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vcglib/vcg/complex/trimesh/bitquad_creation.h

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//#include <vcg/complex/trimesh/bitquad_support.h>
/** BIT-QUAD creation support:
a collection of methods that,
starting from a triangular mesh, will create your quad-pure or quad-domainant mesh.
They all require:
- per face Q, and FF connectivity, 2-manyfold meshes,
- and tri- or quad- meshes (no penta, etc) (if in need, use MakeBitTriOnly)
[ list of available methods: ]
void MakePureByRefine(Mesh &m)
- adds a vertex for each tri or quad present
- thus, miminal complexity increase is the mesh is quad-dominant already
- old non-border edges are made faux
- never fails
void MakePureByCatmullClark(MeshType &m)
- adds a vertex in each (non-faux) edge.
- twice complexity increase w.r.t. "ByRefine" method.
- preserves edges: old edges are still edges
- never fails
bool MakePureByFlip(MeshType &m [, int maxdist] )
- does not increase # vertices, just flips edges
- call in a loop until it returns true (temporary hack)
- fails if number of triangle is odd (only happens in open meshes)
- add "StepByStep" to method name if you want it to make a single step (debugging purposes)
bool MakeTriEvenBySplit(MeshType& m)
bool MakeTriEvenByDelete(MeshType& m)
- two simple variants that either delete or split *at most one* border face
so that the number of tris will be made even. Return true if it did it.
- useful to use the previous method, when mesh is still all triangle
void MakeDominant(MeshType &m, int level)
- just merges traingle pairs into quads, trying its best
- various heuristic available, see descr. for parameter "level"
- provides good starting point for make-Quad-Only methods
- uses an ad-hoc measure for "quad quality" (which is hard-wired, for now)
void MakeBitTriOnly(MeshType &m)
- inverse process: returns to tri-only mesh
(more info in comments before each method)
*/
namespace vcg{namespace tri{
template <class _MeshType>
class BitQuadCreation{
public:
typedef _MeshType MeshType;
typedef typename MeshType::ScalarType ScalarType;
typedef typename MeshType::CoordType CoordType;
typedef typename MeshType::FaceType FaceType;
typedef typename MeshType::FaceType* FaceTypeP;
typedef typename MeshType::VertexType VertexType;
typedef typename MeshType::FaceIterator FaceIterator;
typedef typename MeshType::VertexIterator VertexIterator;
typedef BitQuad<MeshType> BQ; // static class to make basic quad operations
// helper function:
// given a triangle, merge it with its best neightboord to form a quad
template <bool override>
static void selectBestDiag(FaceType *fi){
if (!override) {
if (fi->IsAnyF()) return;
}
// select which edge to make faux (if any)...
int whichEdge = -1;
ScalarType bestScore = fi->Q();
whichEdge=-1;
for (int k=0; k<3; k++){
// todo: check creases? (continue if edge k is a crease)
if (!override) {
if (fi->FFp(k)->IsAnyF()) continue;
}
if (fi->FFp(k)==fi) continue; // never make a border faux
ScalarType score = BQ::quadQuality( &*fi, k );
if (override) {
// don't override anyway iff other face has a better match
if (score < fi->FFp(k)->Q()) continue;
}
if (score>bestScore) {
bestScore = score;
whichEdge = k;
}
}
// ...and make it faux
if (whichEdge>=0) {
//if (override && fi->FFp(whichEdge)->IsAnyF()) {
// new score is the average of both scores
// fi->Q() = fi->FFp(whichEdge)->Q() = ( bestScore + fi->FFp(whichEdge)->Q() ) /2;
//} else {
//}
if (override) {
// clear any faux edge of the other face
for (int k=0; k<3; k++)
if (fi->FFp(whichEdge)->IsF(k)) {
fi->FFp(whichEdge)->ClearF(k);
fi->FFp(whichEdge)->FFp(k)->ClearF( fi->FFp(whichEdge)->FFi(k) );
fi->FFp(whichEdge)->FFp(k)->Q()=0.0; // other face's ex-buddy is now single and sad :(
}
// clear all faux edges of this face...
for (int k=0; k<3; k++)
if (fi->IsF(k)) {
fi->ClearF(k);
fi->FFp(k)->ClearF( fi->FFi(k) );
fi->FFp(k)->Q()= 0.0; // my ex-buddy is now sad
}
}
// set (new?) quad
fi->SetF(whichEdge);
fi->FFp(whichEdge)->SetF( fi->FFi(whichEdge) );
fi->Q() = fi->FFp(whichEdge)->Q() = bestScore;
}
}
// helper funcion:
// a pass though all triangles to merge triangle pairs into quads
template <bool override> // override previous decisions?
static void MakeDominantPass(MeshType &m){
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) {
selectBestDiag<override>(&(*fi));
}
}
// make tri count even by splitting a single triangle...
static bool MakeTriEvenBySplit(MeshType& m){
if (m.fn%2==0) return false; // it's already Even
assert(0); // todo!
