Hi Bob, The OSG's DrawElements* encapsulate OpenGL's glDrawElements call, so it might be best if you just looked up OpenGL documentation online in books to see how the indices in the DrawElementsUByte/UShort map to triangles.
Another alternative to looking at the low level primitives is to use a functor like the TriangleIndexFunctor or TriangleFunctor. Have a search through the OSG code base to see places where this used. Robert. On 5 June 2012 10:50, Bob Slobodan <[email protected]> wrote: > Hi, > > >> >> You original asked for vertices... now you want triangles... is that >> because you now know how to get the vertices, or is it that you now >> know what you want more precisely?? > > > I knew how to get the vertex array, but the problem is that I don't know how > to get the vertices for each sub-polygon (triangles) generated by the > tessellation. > > >> Is that you are asking how to get the primitive data from a >> PrimitiveSet > > > Basically yes. My problem is that I don't really get how the tesselation > works and how to create new polygons using the geometry modified by the > tessellation. I thought that the tesselation would simply add new > PrimitiveSet such as DrawArrays and that I could have created my new polygons > using the getFirst() and getCount() function of DrawArrays with my > vertexArray. Unfortunately, when I look at my geometry after the tesselation, > it only has DrawElementsUByte, and I don't see how I could get a list of > triangles from this PrimitiveSet. I've looked at the DOC, the headers and the > source but I don't see what to do. > > >> Might I also ask you for what purpose you want to know the >> vertices/primitive data? What are you trying to do with it? > > > For my project, I had to create a class that handles Surfaces (it displays > anykind of polygon and it has some useful tools). And I have to implement a > tool that "triangulate" the polygon and create new Surfaces with each > triangle ; so instead of trying to implement my own tessellation algo, I > thought I would simply use the osg tessellation. > > I'm really sorry for my lack of precision in my previous posts. And thank you > a lot for taking the time to help me. > > Cheers, > Bob > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=48043#48043 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
