I don't think here is an existing optimizer that builds draw element lists from arrays of vertices like you describe. I've written one and will submit it in the next 24 hours.
Tim On Tue, Feb 23, 2010 at 4:12 PM, Lars Richter <[email protected]>wrote: > Hi, > > I'm new to OSG. I'm working on a problem where I use OSG and osgNV. I'm > reading Geometry from .osg files which I exported from 3ds MAX using OSGExp. > > There are different methods to add a shape via osgNV. For simple shapes > like spheres, boxes etc. everything is nice and simple. But to add an > arbitrary shape, I have to build a NxTriangleMesh first, using the Cooking > interface of PhysX. > The PhysX documentation states: > > Do not duplicate identical vertices. If two triangles are sharing a > vertex, this vertex should only occur once in the vertex list, and both > triangles should index it in the index list. If you create two copies of the > vertex, the collision detection code won't know that it is actually the same > vertex, which leads to decreased performance and unreliable results. > > > So my problem is, that I need to convert the highly redundant vertex list > from an .osg file to an array where every vertex is unique and to build up a > triangle array where the entries refer to the corresponding indices in the > vertex array. > > To clarify, a simple example: A tetrahedron has 4 triangles and 4 vertices. > But an .osg file of a tetrahedron would most likely look similar to this: > > Geode { > > UniqueID Geode_0 > > DataVariance DYNAMIC > > nodeMask 0xffffffff > > cullingActive TRUE > > num_drawables 1 > > Geometry { > > DataVariance DYNAMIC > > useDisplayList TRUE > > useVertexBufferObjects FALSE > > PrimitiveSets 1 > > { > > DrawArrays TRIANGLES 0 12 > > } > > VertexArray Vec3Array 12 > > { > > 1 -1 -1 > > -1 -1 1 > > -1 1 -1 > > -1 -1 1 > > 1 1 1 > > -1 1 -1 > > -1 1 -1 > > 1 1 1 > > 1 -1 -1 > > 1 1 1 > > -1 -1 1 > > 1 -1 -1 > > } > > NormalBinding PER_VERTEX > > NormalArray Vec3Array 12 > > { > > -0.57735 -0.57735 -0.57735 > > -0.57735 -0.57735 -0.57735 > > -0.57735 -0.57735 -0.57735 > > -0.57735 0.57735 0.57735 > > -0.57735 0.57735 0.57735 > > -0.57735 0.57735 0.57735 > > 0.57735 0.57735 -0.57735 > > 0.57735 0.57735 -0.57735 > > 0.57735 0.57735 -0.57735 > > 0.57735 -0.57735 0.57735 > > 0.57735 -0.57735 0.57735 > > 0.57735 -0.57735 0.57735 > > } > > ColorBinding OVERALL > > ColorArray Vec4Array 1 > > { > > 1 1 1 1 > > } > > } > > } > > > > It can be clearly seen that there are 12 verticies. 3 for each triangle. > And in fact there are only 4 different verticies as there should be. But > they are listed several times, according to how many triangles they are part > of. > > Is there a way to convert this redundant list to a list where every vertex > is unique and to build up the triangle list as well, which only holds the > indices of the vertex list? > Or did anyone come across a similar problem and did already write code that > does this? > > Thank you! > > Cheers, > Lars > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=24706#24706 > > > > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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