}
// make tri count even by delete...
static bool MakeTriEvenByDelete(MeshType& m)
{
if (m.fn%2==0) return false; // it's already Even
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) {
for (int k=0; k<3; k++) {
if (fi->FFp(k) == &* fi) {
// mark the two old neight as border and not faux
for (int h=1; h<3; h++) {
int kh=(k+h)%3;
int j = fi->FFi( kh );
FaceType *f = fi->FFp(kh);
if (f != &* fi) {
f->FFp( j ) = f;
f->FFi( j ) = j;
f->ClearF(j);
}
}
// delete found face
Allocator<MeshType>::DeleteFace(m,*fi);
return true;
}
}
}
assert(0); // no border face found? then how could the number of tri be Odd?
return true;
}
/**
Given a mesh, makes it bit trianglular (makes all edges NOT faux)
*/
static void MakeBitTriOnly(MeshType &m){
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) {
fi->ClearAllF();
}
}
/** given a quad-and-tree mesh, enforces the "faux edge is 2nd edge" convention.
* Requires (and updates): FV and FF structure
* Updates: faux flags
* Updates: per wedge attributes, if any
* Other connectivity structures, and per edge and per wedge flags are ignored
*/
static bool MakeBitTriQuadConventional(MeshType &m){
assert(0); // todo
}
/* returns true if mesh is a "conventional" quad mesh.
I.e. if it is all quads, with third edge faux fora all triangles*/
static bool IsBitTriQuadConventional(MeshType &m){
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) {
if (fi->IsAnyF())
if ( fi->Flags() & ( FaceType::FAUX012 ) != FaceType::FAUX2 ) {
return false;
}
}
return true;
}
/**
makes any mesh quad only by refining it so that a quad is created over all
previous diags
requires that the mesh is made only of quads and tris.
*/
static void MakePureByRefine(MeshType &m){
// todo: update VF connectivity if present
int ev = 0; // EXTRA vertices (times 2)
int ef = 0; // EXTRA faces
// first pass: count triangles to be added
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) {
int k=0; // number of borders
if (fi->FFp(0) == &*fi) k++;
if (fi->FFp(1) == &*fi) k++;
if (fi->FFp(2) == &*fi) k++;
if (!fi->IsAnyF()) {
// it's a triangle
if (k==0) // add a vertex in the center of the face, splitting it in 3
{ ev+=2; ef+=2; }
if (k==1) // add a vertex in the border edge, splitting it in 2
{ }
if (k==2) // do nothing, just mark the non border edge as faux
{ }
if (k==3) // disconnected single triangle (all borders): make one edge as faus
{ }
}
else {
// assuming is a quad (not a penta, etc), i.e. only one faux
// add a vertex in the center of the faux edge, splitting the face in 2
ev+=1; ef+=1;
assert(k!=3);
}
}
assert(ev%2==0); // should be even by now
ev/=2; // I was counting each of them twice
int originalFaceNum = m.fn;
FaceIterator nfi = tri::Allocator<MeshType>::AddFaces(m,ef);
VertexIterator nvi = tri::Allocator<MeshType>::AddVertices(m,ev);
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) fi->ClearV();
// second pass: add faces and vertices
int nsplit=0; // spits to be done on border in the third pass
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD() && !fi->IsV() ) {
fi->SetV();
if (!fi->IsAnyF()) {
// it's a triangle
