//
// s is a spoke pointing OUT from x
//
void Subdivision::optimize(Vec2& x, Edge *s)
{
Edge *start_spoke = s;
Edge *spoke = s;
do {
Edge *e = spoke->Lnext();
Edge *t = e->Oprev();
if( isInterior(e) && shouldSwap(x, e) )
swap(e);
else
{
spoke = spoke->Onext();
if( spoke == start_spoke )
break;
}
} while( true );
//
// Now, update all the triangles
spoke = start_spoke;
do {
Edge *e = spoke->Lnext();
Triangle *t = e->Lface();
if( t ) t->update(*this);
spoke = spoke->Onext();
} while( spoke != start_spoke );
}
void Subdivision::InsertSite(const Point2d& x)
// Inserts a new point into a subdivision representing a Delaunay
// triangulation, and fixes the affected edges so that the result
// is still a Delaunay triangulation. This is based on the
// pseudocode from Guibas and Stolfi (1985) p.120, with slight
// modifications and a bug fix.
{
Edge* e = Locate(x);
if ((x == e->Org2d()) || (x == e->Dest2d())) // point is already in
return;
else if (OnEdge(x, e)) {
e = e->Oprev();
DeleteEdge(e->Onext());
}
// Connect the new point to the vertices of the containing
// triangle (or quadrilateral, if the new point fell on an
// existing edge.)
Edge* base = MakeEdge();
base->EndPoints(e->Org(), new Point2d(x));
Splice(base, e);
startingEdge = base;
do {
base = Connect(e, base->Sym());
e = base->Oprev();
} while (e->Lnext() != startingEdge);
// Examine suspect edges to ensure that the Delaunay condition
// is satisfied.
do {
Edge* t = e->Oprev();
if (RightOf(t->Dest2d(), e) &&
InCircle(e->Org2d(), t->Dest2d(), e->Dest2d(), x)) {
Swap(e);
e = e->Oprev();
}
else if (e->Onext() == startingEdge) // no more suspect edges
return;
else // pop a suspect edge
e = e->Onext()->Lprev();
} while (TRUE);
}
int main() {
using cgl::Point2d;
using cgl::Edge;
using cgl::make_edge;
// Point2d *a = new Point2d(0.0, 0.0); // 0
// Point2d *b = new Point2d(1.0, 0.0); // 1
// Point2d *c = new Point2d(1.0, 1.0); // 2
// Point2d *d = new Point2d(0.0, 1.0); // 3
Edge *ea = make_edge(0, 1);
Edge *eb = make_edge(ea->Dest(), 2);
Edge *ec = make_edge(eb->Dest(), 3);
Edge *ed = make_edge(ec->Dest(), 0);
Edge *ee = make_edge(eb->Dest(), ea->Org());
// Connect eb to ea->Dest()
splice(ea->Sym(), eb);
// Connect ec to eb->Dest()
splice(eb->Sym(), ec);
// Connect ed to ec->Sym() and ea
splice(ec->Sym(), ed);
splice(ed->Sym(), ea);
// Connect ee to ec and ea -- this is equivalent to Delaunay::connect
splice(ee, eb->Lnext());
splice(ee->Sym(), ea);
// Traverse the convex hull
if (ea->Dnext() != eb->Sym()) {
std::cerr << "Error: ea->Dnext() != eb->Sym()" << std::endl;
return 1;
}
if (eb->Dnext() != ec->Sym()) {
std::cerr << "Error: eb->Dnext() != ec->Sym()" << std::endl;
return 1;
}
if (ec->Dnext() != ed->Sym()) {
std::cerr << "Error: ec->Dnext() != ed->Sym()" << std::endl;
return 1;
}
if (ed->Dprev() != ee) {
std::cerr << "Error: ed->Dprev() != ee" << std::endl;
return 1;
}
// Cross linkage -- test algebra
// Rot / invRot
if (ee->Rot()->Org() != ed->invRot()->Org()) {
std::cerr << "Error: ee->Rot()->Org() != ed->invRot()->Org()" <<
std::endl;
return 1;
}
// Sym
if (ee->Sym()->Org() != 0) {
std::cerr << "Error: ee->Sym()->Org() != a" << std::endl;
return 1;
}
// Onext
if (ee->Onext() != eb->Sym()) {
std::cerr << "Error: ee->Onext() != eb->Sym()" << std::endl;
return 1;
}
// Oprev
if (ee->Oprev() != ec) {
std::cerr << "Error: ee->Oprev() != ec" << std::endl;
return 1;
}
// Dnext
if (ee->Dnext() != ed) {
std::cerr << "Error: ee->Dnext() != ed" << std::endl;
return 1;
}
// Dprev
if (ee->Dprev() != ea->Sym()) {
