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From Geoff Michel, "New delaunay triangulator attached. I hadn't realised that the erase() method was not erase (first, last) but erase (first, one after the last one you want deleted). This made a big difference; however some of the edges of the terrain were not included as edges in the terrain so I increased the size of the supertriangle, which works but reduces accuracy due to the larger range of coordinates in the supertriangle. (A larger supertriangle forces the triangles using supertriangle vertices to be long and thin, making the triangulation fit the convex hull of the terrain.)

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The loss of accuracy should not affect 'normal' users with terrains that are roughly square (say up to 100:1 aspect ratio) and where the Z range is comparable to the X-Y range. Retested with Pauls data, amalric's strange polygon constraint and the standard test constraints.

I also added 2 tests for routines with a NULL argument passed to them (no-one would usually pass a NULL pointer to these routines unless - as I did in testing- you remove some of the constraints but still pass their pointer to the routine). And I removed 3 tests for triangles which are already removed when generating the geometry.

NB Paul - the previous delaunay triangulator fails under VS8 IF it has any constraints as it attempts to use some vertices that have already been deleted when applying the constraints to edges. Under VS6 and less rigorous compilers it works as the deleted vertices are still in the points stl::Vector; however any added vertices would replace one of the supertriangle vertices with non-disastrous but wrong results."

