https://github.com/HTDerekLiu/surface_multigrid_code
Tip revision: a827578755d864df68b103c71048c7da7a00ce59 authored by HTDerekLiu on 09 August 2021, 18:36:04 UTC
add a faster example
add a faster example
Tip revision: a827578
SSP_collapse_edge.cpp
#include "SSP_collapse_edge.h"
#include <igl/circulation.h>
#include <igl/edge_collapse_is_valid.h>
#include <always_try_never_care.h>
#include <vector>
#include <math.h>
#include <fstream>
void printVector(
std::vector<int> vec)
{
for(int ii = 0; ii < vec.size(); ii++)
std::cout << vec[ii] << ", ";
std::cout << "\n";
}
bool SSP_collapse_edge(
const int e,
const Eigen::RowVectorXd & p,
/*const*/ std::vector<int> & Nsv,
const std::vector<int> & Nsf,
/*const*/ std::vector<int> & Ndv,
const std::vector<int> & Ndf,
Eigen::MatrixXd & V,
Eigen::MatrixXi & F,
Eigen::MatrixXi & E,
Eigen::VectorXi & EMAP,
Eigen::MatrixXi & EF,
Eigen::MatrixXi & EI,
int & a_e1,
int & a_e2,
int & a_f1,
int & a_f2,
std::vector<single_collapse_data> & decInfo,
std::vector<std::vector<int>> & decIM,
single_collapse_data & data,
Eigen::VectorXi & FIdx_onering_pre)
{
// Assign this to 0 rather than, say, -1 so that deleted elements will get
// draw as degenerate elements at vertex 0 (which should always exist and
// never get collapsed to anything else since it is the smallest index)
using namespace Eigen;
using namespace std;
using namespace igl;
const int eflip = E(e,0)>E(e,1);
// source and destination
const int s = eflip?E(e,1):E(e,0);
const int d = eflip?E(e,0):E(e,1);
// if(!edge_collapse_is_valid(Nsv,Ndv))
// {
// return false;
// }
vector<int> Nsv_alec = Nsv;
vector<int> Ndv_alec = Ndv;
if(!igl::edge_collapse_is_valid(Nsv_alec,Ndv_alec))
{
return false;
}
// ===================
// Derek modifications:
// ===================
if ((decInfo.size()+1) % 100000 == 0)
cout << "#collapses: " << decInfo.size()+1 << endl;
bool isDebug = false;
bool verbose = false;
int vi = s;
int vj = d;
// int vi = E(e,0); // last one of Nsv
// int vj = E(e,1); // last one of Ndv
// {
// if (vj < vi)
// {
// int vtmp = vi;
// vi = vj;
// vj = vtmp;
// }
// }
// cout << "finish fliping Nsv, Ndv\n";
// VectorXi FIdx_onering_pre, FIdx_onering_post;
VectorXi FIdx_onering_post;
MatrixXi F_onering_pre, F_onering_post;
{
// PROFC_NODE("dec: get 1-ring mesh");
bool validEdge = get_collapse_onering_faces(V,F,vi,vj,Nsf,Ndf,
FIdx_onering_pre,FIdx_onering_post,F_onering_pre,F_onering_post);
if (validEdge == false)
{
return false;
}
}
// get local mesh (V_pre, FUV_pre)
MatrixXd V_pre;
MatrixXi FUV_pre;
VectorXi subsetVIdx;
{
// PROFC_NODE("dec: get local V");
std::map<int, int> IM;
remove_unreferenced_lessF(V,F_onering_pre,V_pre,FUV_pre,IM,subsetVIdx);
}
// get constraint vertices b for pre flattening
// cout << "get constraint vertices b for pre flattening" << endl;
VectorXi b(2);
{
// find vi (b(0)) and vj (b(1)) in subsetVIdx
for (int ii=0; ii<subsetVIdx.size(); ii++){
if (subsetVIdx(ii) == vi)
b(0) = ii;
else if (subsetVIdx(ii) == vj)
b(1) = ii;
}
assert(b(0) < b(1));
}
// Post collapse:
// get V_post
MatrixXd V_post = V_pre;
V_post.row(b(0)) = p;
// get FUV_post
MatrixXi FUV_post;
VectorXi FUV_pre_keep;
{
// PROFC_NODE("dec: get local F");
get_post_faces(FUV_pre, b(0), b(1), FUV_pre_keep, FUV_post);
}
if (isDebug)
{
igl::writeOBJ("V_pre.obj", V_pre, FUV_pre);
igl::writeOBJ("V_post.obj", V_post, FUV_post);
}
// get local Nsv, Ndv
vector<int> Nsv_local, Ndv_local;