std::cerr << "Error: ee->Dprev() != ea->Sym()" << std::endl;
return 1;
}
// Lnext
if (ee->Lnext() != ea) {
std::cerr << "Error: ee->Lnext() != ea" << std::endl;
return 1;
}
// Lprev
if (ee->Lprev() != eb) {
std::cerr << "Error: ee->Lprev() != eb" << std::endl;
return 1;
}
// Rnext
if (ee->Rnext() != ec->Sym()) {
std::cerr << "Error: ee->Rnext() != ec->Sym()" << std::endl;
return 1;
}
// Rprev
if (ee->Rprev() != ed->Sym()) {
std::cerr << "Error: ee->Rprev() != ed->Sym()" << std::endl;
return 1;
}
// Org / Dest
if (ed->Org() != 3) {
std::cerr << "Error: ed->Org() != d" << std::endl;
return 1;
}
if (ed->Dest() != 0) {
std::cerr << "Error: ed->Dest() != a" << std::endl;
return 1;
}
if (ee->Org() != 2) {
std::cerr << "Error: ee->Org() != c" << std::endl;
return 1;
}
if (ee->Dest() != 0) {
std::cerr << "Error: ee->Dest() != a" << std::endl;
return 1;
}
// Let the system clean up the memory
return 0;
}
void Edge::killEdge(Edge *e) {
Edge *f = e->Sym();
if (e->Onext() != e) splice(e, e->Oprev());
if (f->Onext() != f) splice(f, f->Oprev());
delete (QuadEdge *)(e - e->r);
}
/*Type of Cut Strategy is defined as:
* (useAltCut, useVertical) = (true, true) => Alternating Cuts
* (useAltCut, useVertical) = (true, false) => Horizontal Cuts*
* (useAltCut, useVertical) = (false, true) => Vertical Cuts
* */
void delaunay(Vertex **ppVertices, long numVertices, Edge **ppLe, Edge **ppRe,
bool useAltCuts, bool useVertical) {
NOT_NULL(ppVertices);
if(numVertices == 2) {
Edge *pA = Edge::makeEdge();
if(*ppVertices[0] > *ppVertices[1]) {
ELEM_SWAP(ppVertices[0], ppVertices[1]);
}
pA->setOrg(ppVertices[0]);
pA->setDest(ppVertices[1]);
*ppLe = pA;
*ppRe = pA->Sym();
}
else if(numVertices == 3) {
Edge *pA = Edge::makeEdge(),
*pB = Edge::makeEdge(),
*pC = 0;
if(*ppVertices[0] > *ppVertices[1]) {
ELEM_SWAP(ppVertices[0], ppVertices[1]);
}
if(*ppVertices[1] > *ppVertices[2]) {
ELEM_SWAP(ppVertices[1], ppVertices[2]);
}
Edge::splice(pA->Sym(), pB);
pA->setOrg(ppVertices[0]);
pA->setDest(ppVertices[1]);
pB->setOrg(ppVertices[1]);
pB->setDest(ppVertices[2]);
REAL ccw = orient2d(ppVertices[0]->Pos(), ppVertices[1]->Pos(), ppVertices[2]->Pos());
if(ccw > 0) {
pC = Edge::connect(pB, pA);
*ppLe = pA;
*ppRe = pB->Sym();
}
else if(ccw < 0) {
pC = Edge::connect(pB, pA);
*ppLe = pC->Sym();
*ppRe = pC;
}
else {
*ppLe = pA;
*ppRe = pB->Sym();
}
}
else {
long middle = std::floor(numVertices/2);
Edge *pLdo = 0,
*pLdi = 0,
*pRdi = 0,
*pRdo = 0;
//These vertices are used for merging a horizontal cut
Vertex *pBotMax = 0, //highest vertex of bottom half
*pTopMin = 0, //lowest vertex of top half
*pMin = 0, //Lexicographically max vertex
*pMax = 0; //Lexicographically min vertex
//Find median partition by X or Y, depending on whether we're using a vertical cut
std::nth_element(ppVertices, ppVertices+middle, ppVertices+numVertices, useVertical ? Vertex::lessX : Vertex::lessY);
//Recursive calls
delaunay(ppVertices, middle, &pLdo, &pLdi, useAltCuts, useAltCuts ? !useVertical : useVertical);
delaunay(ppVertices+middle, numVertices - middle, &pRdi, &pRdo, useAltCuts, useAltCuts ? !useVertical : useVertical);
//Modify ldi be highest in bottom half and rdi to be lowest in top half
if(!useVertical) {
pBotMax = ppVertices[0];
pTopMin = ppVertices[middle];
pMin = (*ppVertices[0] < *ppVertices[middle]) ? ppVertices[0] : ppVertices[middle];
pMax = (*ppVertices[0] > *ppVertices[middle]) ? ppVertices[0] : ppVertices[middle];;
for(long i=1; i < middle; i++) {
if(*ppVertices[i] < *pMin) {
pMin = ppVertices[i];
}
else if(*ppVertices[i] > *pMax) {
pMax = ppVertices[i];
}
