Hi, On Tuesday 28 February 2012, Martin Großer wrote: > I am surprised about my little test program. I would like compare > displaylists with frame buffer objects. Because, I suppose that the > displaylists have to be faster than the vbo, because the displaylists are > precompiled. But in my example I get another result: > > VBO: 225 FPS > DL: 88 FPS > > Is that possible?
Yes, that's possible. Plenty aspects of this: * GPUs just work in terms of vbos. That means when you program a gpu, you will set up some memory regions for different purposes. Including the vertex program inputs. You need a base pointer, some data types, stride etc... Then you set up some more memory for the fragment processors samplers tell the hardware the base pointer, the data types, strides, dimensions and whatnot. Then tell the setup unit that you want to draw some triangles using these arrays. This *is* basically what you do when you do buffer object draws. * DLists are implemented using vbos anyway. Thinking about how a gpu works in its own. Compiling just could mean to setup a set of vbo arrays and fire the draw on this. Dlist only provide a little more overhead in the sense that you can have degenerated display lists like <dliststart>glBegin(); glVertex()<dlistend>. This list could be combined with one just providing more vertices and containing a terminating glEnd. Which shows pretty fast that dlist handling can get pretty complicated in all its corner cases that are spect in old OpenGL standards valid and backward compatible up to today. * Dlists are deprecated. So driver writers assume since some time that the more optimized fast path should be the vbo/drawarray path. Greetings Mathias -- Dr. Mathias Fröhlich, science + computing ag, Software Solutions Hagellocher Weg 71-75, D-72070 Tuebingen, Germany Phone: +49 7071 9457-268, Fax: +49 7071 9457-511 -- Vorstand/Board of Management: Dr. Bernd Finkbeiner, Michael Heinrichs, Dr. Roland Niemeier, Dr. Arno Steitz, Dr. Ingrid Zech Vorsitzender des Aufsichtsrats/ Chairman of the Supervisory Board: Philippe Miltin Sitz/Registered Office: Tuebingen Registergericht/Registration Court: Stuttgart Registernummer/Commercial Register No.: HRB 382196 _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
