Hi Olivier,
It sounds like the next thing to investigate would be the size of the
bounding sphere that it's testing against, perhaps there is an error in the
bounding sphere settings that is resulting in the traversal being culled
prematurely.
Robert.
On 22 November 2013 14:03, Olivier Tournaire <olit...@gmail.com> wrote:
> Hi Robert,
>
> Thank you for your answer. Unfortunately, I cannot share the model ...
> However, I can share the code.
>
> Here it is:
>
> // Building a osgUtil::PolytopeIntersector from a CONCAVE planar polygon
>
> /* 1) split the concave polygon in its convex rings */
> /* 2) iterate over each convex ring to build a convex osg::Polyope
> */
>
> // Begin loop over convex rings
> osg::Polytope currentBuildingPolytope;
> for(int j=0;j<ring.getNumPoints()-1;++j)
> {
> osg::Vec3d A( ring.getX(j), ring.getY(j), ring.getZ(j) );
> osg::Vec3d B( ring.getX(j+1), ring.getY(j+1), ring.getZ(j+1) );
> osg::Vec3d C( ring.getX(j+1), ring.getY(j+1), ring.getZ(j+1)+delta
> ); // delta > 0.
>
> osg::Vec3d AB = B-A; AB.normalize();
> osg::Vec3d BC = C-B; BC.normalize();
> osg::Vec3d n = BC^AB; n.normalize();
>
> osg::Plane p(n,A);
> currentBuildingPolytope.add(p);
> }
> osg::ref_ptr<osgUtil::PolytopeIntersector>
> currentPolytopeIntersector = new
> osgUtil::PolytopeIntersector(currentBuildingPolytope);
>
> currentPolytopeIntersector->setDimensionMask(osgUtil::PolytopeIntersector::DimTwo);
> // End loop over convex rings
>
> /* 3) add the convex osg::Polytope to a vector<
> ref_ptr<osgUtil::PolytopeIntersector> > */
> _polytopeIntersectors.push_back(currentPolytopeIntersector);
>
> /* 4) Find intersections of the model with the previously build
> osgUtil::PolytopeIntersectors */
> bool hasIntersections = false;
> for(unsigned int i=0;i<_polytopeIntersectors.size();++i)
> {
> osgUtil::IntersectionVisitor
> visitor(_polytopeIntersectors[i].get());
> osg::ref_ptr<osgSim::DatabaseCacheReadCallback> _readCallback
> = new osgSim::DatabaseCacheReadCallback;
> visitor.setReadCallback(_readCallback);
> model->accept(visitor); // model contains one triangle per
> Drawable
>
> if(_polytopeIntersectors[i]->containsIntersections())
> {
> hasIntersections = true;
> _numIntersections +=
> _polytopeIntersectors[i]->getIntersections().size();
> // ...
> }
> // ...
> }
>
> If you see anything wrong, please let me know.
>
> As I tols in my first post, the reader callback works quite well (my DB
> model contains around 150 files). Debugging my application, the method
> IntersectionVisitor::apply(osg::PagedLOD& plod) exits on the first line
> only if _intersectorStack.back()->enter(node); returns false. This happen
> in LineSegmentIntersector::intersects(const osg::BoundingSphere& bs),
> because of this line:
> if (d<0.0) return false;
> which seems to mean that the bounding sphere of the current PagedLOD is
> not intersected by the line.
>
> Hope this give you more :)
>
> Regards,
>
> Olivier
>
>
> 2013/11/21 Robert Osfield <robert.osfi...@gmail.com>
>
>> Hi Oliver,
>>
>> I have looked at the OSG code and can't see a specific cause, but then I
>> don't have your code or models so it's all just guessing.
>>
>> Does LineOfSight work fine for you? If so I'd recommend stepping through
>> to see what happening and then compare it with your own usage.
>>
>> Robert.
>>
>>
>> On 19 November 2013 19:58, Olivier Tournaire <olit...@gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> Sorry for the noise, but, as I did not receive any answer, I am
>>> interested if someone has an idea on the topic.
>>>
>>> Regards,
>>>
>>> Olivier
>>>
>>>
>>> 2013/11/15 Olivier Tournaire <olit...@gmail.com>
>>>
>>>> Hi,
>>>>
>>>> I am currently trying to retrieve some specific triangles in a PagedLOD
>>>> model. To do so, I use a PolytopeIntersector with an IntersectionVisitor.
>>>> As my model is a PagedLOD, I have set up a reader callback, directly taken
>>>> from osgSim::LineOfSight.
>>>>
>>>> The intersector works, but not as expected: it gives me the triangles
>>>> at the lowest resolution, whereas I would expect to have them at the finest
>>>> LOD. Debugging my program showed me that the void
>>>> IntersectionVisitor::apply(osg::PagedLOD& plod) method goes where it has to
>>>> (i.e., it traverses correctly all childs until the best resolution).
>>>>
>>>> As the IntersectionVisitor sets up by default to use
>>>> the USE_HIGHEST_LEVEL_OF_DETAIL flag, I am wondering if I am missing
>>>> something and if you could give some pointers on how to achieve triangles
>>>> extraction at the finest LOD.
>>>>
>>>> The "header" root file is:
>>>>
>>>> osg::PagedLOD {
>>>> UniqueID 1
>>>> Name "Tile_+001_+006.osgb"
>>>> CenterMode USER_DEFINED_CENTER
>>>> UserCenter -741.555 904.039 94.1168 213.403
>>>> RangeMode PIXEL_SIZE_ON_SCREEN
>>>> RangeList 2 {
>>>> 0 106.702
>>>> 106.702 1e+030
>>>> }
>>>> DatabasePath FALSE
>>>> RangeDataList 2 {
>>>> ""
>>>> "Tile_+001_+006_L15_0.osgb"
>>>> }
>>>> PriorityList 2 {
>>>> 0 1
>>>> 0 1
>>>> }
>>>>
>>>> The "header" of the child file (Tile_+001_+006_L15_0.osgb) is:
>>>>
>>>> osg::PagedLOD {
>>>> UniqueID 1
>>>> Name "Tile_+001_+006_L15_0.osgb"
>>>> CenterMode USER_DEFINED_CENTER
>>>> UserCenter -741.869 906.466 94.7166 206.312
>>>> RangeMode PIXEL_SIZE_ON_SCREEN
>>>> RangeList 2 {
>>>> 0 206.312
>>>> 206.312 1e+030
>>>> }
>>>> DatabasePath FALSE
>>>> RangeDataList 2 {
>>>> ""
>>>> "Tile_+001_+006_L16_00.osgb"
>>>> }
>>>> PriorityList 2 {
>>>> 0 1
>>>> 0 1
>>>> }
>>>>
>>>>
>>>> Hope you could help
>>>>
>>>> Regards,
>>>>
>>>> Olivier
>>>>
>>>
>>>
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