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vcglib/vcg/complex/algorithms/textcoord_optimization.h

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2011-04-01 18:25:49 +02:00
/****************************************************************************
* VCGLib o o *
* Visual and Computer Graphics Library o o *
* _ O _ *
* Copyright(C) 2004 \/)\/ *
* Visual Computing Lab /\/| *
* ISTI - Italian National Research Council | *
* \ *
* All rights reserved. *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License (http://www.gnu.org/licenses/gpl.txt) *
* for more details. *
* *
****************************************************************************/
/****************************************************************************
History
$Log: not supported by cvs2svn $
Revision 1.6 2007/02/02 04:11:00 tarini
added parameter theta (from conformal to equiareal) to AreaPresTextureOptimizer.
Improved feature lists (comments).
Revision 1.5 2007/02/02 01:39:58 tarini
added three general-utility global functions for texture coordinates: SmoothTextureCoords, IsFoldFree, MarkFolds (see descriptions)
Revision 1.4 2007/02/02 01:23:47 tarini
added a few general comments on AreaPreserving optimizer, recapping optimizer features.
Revision 1.3 2007/02/02 01:18:15 tarini
First version: general virtual class for texture optimizers. A subclass for area preservation.
****************************************************************************/
#ifndef __VCGLIB__TEXTCOOORD_OPTIMIZATION
#define __VCGLIB__TEXTCOOORD_OPTIMIZATION
#include <vcg/container/simple_temporary_data.h>
/*
SINGLE PATCH TEXTURE OPTIMIZATIONS
A set of classes to perform optimizations of disk->disk parametrization.
Requires texture coords to be defined per vertex (replicate seams).
*/
namespace vcg
{
namespace tri
{
/* Base class for all Texture Optimizers*/
template<class MESH_TYPE>
class TextureOptimizer{
protected:
MESH_TYPE &m;
SimpleTempData<typename MESH_TYPE::VertContainer, int > isFixed;
public:
/* Tpyes */
typedef MESH_TYPE MeshType;
typedef typename MESH_TYPE::VertexIterator VertexIterator;
typedef typename MESH_TYPE::FaceIterator FaceIterator;
typedef typename MESH_TYPE::VertexType VertexType;
typedef typename MESH_TYPE::FaceType FaceType;
typedef typename MESH_TYPE::ScalarType ScalarType;
/* Access functions */
const MeshType & Mesh() const {return m;}
MeshType & Mesh() {return m;}
/* Constructior */
TextureOptimizer(MeshType &_m):m(_m),isFixed(_m.vert){
assert(m.HasPerVertexTexture());
}
// initializes on current geometry
virtual void TargetCurrentGeometry()=0;
// performs an interation. Returns largest movement.
virtual ScalarType Iterate()=0;
// performs an iteration (faster, but it does not tell how close it is to stopping)
virtual void IterateBlind()=0;
// performs <steps> iteration
virtual ScalarType IterateN(int step){
for (int i=0; i<step-1; i++) {
this->IterateBlind();
}
if (step>1) return this->Iterate(); else return 0;
}
// performs iterations until convergence.
bool IterateUntilConvergence(ScalarType threshold=0.0001, int maxite=5000){
int i;
while (Iterate()>threshold) {
if (i++>maxite) return false;
}
return true;
}
// desctuctor: free temporary field
~TextureOptimizer(){
isFixed.Stop();
};
// set the current border as fixed (forced to stay in position during text optimization)
void SetBorderAsFixed(){
isFixed.Start();
for (VertexIterator v=m.vert.begin(); v!=m.vert.end(); v++) {
isFixed[v]=(v->IsB())?1:0;
}
}
// everything moves, no vertex must fixed during texture optimization)
void SetNothingAsFixed(){
isFixed.Start();
for (VertexIterator v=m.vert.begin(); v!=m.vert.end(); v++) {
isFixed[v]=0;
}
}
// fix a given vertex
void FixVertex(const VertexType *v, bool fix=true){
isFixed[v]=(fix)?1:0;
}
};
/*
AREA PRESERVING TEXTURE OPTIMIZATION
as in: Degener, P., Meseth, J., Klein, R.
"An adaptable surface parameterization method."
Proc. of the 12th International Meshing oundtable, 201<EFBFBD>213 [2003].
Features:
:) - Balances angle and area distortions (best results!).
:) - Can choose how to balance area and angle preservation (see SetTheta)
theta=0 -> pure conformal (use MIPS instead!)
theta=3 -> good balance between area and angle preservation
theta>3 -> care more about area than about angles
:( - Slowest method.
:( - Requires a fixed boundary, else expands forever in texture space (unless theta=0).
:( - Diverges in presence of flipped faces (unless theta=0).
:( - Requires a speed parameter to be set.