int k=0; // number of borders
if (fi->FFp(0) == &*fi) k++;
if (fi->FFp(1) == &*fi) k++;
if (fi->FFp(2) == &*fi) k++;
if (k==0) // add a vertex in the center of the face, splitting it in 3
{
assert(nvi!=m.vert.end());
VertexType *nv = &*nvi; nvi++;
*nv = *fi->V0( 0 ); // lazy: copy everything from the old vertex
nv->P() = ( fi->V(0)->P() + fi->V(1)->P() + fi->V(2)->P() ) /3.0;
FaceType *fa = &*fi;
FaceType *fb = &*nfi; nfi++;
FaceType *fc = &*nfi; nfi++;
*fb = *fc = *fa; // lazy: copy everything from the old faces
fa->V(0) = nv;
fb->V(1) = nv;
fc->V(2) = nv;
assert( fa->FFp(1)->FFp(fa->FFi(1)) == fa );
/* */fb->FFp(2)->FFp(fb->FFi(2)) = fb;
/* */fc->FFp(0)->FFp(fc->FFi(0)) = fc;
fa->FFp(0) = fc; fa->FFp(2) = fb; fa->FFi(0) = fa->FFi(2) = 1;
fb->FFp(1) = fa; fb->FFp(0) = fc; fb->FFi(0) = fb->FFi(1) = 2;
fc->FFp(1) = fa; fc->FFp(2) = fb; fc->FFi(1) = fc->FFi(2) = 0;
if (fb->FFp(2)==fa) fb->FFp(2)=fb; // recover border status
if (fc->FFp(0)==fa) fc->FFp(0)=fc;
fa->ClearAllF();
fb->ClearAllF();
fc->ClearAllF();
fa->SetF(1);
fb->SetF(2);
fc->SetF(0);
fa->SetV();fb->SetV();fc->SetV();
}
if (k==1) { // make a border face faux, anf other two as well
fi->SetF(0);
fi->SetF(1);
fi->SetF(2);
nsplit++;
}
if (k==2) // do nothing, just mark the non border edge as faux
{
fi->ClearAllF();
for (int w=0; w<3; w++) if (fi->FFp(w) != &*fi) fi->SetF(w);
}
if (k==3) // disconnected single triangle (all borders): use catmull-clark (tree vertices, split it in 6
{
fi->ClearAllF();
fi->SetF(2);
nsplit++;
}
}
else {
// assuming is a part of quad (not a penta, etc), i.e. only one faux
FaceType *fa = &*fi;
int ea2 = BQ::FauxIndex(fa); // index of the only faux edge
FaceType *fb = fa->FFp(ea2);
int eb2 = fa->FFi(ea2);
assert(fb->FFp(eb2)==fa) ;
assert(fa->IsF(ea2));
//assert(fb->IsF(eb2)); // reciprocal faux edge
int ea0 = (ea2+1) %3;
int ea1 = (ea2+2) %3;
int eb0 = (eb2+1) %3;
int eb1 = (eb2+2) %3;
// create new vert in center of faux edge
assert(nvi!=m.vert.end());
VertexType *nv = &*nvi; nvi++;
*nv = * fa->V0( ea2 );
nv->P() = ( fa->V(ea2)->P() + fa->V(ea0)->P() ) /2.0;
// split faces: add 2 faces (one per side)
assert(nfi!=m.face.end());
FaceType *fc = &*nfi; nfi++;
assert(nfi!=m.face.end());
FaceType *fd = &*nfi; nfi++;
*fc = *fa;
*fd = *fb;
fa->V(ea2) = fc->V(ea0) =
fb->V(eb2) = fd->V(eb0) = nv ;
fa->FFp(ea1)->FFp( fa->FFi(ea1) ) = fc;
fb->FFp(eb1)->FFp( fb->FFi(eb1) ) = fd;
fa->FFp(ea1) = fc ; fa->FFp(ea2) = fd;
fa->FFi(ea1) = ea0; fa->FFi(ea2) = eb2;
fb->FFp(eb1) = fd ; fb->FFp(eb2) = fc;
fb->FFi(eb1) = eb0; fb->FFi(eb2) = ea2;
fc->FFp(ea0) = fa ; fc->FFp(ea2) = fb;
fc->FFi(ea0) = ea1; fc->FFi(ea2) = eb2;
fd->FFp(eb0) = fb ; fd->FFp(eb2) = fa;
fd->FFi(eb0) = eb1; fd->FFi(eb2) = ea2;
// detect boundaries
bool ba = fa->FFp(ea0)==fa;
bool bc = fc->FFp(ea1)==fa;
bool bb = fb->FFp(eb0)==fb;
bool bd = fd->FFp(eb1)==fb;
if (bc) fc->FFp(ea1)=fc; // repristinate boundary status
if (bd) fd->FFp(eb1)=fd; // of new faces
fa->SetV();
fb->SetV();
fc->SetV();
fd->SetV();
fa->ClearAllF();
fb->ClearAllF();
fc->ClearAllF();
fd->ClearAllF();
fa->SetF( ea0 );
fb->SetF( eb0 );
