Hi Fred, You interpretation of what Geometry::setUseVertexBufferObjects(true) is correct, so what you are see looks to be a bug. Which version of the OSG are your using?
A couple of weeks ago I was looking into VBO setup issues relating to the new serializers and tracked down the issues I was seeing to src/osg/Geometry.cpp, so I then tidied up the loopholes in the set up of the VBO's. The problems I saw was that is some usage models the VBO's were all setup correctly, but others it wasn't, so I closed these loopholes, these fixes are now checked into svn/trunk. There might still be some combinations of usage that I didn't spot, if svn/trunk has them then just point me in the right direction. Robert. On Tue, Nov 23, 2010 at 3:41 PM, Fred Smith <[email protected]> wrote: > Hi, > > The way I should be using Element Buffer Objects is unclear to me. > If I use the following code: > > > Code: > osg::Geometry* polyGeom = new osg::Geometry(); > polyGeom->setUseVertexBufferObjects(true); > > osg::ref_ptr<osg::DrawElementsUShort> de = new > osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLE_STRIP,numIndices,myIndices); > polyGeom->addPrimitiveSet(de); > > > > I expect the geometry to be using a VBO for vertex data *and* a VBO for index > data. However it seems only a VBO for vertex data is used, eg. the following > GL code is executed: > > glBindBuffer(GL_ARRAY_BUFFER, &bufferid); > glBufferData(GL_ARRAY_BUFFER, ...); > > glVertexPointer(3, GL_FLOAT, 0, offset_to_VBO); > glDrawElements(GL_TRIANGLE_STRIP, 4, ..., pointer_to_local_index_array); > > No EBO is created then used in the last parameter in glDrawElements(). > > I am surprised this block of code above doesn't work as expected, as the > Geometry.cpp file looks like this: > > > Code: > bool Geometry::addPrimitiveSet(PrimitiveSet* primitiveset) > { > if (primitiveset) > { > if (_useVertexBufferObjects) > addElementBufferObjectIfRequired(primitiveset); > [ ... ] > > > > > I also tried: > > de->setElementBufferObject(new osg::ElementBufferObject()); > > but still no luck. > > Furthermore, I checked the osgparametric sample and something else is > disturbing me. > > In this sample, when useVBO = true, createModel() calls > geom->setUseVertexBufferObjects(true), but still manually sets up: > > 1) a VertexBufferObject, that it binds to the vertices > 2) an ElementBufferObject, that it binds to the primitiveset > > Isn't the call to geom->setUseVertexBufferObjects(true) sufficient? Isn't > that the whole purpose of setUseVertexBufferObjects()? > > I'm kind of confused here. Could somebody shed some light on this. > > Thanks, > -F > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=33987#33987 > > > > > > _______________________________________________ > 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