Speed too large => when close, bounces back and forth around minimum, w/o getting any closer.
Lower speed => longer convercence times
*/
template<class MESH_TYPE>
class AreaPreservingTextureOptimizer:public TextureOptimizer<MESH_TYPE>{
public:
/* Types */
typedef MESH_TYPE MeshType;
typedef typename MESH_TYPE::VertexIterator VertexIterator;
typedef typename MESH_TYPE::FaceIterator FaceIterator;
typedef typename MESH_TYPE::VertexType VertexType;
typedef typename MESH_TYPE::FaceType FaceType;
typedef typename MESH_TYPE::ScalarType ScalarType;
private:
typedef TextureOptimizer<MESH_TYPE> Super; // superclass (commodity)
// extra data per face: [0..3] -> cotangents. [4] -> area*2
SimpleTempData<typename MESH_TYPE::FaceContainer, Point4<ScalarType> > data;
SimpleTempData<typename MESH_TYPE::VertContainer, Point2<ScalarType> > sum;
ScalarType totArea;
ScalarType speed;
int theta;
public:
// constructor and destructor
AreaPreservingTextureOptimizer(MeshType &_m):Super(_m),data(_m.face),sum(_m.vert){
speed=0.001;
theta=3;
}
~AreaPreservingTextureOptimizer(){
data.Stop();
sum.Stop();
Super::isFixed.Stop();
}
void SetSpeed(ScalarType _speed){
speed=_speed;
}
ScalarType GetSpeed(){
return speed;
}
// sets the parameter theta:
// good parameters are in 1..3
// 0 = converge to pure conformal, ignore area preservation
// 3 = good balance between area and conformal
// >3 = area more important, angle preservation less important
void SetTheta(int _theta){
theta=_theta;
}
int GetTheta(){
return theta;
}
void IterateBlind(){
/* todo: do as iterate, but without */
Iterate();
}
ScalarType Iterate(){
ScalarType max; // max displacement
#define v0 (f->V0(i)->T().P())
#define v1 (f->V1(i)->T().P())
#define v2 (f->V2(i)->T().P())
for (VertexIterator v=Super::m.vert.begin(); v!=Super::m.vert.end(); v++) {
sum[v].SetZero();
}
ScalarType tot_proj_area=0;
for (FaceIterator f=Super::m.face.begin(); f!=Super::m.face.end(); f++) {
int i=0;
double area2 = ((v1-v0) ^ (v2-v0));
tot_proj_area+=area2;
}
double scale= 1.0; //tot_proj_area / tot_area ;
for (FaceIterator f=Super::m.face.begin(); f!=Super::m.face.end(); f++) {
int i=0; ScalarType area2 = ((v1-v0) ^ (v2-v0));
for (i=0; i<3; i++){
ScalarType
a = (v1-v0).Norm(),
b = ((v1-v0) * (v2-v0))/a,
c = area2 / a,
m0= data[f][i] / area2,
m1= data[f][(i+1)%3] / area2,
m2= data[f][(i+2)%3] / area2,
mx= (b-a)/area2,
my= c/area2, // 1.0/a
mA= data[f][3]/area2 * scale,
e = m0*((b-a)*(b-a)+c*c) + m1*(b*b+c*c) + m2*a*a, // as obvious
M1= mA + 1.0/mA,
M2= mA - 1.0/mA,
px= e*my,
py=-e*mx,
qx= m1*b+ m2*a,
qy= m1*c,
/* linear weightings
dx= (OMEGA) * (my * M2) +
(1-OMEGA) * ( px - 2.0*qx),
dy= (OMEGA) * (-mx * M2) +
(1-OMEGA) * ( py - 2.0*qy),*/
// exponential weighting
// 2d gradient
dx=// M1
//*M1 // ^ theta-1
pow(M1,theta-1)
*(px*(M1+ theta*M2) - 2.0*qx*M1),
dy=// M1
//*M1 // ^ theta-1
pow(M1,theta-1)
*(py*(M1+ theta*M2) - 2.0*qy*M1),
gy= dy/c,
gx= (dx - gy*b) / a;
// 3d gradient
sum[f->V(i)]+= ( (v1-v0) * gx + (v2-v0) * gy ) * data[f][3];
}
}
max=0; // max displacement
speed=0.001;
for (VertexIterator v=Super::m.vert.begin(); v!=Super::m.vert.end(); v++)
if ( !Super::isFixed[v] ) //if (!v->IsB())
{
ScalarType n=sum[v].Norm();
if ( n > 1 ) { sum[v]/=n; n=1.0;}
if ( n*speed<=0.1 ); {
v->T().P()-=(sum[v] * speed ) /** scale*/;
if (max<n) max=n;
}
//else rejected++;
}
return max;
#undef v0
#undef v1
#undef v2