fc->SetF( ea1 );
fd->SetF( eb1 );
// fix faux mesh boundary... if two any consecutive, merge it in a quad
if (ba&&bc) {
fa->ClearAllF(); fa->SetF(ea1);
fc->ClearAllF(); fc->SetF(ea0);
ba = bc = false;
}
if (bc&&bb) {
fc->ClearAllF(); fc->SetF(ea2);
fb->ClearAllF(); fb->SetF(eb2);
bc = bb = false;
}
if (bb&&bd) {
fb->ClearAllF(); fb->SetF(eb1);
fd->ClearAllF(); fd->SetF(eb0);
bb = bd = false;
}
if (bd&&ba) {
fd->ClearAllF(); fd->SetF(eb2);
fa->ClearAllF(); fa->SetF(ea2);
bd = ba = false;
}
// remaninig boudaries will be fixed by splitting in the last pass
if (ba) nsplit++;
if (bb) nsplit++;
if (bc) nsplit++;
if (bd) nsplit++;
}
}
assert(nfi==m.face.end());
assert(nvi==m.vert.end());
// now and there are no tris left, but there can be faces with ONE edge border & faux ()
// last pass: add vertex on faux border faces... (if any)
if (nsplit>0) {
FaceIterator nfi = tri::Allocator<MeshType>::AddFaces(m,nsplit);
VertexIterator nvi = tri::Allocator<MeshType>::AddVertices(m,nsplit);
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) {
FaceType* fa = &*fi;
int ea2 = -1; // border and faux face (if any)
if (fa->FFp(0)==fa && fa->IsF(0) ) ea2=0;
if (fa->FFp(1)==fa && fa->IsF(1) ) ea2=1;
if (fa->FFp(2)==fa && fa->IsF(2) ) ea2=2;
if (ea2 != -1) { // ea2 edge is naughty (border AND faux)
int ea0 = (ea2+1) %3;
int ea1 = (ea2+2) %3;
// create new vert in center of faux edge
VertexType *nv = &*nvi; nvi++;
*nv = * fa->V0( ea2 );
nv->P() = ( fa->V(ea2)->P() + fa->V(ea0)->P() ) /2.0;
// split face: add 1 face
FaceType *fc = &*nfi; nfi++;
*fc = *fa;
fa->V(ea2) = fc->V(ea0) = nv ;
fc->FFp(ea2) = fc;
fa->FFp(ea1)->FFp( fa->FFi(ea1) ) = fc;
fa->FFp(ea1) = fc ;
fa->FFi(ea1) = ea0;
fc->FFp(ea0) = fa ; fc->FFp(ea2) = fc;
fc->FFi(ea0) = ea1;
if (fc->FFp(ea1)==fa) fc->FFp(ea1)=fc; // recover border status
assert(fa->IsF(ea0) == fa->IsF(ea1) );
bool b = fa->IsF(ea1);
fa->ClearAllF();
fc->ClearAllF();
if (b) {
fa->SetF( ea0 );
fc->SetF( ea1 );
} else {
fa->SetF( ea1 );
fc->SetF( ea0 );
}
}
}
}
}
// uses Catmull Clark to enforce quad only meshes
// each old edge (but not faux) is split in two.
static void MakePureByCatmullClark(MeshType &m){
MakePureByRefine(m);
MakePureByRefine(m);
// et-voil<69>!!!
}
// Helper funcion:
// marks edge distance froma a given face.
// Stops at maxDist or at the distance when a triangle is found
static FaceType * MarkEdgeDistance(MeshType &m, FaceType *f, int maxDist){
assert(MeshType::HasPerFaceQuality());
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!f->IsD()) {
fi->Q()=maxDist;
}
FaceType * firstTriangleFound = NULL;
f->Q() = 0;
std::vector<FaceType*> stack;
int stackPos=0;
stack.push_back(f);
while ( stackPos<stack.size() ) {
FaceType *f = stack[stackPos++];
for (int k=0; k<3; k++) {
FaceType *fk = f->FFp(k);
int fq = int(f->Q()) + ( ! f->IsF(k) );
if (fk->Q()> fq && fq <= maxDist) {
if (!fk->IsAnyF()) { firstTriangleFound = fk; maxDist = fq;}
fk->Q() = fq;
stack.push_back(fk);
}
}
}
return firstTriangleFound;
}
/*
given a tri-quad mesh,
uses edge rotates to make a tri move toward another tri and to merges them into a quad.