if(ppVertices[i]->gtY(*pBotMax)) {
pBotMax = ppVertices[i];
}
}
for(long i=middle+1; i < numVertices; i++) {
if(*ppVertices[i] < *pMin) {
pMin = ppVertices[i];
}
else if(*ppVertices[i] > *pMax) {
pMax = ppVertices[i];
}
if(ppVertices[i]->ltY(*pTopMin)) {
pTopMin = ppVertices[i];
}
}
pLdi = pBotMax->getCWHullEdge();
pRdi = pTopMin->getCCWHullEdge();
}
//Compute the lower common tangent of two sets of vertices
while (1) {
if(pLdi->leftOf(pRdi->Org())) {
pLdi = pLdi->Lnext();
}
else if(pRdi->rightOf(pLdi->Org())) {
pRdi = pRdi->Rprev();
}
else {
break;
}
}
// Create a first cross edge pBasel from pRdi.origin to pLdi.origin
Edge *pBasel = Edge::connect(pRdi->Sym(), pLdi);
if(pLdi->Org() == pLdo->Org()) {
pLdo = pBasel->Sym();
}
if(pRdi->Org() == pRdo->Org()) {
pRdo = pBasel;
}
//Merging two halves
while(1) {
//Locate the first Left point pLcand to be encou
Edge *pLcand = pBasel->Sym()->Onext();
bool leftFinished = !pLcand->valid(pBasel);
if(!leftFinished) {
while(incircle(pBasel->Dest()->Pos(),
pBasel->Org()->Pos(),
pLcand->Dest()->Pos(),
pLcand->Onext()->Dest()->Pos()) > 0) {
Edge *pT = pLcand->Onext();
Edge::deleteEdge(pLcand);
pLcand = pT;
}
}
//Symmetrically locate the first R point to be hit
Edge *pRcand = pBasel->Oprev();
bool rightFinished = !pRcand->valid(pBasel);
if(!rightFinished) {
while(incircle(pBasel->Dest()->Pos(),
pBasel->Org()->Pos(),
pRcand->Dest()->Pos(),
pRcand->Oprev()->Dest()->Pos()) > 0) {
Edge *pT = pRcand->Oprev();
Edge::deleteEdge(pRcand);
pRcand = pT;
}
}
//both are invalid, pBasel is upper common tangent
if(leftFinished && rightFinished) {
break;
}
//the next cross edge is to be connected to either pLcand.dest or pRcand.dest
if(leftFinished ||
(!rightFinished && incircle(pLcand->Dest()->Pos(),
pLcand->Org()->Pos(),
pRcand->Org()->Pos(),
pRcand->Dest()->Pos()) > 0)) {
pBasel = Edge::connect(pRcand, pBasel->Sym());
}
else {
pBasel = Edge::connect(pBasel->Sym(), pLcand->Sym());
}
}
//Modify pLdo and pRdo if we merging a horizontal cut
if(!useVertical) {
pLdo = pMin->getCCWHullEdge();
pRdo = pMax->getCWHullEdge();
}
*ppLe = pLdo;
*ppRe = pRdo;
}
return;
}
Edge *Subdivision::spoke(Vec2& x, Edge *e)
{
Triangle *new_faces[4];
int facedex = 0;
//
// NOTE: e is the edge returned by locate(x)
//
if ( (x == e->Org()) || (x == e->Dest()) ) {
// point is already in the mesh
//
#ifdef _INC_IOSTREAM
std::cerr << "WARNING: Tried to reinsert point: " << x << std::endl;
std::cerr << " org: " << e->Org() << std::endl;
std::cerr << " dest: " << e->Dest() << std::endl;
#endif
return NULL;
}
Edge *boundary_edge = NULL;
Triangle *lface = e->Lface();
lface->dontAnchor(e);
new_faces[facedex++] = lface;
if( onEdge(x,e) )
{
if( ccwBoundary(e) ) {
//
// e lies on the boundary
// Defer deletion until after new edges are added.
boundary_edge = e;
}
else {
Triangle *sym_lface = e->Sym()->Lface();
new_faces[facedex++] = sym_lface;
sym_lface->dontAnchor(e->Sym());
e = e->Oprev();
deleteEdge(e->Onext());
}
}
else
{
// x lies within the Lface of e
}
Edge *base = makeEdge(e->Org(), x.clone());
splice(base, e);
startingEdge = base;
do {
base = connect(e, base->Sym());
e = base->Oprev();
} while( e->Lnext() != startingEdge );
if( boundary_edge )
deleteEdge(boundary_edge);
// Update all the faces in our new spoked polygon.
// If point x on perimeter, then don't add an exterior face
base = boundary_edge ? startingEdge->Rprev() : startingEdge->Sym();
do {
if( facedex )
new_faces[--facedex]->reshape(base);
else
makeFace(base);
base = base->Onext();
} while( base != startingEdge->Sym() );
return startingEdge;
}