{
// PROFC_NODE("dec: get local Nv");
int infVIdx = V.rows() - 1;
// get local Nsv
Nsv_local = Nsv;
for (int ii=0; ii<Nsv_local.size(); ii++)
{
if (Nsv_local[ii] == infVIdx)
Nsv_local[ii] = -1;
else
{
for (int jj=0; jj<subsetVIdx.size(); jj++)
{
if (Nsv_local[ii] == subsetVIdx(jj))
Nsv_local[ii] = jj;
}
}
}
// get local Ndv
Ndv_local = Ndv;
for (int ii=0; ii<Ndv_local.size(); ii++)
{
if (Ndv_local[ii] == infVIdx)
Ndv_local[ii] = -1;
else
{
for (int jj=0; jj<subsetVIdx.size(); jj++)
{
if (Ndv_local[ii] == subsetVIdx(jj))
Ndv_local[ii] = jj;
}
}
}
}
// joint flattening
MatrixXd UV_pre, UV_post;
{
// PROFC_NODE("dec: joint lscm");
bool isValid = true;
isValid = joint_lscm(V_pre, FUV_pre, V_post, FUV_post, b(0), b(1), Nsv_local, Ndv_local, UV_pre, UV_post);
if (!isValid)
return false;
}
{
if (FUV_pre.rows() <= 2)
{
if (verbose)
cout << "too less faces" << endl;
return false;
}
}
// {
// PROFC_NODE("check triangle quality");
// // check UV_pre triangle quality
// for (int ii=0; ii<FIdx_onering_post.size(); ii++)
// {
// int fIdx = FIdx_onering_post(ii);
// int v0 = F(fIdx,0);
// int v1 = F(fIdx,1);
// int v2 = F(fIdx,2);
// double l0 = (V.row(v0) - V.row(v1)).norm();
// double l1 = (V.row(v1) - V.row(v2)).norm();
// double l2 = (V.row(v2) - V.row(v0)).norm();
// double x = (l0+l1+l2) / 2;
// double delta = sqrt(x * (x-l0) * (x-l1) * (x-l2));
// double triQ = 4 * sqrt(3) * delta / (l0*l0 + l1*l1 + l2*l2);
// if (triQ < triangleQualityThreshold || isnan(triQ))
// {
// if (verbose)
// cout << "bad triangle quality" << endl;
// return false;
// }
// }
// }
// // TODO: check 3D triangle normal flip
// if (collapsed == true)
// {
// PROFC_NODE("check 3D face flip");
// MatrixXd FN_pre, FN_post;
// igl::per_face_normals(V_pre,FUV_pre,FN_pre);
// igl::per_face_normals(V_post,FUV_post,FN_post);
// for (int ii=0; ii<FUV_pre_keep.size(); ii++)
// {
// double dotProd = FN_pre.row(FUV_pre_keep(ii)).dot(FN_post.row(ii));
// // cout << "dot product: " << dotProd << endl;
// if (dotProd < 0.7)
// {
// // if (verbose)
// // {
// cout << "3D face flip" << endl;
// // }
// collapsed = false;
// break;
// }
// }
// }
// if (verbose)
// cout << "finish collapse checks\n";
// single_collapse_data data;
{
data.b.resize(b.size());
data.b = b;
data.subsetVIdx.resize(subsetVIdx.size());
data.subsetVIdx = subsetVIdx;
data.V_pre.resize(V_pre.rows(), V_pre.cols()); data.V_pre = V_pre; // could be deleted
data.V_post.resize(V_post.rows(), V_post.cols()); data.V_post = V_post; // could be deleted
data.Nsv = Nsv_local; // could be deleted
data.Ndv = Ndv_local; // could be deleted
data.UV_pre.resize(UV_pre.rows(), UV_pre.cols()); data.UV_pre = UV_pre;
data.UV_post.resize(UV_post.rows(), UV_post.cols()); data.UV_post = UV_post;
data.FUV_pre.resize(FUV_pre.rows(), FUV_pre.cols()); data.FUV_pre = FUV_pre;
data.FUV_post.resize(FUV_post.rows(), FUV_post.cols()); data.FUV_post = FUV_post;
data.FIdx_pre = FIdx_onering_pre;
data.FIdx_post = FIdx_onering_post;
}
// ===================
// Derek modifications end
// ===================
// OVERLOAD: caller may have just computed this
//
// Important to grab neighbors of d before monkeying with edges
const std::vector<int> & nV2Fd = (!eflip ? Nsf : Ndf);
// The following implementation strongly relies on s<d
assert(s<d && "s should be less than d");
// move source and destination to placement
V.row(s) = p;
V.row(d) = p;