Retunrs number of surviving triangles (0, or 1), or -1 if not done yet.
StepbyStep: makes just one step!
use it in a loop as long as it returns 0 or 1.
maxdist is the maximal edge distance where to look for a companion triangle
*/
static int MakePureByFlipStepByStep(MeshType &m, int maxdist=10000, int restart=false){
static FaceType *ta, *tb; // faces to be matched into a quad
static int step = 0; // hack
if (restart) { step=0; return false; }
if (step==0) {
// find a triangular face ta
ta = NULL;
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) if (!fi->IsD()) {
if (!fi->IsAnyF()) { ta=&*fi; break; }
}
if (!ta) return 0; // success: no triangle left (done?)
tb = MarkEdgeDistance(m,ta,maxdist);
if (!tb) return 1; // fail: no matching triagle found (increase maxdist?)
step=1;
} else {
int marriageEdge=-1;
bool done = false;
while (!done) {
int bestScore = int(tb->Q());
int edge = -1;
bool mustDoFlip;
// select which edge to use
for (int k=0; k<3; k++) {
if (tb->FFp(k) == tb) continue; // border
FaceType* tbk = tb->FFp(k);
if (!tbk->IsAnyF()) {done=true; marriageEdge=k; break; } // found my match
int back = tb->FFi(k);
int faux = BQ::FauxIndex(tbk);
int other = 3-back-faux;
int scoreA = int(tbk->FFp(other)->Q());
FaceType* tbh = tbk->FFp(faux);
int fauxh = BQ::FauxIndex(tbh);
int scoreB = int(tbh->FFp( (fauxh+1)%3 )->Q());
int scoreC = int(tbh->FFp( (fauxh+2)%3 )->Q());
int scoreABC = std::min( scoreC, std::min( scoreA, scoreB ) );
if (scoreABC<bestScore) {
bestScore = scoreABC;
edge = k;
mustDoFlip = !(scoreB == scoreABC || scoreC == scoreABC);
}
}
if (done) break;
// use that edge to proceed
if (mustDoFlip) {
BQ::FlipDiag( *(tb->FFp(edge)) );
}
FaceType* next = tb->FFp(edge)->FFp( BQ::FauxIndex(tb->FFp(edge)) );
// create new edge
next->ClearAllF();
tb->FFp(edge)->ClearAllF();
// dissolve old edge
tb->SetF(edge);
tb->FFp(edge)->SetF( tb->FFi(edge) );
tb->FFp(edge)->Q() = tb->Q();
tb = next;
break;
}
if (marriageEdge!=-1) {
// consume the marriage (two tris = one quad)
assert(!(tb->IsAnyF()));
assert(!(tb->FFp(marriageEdge)->IsAnyF()));
tb->SetF(marriageEdge);
tb->FFp(marriageEdge)->SetF(tb->FFi(marriageEdge));
step=0;
}
}
return -1; // not done yet
}
/*
given a tri-quad mesh,
uses edge rotates to make a tri move toward another tri and to merges them into a quad.
- maxdist is the maximal edge distance where to look for a companion triangle
- retunrs true if all triangles are merged (always, unless they are odd, or maxdist not enough).
*/
static bool MakePureByFlip(MeshType &m, int maxdist=10000)
{
MakePureByFlipStepByStep(m, maxdist, true); // restart
int res=-1;
while (res==-1) res = MakePureByFlipStepByStep(m, maxdist);
return res==0;
}
/**
given a triangle mesh, makes it quad dominant by merging triangle pairs into quads
various euristics:
level = 0: maximally greedy. Leaves fewest triangles
level = 1: smarter: leaves more triangles, but makes better quality quads
level = 2: even more so (marginally)
*/
static void MakeDominant(MeshType &m, int level){
assert(MeshType::HasPerFaceQuality());
assert(MeshType::HasPerFaceFlags());
for (FaceIterator fi = m.face.begin(); fi!=m.face.end(); fi++) {
fi->ClearAllF();
fi->Q() = 0;
}
MakeDominantPass<false> (m);
if (level>0) MakeDominantPass<true> (m);
if (level>1) MakeDominantPass<true> (m);
if (level>0) MakeDominantPass<false> (m);
}
};
}} // end namespace vcg::tri
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