Note, merged with latest name changes in CVS.
This commit is contained in:
Robert Osfield
2007-01-09 11:42:49 +00:00
parent d6d1a46db9
commit 77e300100c
1 changed files with 70 additions and 72 deletions
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142
src/osgUtil/DelaunayTriangulator.cpp
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@@ -641,24 +641,26 @@ void DelaunayConstraint::removeVerticesInside(const DelaunayConstraint *dco)
void DelaunayConstraint::merge(DelaunayConstraint *dco)
{
unsigned int ipr;
osg::Vec3Array* vmerge=dynamic_cast<osg::Vec3Array*>(getVertexArray());
if (!vmerge) vmerge=new osg::Vec3Array;
setVertexArray(vmerge);
for ( ipr=0; ipr<dco->getNumPrimitiveSets(); ipr++)
{
osg::PrimitiveSet* prset=dco->getPrimitiveSet(ipr);
osg::DrawArrays *drarr=dynamic_cast<osg::DrawArrays *> (prset);
if (drarr)
if (dco) { // 16 Dec 2006 just in case you pass in a NULL pointer
osg::Vec3Array* vmerge=dynamic_cast<osg::Vec3Array*>(getVertexArray());
if (!vmerge) vmerge=new osg::Vec3Array;
setVertexArray(vmerge);
for ( ipr=0; ipr<dco->getNumPrimitiveSets(); ipr++)
{
// need to add the offset of vmerge->size to each prset indices.
unsigned int noff=vmerge->size();
unsigned int n1=drarr->getFirst(); // usually 0
unsigned int numv=drarr->getCount(); //
addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP,n1+noff,numv));
osg::PrimitiveSet* prset=dco->getPrimitiveSet(ipr);
osg::DrawArrays *drarr=dynamic_cast<osg::DrawArrays *> (prset);
if (drarr)
{
// need to add the offset of vmerge->size to each prset indices.
unsigned int noff=vmerge->size();
unsigned int n1=drarr->getFirst(); // usually 0
unsigned int numv=drarr->getCount(); //
addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINE_LOOP,n1+noff,numv));
}
}
osg::Vec3Array* varr=dynamic_cast<osg::Vec3Array*>(dco->getVertexArray());
if (varr) vmerge->insert(vmerge->end(),varr->begin(),varr->end());
}
osg::Vec3Array* varr=dynamic_cast<osg::Vec3Array*>(dco->getVertexArray());
if (varr) vmerge->insert(vmerge->end(),varr->begin(),varr->end());
}
void DelaunayTriangulator::_uniqueifyPoints()
@@ -771,9 +773,12 @@ bool DelaunayTriangulator::triangulate()
// gwm added 1.05* to ensure that supervertices are outside the domain of points.
// original value could make 2 coincident points for regular arrays of x,y,h data.
// this mod allows regular spaced arrays to be used.
points_->push_back(osg::Vec3(minx - 1.05*(maxx - minx), miny - 0.01*(maxy - miny), 0));
points_->push_back(osg::Vec3(maxx + 0.01*(maxx - minx), miny - 0.01*(maxy - miny), 0));
points_->push_back(osg::Vec3(maxx + 0.01*(maxx - minx), maxy + 1.05*(maxy - miny), 0));
// 16 Dec 2006 this increase in size encourages the supervertex triangles to be long and thin
// thus ensuring that the convex hull of the terrain points are edges in the delaunay triangulation
// the values do however result in a small loss of numerical resolution.
points_->push_back(osg::Vec3(minx - 2.0*(maxx - minx), miny - 1.0*(maxy - miny), 0));
points_->push_back(osg::Vec3(maxx + 1.0*(maxx - minx), miny - 1.0*(maxy - miny), 0));
points_->push_back(osg::Vec3(maxx + 1.0*(maxx - minx), maxy + 2.0*(maxy - miny), 0));
// add supertriangle to triangle list
triangles.push_back(Triangle(last_valid_index+1, last_valid_index+2, last_valid_index+3, points));
@@ -1036,7 +1041,7 @@ bool DelaunayTriangulator::triangulate()
}
// remove 3 supertriangle vertices from points. They may not be the last vertices in points if
// extra points have been inserted by the constraint re-triangulation.
points->erase(points->begin()+last_valid_index+1,points->begin()+last_valid_index+3);
points->erase(points->begin()+last_valid_index+1,points->begin()+last_valid_index+4);
//last_valid_index = points->size()-1; // the last valid vertex is last point.
// end of dec 2006 changes.
@@ -1051,9 +1056,10 @@ bool DelaunayTriangulator::triangulate()
{
// don't add this triangle to the primitive if it shares any vertex with
// the supertriangle
// Also don't add degenerate (zero radius) triangles
if (ti->a() <= last_valid_index && ti->b() <= last_valid_index && ti->c() <= last_valid_index && ti->get_circumcircle().z()>0.0)
// the supertriangle triangles have already been removed.
// Don't need this test: ti->a() <= last_valid_index && ti->b() <= last_valid_index && ti->c() <= last_valid_index &&
// Don't add degenerate (zero radius) triangles
if ( ti->get_circumcircle().z()>0.0)
{
if (normals_.valid())
@@ -1076,57 +1082,49 @@ bool DelaunayTriangulator::triangulate()
void DelaunayTriangulator::removeInternalTriangles(DelaunayConstraint *dc )
{
// Triangle_list *triangles
// remove triangle from terrain prim_tris_ internal to each constraintline
// and move to the constraint line to make an alternative geometry,
// possibly with alternative texture, and texture map
int ndel=0;
osg::Vec3Array::iterator normitr;
if( normals_.valid() )
normitr = normals_->begin();
// osg::notify(osg::WARN) << "DelaunayTriangulator: removeinternals, " << std::endl;
for (osg::DrawElementsUInt::iterator triit=prim_tris_->begin(); triit!=prim_tris_->end(); )
{
// triangle joins points_[itr, itr+1, itr+2]
Triangle tritest((*triit), *(triit+1), *(triit+2), points_.get());
/* if ((*triit==166 && *(triit+1)==162 && *(triit+2)==161) ||
(*triit==166 && *(triit+1)==165 && *(triit+2)==164) )
{
osg::Vec3 ctr=tritest.compute_centroid( points_.get());
osg::notify(osg::WARN) << "testverts: " << ((*points_)[(*triit)].x()) << "," << ((*points_)[*(triit)].y()) <<","<<((*points_)[*(triit)].z())<<std::endl;
osg::notify(osg::WARN) << "testverts: " << ((*points_)[*(triit+1)].x()) << "," << ((*points_)[*(triit+1)].y()) <<","<<((*points_)[*(triit+1)].z())<<std::endl;
osg::notify(osg::WARN) << "testverts: " << ((*points_)[*(triit+2)].x()) << "," << ((*points_)[*(triit+2)].y()) <<","<<((*points_)[*(triit+2)].z())<<std::endl;
osg::notify(osg::WARN) << "DelaunayTriangulator: why remove, " << (*triit) << "," << *(triit+1) <<","<<*(triit+2)<<
" " << (dc->windingNumber(ctr))<< std::endl;
}*/
if ( dc->contains(tritest.compute_centroid( points_.get()) ) )
{
// centroid is inside the triangle, so IF inside linear, remove
// osg::notify(osg::WARN) << "DelaunayTriangulator: remove, " << (*triit) << "," << *(triit+1) <<","<<*(triit+2)<< std::endl;
dc->addtriangle((*triit), *(triit+1), *(triit+2));
triit=prim_tris_->erase(triit);
triit=prim_tris_->erase(triit);
triit=prim_tris_->erase(triit);
if (normals_.valid())
{
// erase the corresponding normal
normitr=normals_->erase(normitr);
}
ndel++;
}
else
{
if (normals_.valid())
{
normitr++;
}
triit+=3;
}
}
if (dc) { // 16.12.06 just in case....
// Triangle_list *triangles
// remove triangle from terrain prim_tris_ internal to each constraintline
// and move to the constraint line to make an alternative geometry,
// possibly with alternative texture, and texture map
int ndel=0;
osg::Vec3Array::iterator normitr;
if( normals_.valid() )
normitr = normals_->begin();
osg::notify(osg::INFO) << "end of test dc, deleted " << ndel << std::endl;
// osg::notify(osg::WARN) << "DelaunayTriangulator: removeinternals, " << std::endl;
for (osg::DrawElementsUInt::iterator triit=prim_tris_->begin(); triit!=prim_tris_->end(); )
{
// triangle joins points_[itr, itr+1, itr+2]
Triangle tritest((*triit), *(triit+1), *(triit+2), points_.get());
if ( dc->contains(tritest.compute_centroid( points_.get()) ) )
{
// centroid is inside the triangle, so IF inside linear, remove
// osg::notify(osg::WARN) << "DelaunayTriangulator: remove, " << (*triit) << "," << *(triit+1) <<","<<*(triit+2)<< std::endl;
dc->addtriangle((*triit), *(triit+1), *(triit+2));
triit=prim_tris_->erase(triit);
triit=prim_tris_->erase(triit);
triit=prim_tris_->erase(triit);
if (normals_.valid())
{
// erase the corresponding normal
normitr=normals_->erase(normitr);
}
ndel++;
}
else
{
if (normals_.valid())
{
normitr++;
}
triit+=3;
}
}
osg::notify(osg::INFO) << "end of test dc, deleted " << ndel << std::endl;
}
}
//=== DelaunayConstraint functions