// Helper function to replace edge and associate information with NULL
const auto & kill_edge = [&E,&EI,&EF](const int e)
{
E(e,0) = IGL_COLLAPSE_EDGE_NULL;
E(e,1) = IGL_COLLAPSE_EDGE_NULL;
EF(e,0) = IGL_COLLAPSE_EDGE_NULL;
EF(e,1) = IGL_COLLAPSE_EDGE_NULL;
EI(e,0) = IGL_COLLAPSE_EDGE_NULL;
EI(e,1) = IGL_COLLAPSE_EDGE_NULL;
};
// update edge info
// for each flap
const int m = F.rows();
for(int side = 0;side<2;side++)
{
const int f = EF(e,side);
const int v = EI(e,side);
const int sign = (eflip==0?1:-1)*(1-2*side);
// next edge emanating from d
const int e1 = EMAP(f+m*((v+sign*1+3)%3));
// prev edge pointing to s
const int e2 = EMAP(f+m*((v+sign*2+3)%3));
assert(E(e1,0) == d || E(e1,1) == d);
assert(E(e2,0) == s || E(e2,1) == s);
// face adjacent to f on e1, also incident on d
const bool flip1 = EF(e1,1)==f;
const int f1 = flip1 ? EF(e1,0) : EF(e1,1);
assert(f1!=f);
assert(F(f1,0)==d || F(f1,1)==d || F(f1,2) == d);
// across from which vertex of f1 does e1 appear?
const int v1 = flip1 ? EI(e1,0) : EI(e1,1);
// Kill e1
kill_edge(e1);
// Kill f
F(f,0) = IGL_COLLAPSE_EDGE_NULL;
F(f,1) = IGL_COLLAPSE_EDGE_NULL;
F(f,2) = IGL_COLLAPSE_EDGE_NULL;
// map f1's edge on e1 to e2
assert(EMAP(f1+m*v1) == e1);
EMAP(f1+m*v1) = e2;
// side opposite f2, the face adjacent to f on e2, also incident on s
const int opp2 = (EF(e2,0)==f?0:1);
assert(EF(e2,opp2) == f);
EF(e2,opp2) = f1;
EI(e2,opp2) = v1;
// remap e2 from d to s
E(e2,0) = E(e2,0)==d ? s : E(e2,0);
E(e2,1) = E(e2,1)==d ? s : E(e2,1);
if(side==0)
{
a_e1 = e1;
a_f1 = f;
}else
{
a_e2 = e1;
a_f2 = f;
}
}
// finally, reindex faces and edges incident on d. Do this last so asserts
// make sense.
//
// Could actually skip first and last, since those are always the two
// collpased faces. Nah, this is handled by (F(f,v) == d)
//
// Don't attempt to use Nde,Nse here because EMAP has changed
{
int p1 = -1;
for(auto f : nV2Fd)
{
for(int v = 0;v<3;v++)
{
if(F(f,v) == d)
{
const int e1 = EMAP(f+m*((v+1)%3));
const int flip1 = (EF(e1,0)==f)?1:0;
assert( E(e1,flip1) == d || E(e1,flip1) == s);
E(e1,flip1) = s;
const int e2 = EMAP(f+m*((v+2)%3));
// Skip if we just handled this edge (claim: this will be all except
// for the first non-trivial face)
if(e2 != p1)
{
const int flip2 = (EF(e2,0)==f)?0:1;
assert( E(e2,flip2) == d || E(e2,flip2) == s);
E(e2,flip2) = s;
}
F(f,v) = s;
p1 = e1;
break;
}
}
}
}
// Finally, "remove" this edge and its information
kill_edge(e);
return true;
}
bool SSP_collapse_edge(
const decimate_cost_and_placement_func & cost_and_placement,
const decimate_pre_collapse_func & pre_collapse,
const decimate_post_collapse_func & post_collapse,
Eigen::MatrixXd & V,
Eigen::MatrixXi & F,
Eigen::MatrixXi & E,
Eigen::VectorXi & EMAP,
Eigen::MatrixXi & EF,
Eigen::MatrixXi & EI,
min_heap< std::tuple<double,int,int> > & Q,
Eigen::VectorXi & EQ,
Eigen::MatrixXd & C,
int & e,
int & e1,
int & e2,
int & f1,
int & f2,
std::vector<single_collapse_data> & decInfo,
std::vector<std::vector<int>> & decIM)
{
using namespace Eigen;
using namespace igl;
using namespace std;
std::tuple<double,int,int> p;
while(true)
{
// Check if Q is empty
if(Q.empty())
{
// no edges to collapse
return false;
}
// pop from Q
p = Q.top();
if(std::get<0>(p) == std::numeric_limits<double>::infinity())
{
// min cost edge is infinite cost
return false;
}
Q.pop();
e = std::get<1>(p);
// Check if matches timestamp
if(std::get<2>(p) == EQ(e))
{
break;
}
// must be stale or dead.