//printf("rejected %d\n",rejected);
}
void TargetCurrentGeometry(){
Super::isFixed.Start();
data.Start();
sum.Start();
totArea=0;
for (FaceIterator f=Super::m.face.begin(); f!=Super::m.face.end(); f++) {
double area2 = ((f->V(1)->P() - f->V(0)->P() )^(f->V(2)->P() - f->V(0)->P() )).Norm();
totArea+=area2;
//if ( Super::isFixed[f->V1(0)] )
for (int i=0; i<3; i++){
data[f][i]=(
(f->V1(i)->P() - f->V0(i)->P() )*(f->V2(i)->P() - f->V0(i)->P() )
)/area2;
data[f][3]=area2;
}
}
}
};
/* texture coords general utility functions */
/*++++++++++++++++++++++++++++++++++++++++++*/
// returns false if any fold is present (faster than MarkFolds)
template<class MESH_TYPE>
bool IsFoldFree(MESH_TYPE &m){
assert(m.HasPerVertexTexture());
typedef typename MESH_TYPE::VertexType::TextureType::PointType PointType;
typedef typename MESH_TYPE::VertexType::TextureType::PointType::ScalarType ScalarType;
ScalarType lastsign=0;
for (typename MESH_TYPE::FaceIterator f=m.face.begin(); f!=m.face.end(); f++){
ScalarType sign=((f->V(1)->T().P()-f->V(0)->T().P()) ^ (f->V(2)->T().P()-f->V(0)->T().P()));
if (sign!=0) {
if (sign*lastsign<0) return false;
lastsign=sign;
}
}
return true;
}
// detects and marks folded faces, by setting their quality to 0 (or 1 otherwise)
// returns number of folded faces
template<class MESH_TYPE>
int MarkFolds(MESH_TYPE &m){
assert(m.HasPerVertexTexture());
assert(m.HasPerFaceQuality());
typedef typename MESH_TYPE::VertexType::TextureType::PointType PointType;
typedef typename MESH_TYPE::VertexType::TextureType::PointType::ScalarType ScalarType;
SimpleTempData<typename MESH_TYPE::FaceContainer, short> sign(m.face);
sign.Start(0);
// first pass, determine predominant sign
int npos=0, nneg=0;
ScalarType lastsign=0;
for (typename MESH_TYPE::FaceIterator f=m.face.begin(); f!=m.face.end(); f++){
ScalarType fsign=((f->V(1)->T().P()-f->V(0)->T().P()) ^ (f->V(2)->T().P()-f->V(0)->T().P()));
if (fsign<0) { sign[f]=-1; nneg++; }
if (fsign>0) { sign[f]=+1; npos++; }
}
// second pass, detect folded faces
int res=0;
short gsign= (nneg>npos)?-1:+1;
for (typename MESH_TYPE::FaceIterator f=m.face.begin(); f!=m.face.end(); f++){
if (sign[f]*gsign<0){
res++;
f->Q()=0;
} else f->Q()=1;
}
sign.Stop();
return res;
}
// Smooths texture coords.
// (can be useful to remove folds,
// e.g. these created when obtaining tecture coordinates after projections)
template<class MESH_TYPE>
void SmoothTextureCoords(MESH_TYPE &m){
assert(m.HasPerVertexTexture());
typedef typename MESH_TYPE::VertexType::TextureType::PointType PointType;
SimpleTempData<typename MESH_TYPE::VertContainer, int> div(m.vert);
SimpleTempData<typename MESH_TYPE::VertContainer, PointType > sum(m.vert);
div.Start();
sum.Start();
for (typename MESH_TYPE::VertexIterator v=m.vert.begin(); v!=m.vert.end(); v++) {
sum[v].SetZero();
div[v]=0;
}
for (typename MESH_TYPE::FaceIterator f=m.face.begin(); f!=m.face.end(); f++){
div[f->V(0)] +=2; sum[f->V(0)] += f->V(2)->T().P(); sum[f->V(0)] += f->V(1)->T().P();
div[f->V(1)] +=2; sum[f->V(1)] += f->V(0)->T().P(); sum[f->V(1)] += f->V(2)->T().P();
div[f->V(2)] +=2; sum[f->V(2)] += f->V(1)->T().P(); sum[f->V(2)] += f->V(0)->T().P();
}
for (typename MESH_TYPE::VertexIterator v=m.vert.begin(); v!=m.vert.end(); v++) // if (!v->IsB())
{
if (v->div>0) {
v->T().P() = sum[v]/div[v];
}
}
div.Stop();
sum.Stop();
}
} } // End namespace vcg::tri
#endif // __VCGLIB__TEXTCOOORD_OPTIMIZATION