Your problem seems to stem from having to repeat vertices multiple times so that each can have its own vertex. For example, let's say you need to repeat each vertex 4 times because it is shared by 4 different facets. This means you have xyz vert/norm (24 bytes) * 4 * 20M = ~2GB. Do I understand the issue correctly?
You don't want to specify the normal once per facet because that will send you down the OpenGL slow path (setting normal binding to BIND_PER_PRIMITIVE). But this would be the easiest change and fastest course of action, and with display lists on, this could still produce acceptable performance. There are normal compression schemes. I patented one while at HP that is lossy but allows you to specify a variable amount of compression. In our work, we found that a 6:1 compression ration (store the normal as a 2-byte short) still produced pretty good visual results. If you search for my name in any patent search engine you can find more info. This algorithm was storage-efficient but not computationally efficient. For a computationally efficient algorithm, try representing the xyz components as 10 bit signed ints stored in a single word and then unpack them in a shader. Special data types allow other types of normal compression. For example, bump maps, or normals for heightfield data, only need two components. The third can always be derived. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com +1 303 859 9466 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
