnext );
Splice( eNewSym, eDst );
/* Set the vertex and face information */
eNew->Org = eOrg->Dst;
eNewSym->Org = eDst->Org;
eNew->Lface = eNewSym->Lface = eOrg->Lface;
/* Make sure the old face points to a valid half-edge */
eOrg->Lface->anEdge = eNewSym;
if( ! joiningLoops ) {
TESSface *newFace= (TESSface*)bucketAlloc( mesh->faceBucket );
if (newFace == NULL) return NULL;
/* We split one loop into two -- the new loop is eNew->Lface */
MakeFace( newFace, eNew, eOrg->Lface );
}
return eNew;
}