assert(std::get<2>(p) < EQ(e) || EQ(e) == -1);
// try again.
}
// Why is this computed up here?
// If we just need original face neighbors of edge, could we gather that more
// directly than gathering face neighbors of each vertex?
std::vector<int> /*Nse,*/Nsf,Nsv;
circulation(e, true,F,EMAP,EF,EI,/*Nse,*/Nsv,Nsf);
std::vector<int> /*Nde,*/Ndf,Ndv;
circulation(e, false,F,EMAP,EF,EI,/*Nde,*/Ndv,Ndf);
bool collapsed = true;
single_collapse_data data;
VectorXi FIdx_onering_pre;
if(pre_collapse(V,F,E,EMAP,EF,EI,Q,EQ,C,e))
{
collapsed = SSP_collapse_edge(
e,C.row(e),
Nsv,Nsf,Ndv,Ndf,
V,F,E,EMAP,EF,EI,e1,e2,f1,f2,decInfo,decIM,data,FIdx_onering_pre);
}else
{
collapsed = false;
}
// cout << "start post collapse" << endl;
post_collapse(V,F,E,EMAP,EF,EI,Q,EQ,C,e,e1,e2,f1,f2,collapsed);
if(collapsed)
{
// ===================
// Derek modifications:
// ===================
decInfo.push_back(data);
// contruct index map for fast query
for (int ii = 0; ii < FIdx_onering_pre.size(); ii++)
decIM[FIdx_onering_pre(ii)].push_back(decInfo.size() - 1);
// ===================
// Derek modifications end
// ===================
// Erase the two, other collapsed edges by marking their timestamps as -1
EQ(e1) = -1;
EQ(e2) = -1;
// TODO: visits edges multiple times, ~150% more updates than should
//
// update local neighbors
// loop over original face neighbors
//
// Can't use previous computed Nse and Nde because those refer to EMAP
// before it was changed...
std::vector<int> Nf;
Nf.reserve( Nsf.size() + Ndf.size() ); // preallocate memory
Nf.insert( Nf.end(), Nsf.begin(), Nsf.end() );
Nf.insert( Nf.end(), Ndf.begin(), Ndf.end() );
// https://stackoverflow.com/a/1041939/148668
std::sort( Nf.begin(), Nf.end() );
Nf.erase( std::unique( Nf.begin(), Nf.end() ), Nf.end() );
// Collect all edges that must be updated
std::vector<int> Ne;
Ne.reserve(3*Nf.size());
for(auto & n : Nf)
{
if(F(n,0) != IGL_COLLAPSE_EDGE_NULL ||
F(n,1) != IGL_COLLAPSE_EDGE_NULL ||
F(n,2) != IGL_COLLAPSE_EDGE_NULL)
{
for(int v = 0;v<3;v++)
{
// get edge id
const int ei = EMAP(v*F.rows()+n);
Ne.push_back(ei);
}
}
}
// Only process edge once
std::sort( Ne.begin(), Ne.end() );
Ne.erase( std::unique( Ne.begin(), Ne.end() ), Ne.end() );
for(auto & ei : Ne)
{
// compute cost and potential placement
double cost;
RowVectorXd place;
cost_and_placement(ei,V,F,E,EMAP,EF,EI,cost,place);
// Increment timestamp
EQ(ei)++;
// Replace in queue
Q.emplace(cost,ei,EQ(ei));
C.row(ei) = place;
}
// cout << "end of a collapse" << endl;
}else
{
// cout << "remove from queue" << endl;
// reinsert with infinite weight (the provided cost function must **not**
// have given this un-collapsable edge inf cost already)
// Increment timestamp
EQ(e)++;
// Replace in queue
Q.emplace(std::numeric_limits<double>::infinity(),e,EQ(e));
}
return collapsed;
}