Hi Robert! The question was how can I draw my geometry using elements from start index to end index. And as far as I understand I have to delete whole ebo, and then create new ebo with new bounds. I simply want to do it more efficiently without remapping buffers. Roman.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Robert Osfield Sent: Monday, June 14, 2010 12:06 PM To: [email protected] Subject: Re: [osg-users] Draw dynamic line with LODs and EBO Hi Roman, 100,000 points is nothing for a modern graphics card, they can happily handle 10 times that are 60Hz. Given this I would say just create you geometry efficiently and your done, no need to complicate things further. Robert. On Fri, Jun 11, 2010 at 3:27 PM, Roman Grigoriev <[email protected]> wrote: > Hi, > I have to make in my app dynamic lines. As far as I know display lists are deprecated for now on GLES2 platform I try to make it using VBO+EBO, like in osgparametric,so now it works fine. But I have to draw up to 1000 lines with 100 points so it can be so hard to GPU. So I decided to recalculate EBO using LOD strategy. So I'll calculate distance to my point and remove odd indices. Could you please give me some snippet how to work with EBO in update or draw callback? > Also my lines are trajectories and I have to draw them respectively to simulation time. But I found that I can't change size of element buffer. > Because I found in PrimitiveSet.cpp > this lines > > Code: > > void DrawElementsUInt::draw(State& state, bool useVertexBufferObjects) const > { > ....... > if (ebo) > { > if (_numInstances>=1) state.glDrawElementsInstanced(mode, size(), GL_UNSIGNED_INT, (const GLvoid *)(ebo->getOffset(getBufferIndex())), _numInstances); > else glDrawElements(mode, size(), GL_UNSIGNED_INT, (const GLvoid *)(ebo->getOffset(getBufferIndex()))); > } > } > > > > so here size() - total size of element buffer and I create for example EBO with 200 indices total and want draw only first 100 indices - how can I make it? > > for the reference here is my code > > Code: > > osg::Node* createModel( bool dynamic, bool useVBO) > { > osg::Geode* geode = new osg::Geode; > osg::Geometry* geom = new osg::Geometry; > geode->addDrawable(geom); > osg::Vec3 row(0.0f,0.0f,0.0); > unsigned int num_x = 200; > unsigned int num_y = 20; > unsigned int vert_no = 0; > osg::Vec3Array* vertices = new osg::Vec3Array( num_x ); > > unsigned int iy; > for(iy=0; iy<num_x; iy++) > { > (*vertices)[vert_no++] = row; > row.y()=1000.0f*iy; > row.z()+=100; > } > geom->setVertexArray(vertices); > osg::VertexBufferObject* vbo = useVBO ? new osg::VertexBufferObject : 0; > if (vbo) vertices->setVertexBufferObject(vbo); > osg::ElementBufferObject* ebo = useVBO ? new osg::ElementBufferObject : 0; > osg::DrawElementsUInt* elements = new osg::DrawElementsUInt(GL_LINE_STRIP_ADJACENCY_EXT, num_x); > unsigned int element_no = 0; > for(unsigned int ix = 0; ix<num_x; ix++) > { > (*elements)[element_no++] = ix; > } > > geom->addPrimitiveSet(elements); > geom ->setDataVariance(osg::Object::DYNAMIC); > geom->setDrawCallback(new DrawCallback()); > if (ebo) elements->setElementBufferObject(ebo); > geom->setUseVertexBufferObjects(useVBO); > return geode; > } > > > > ... > > Thank you! > > Cheers, > Roman[/code] > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=28826#28826 > > > > > > _______________________________________________ > 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 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
