XreaL

Now I want to show you the need of Vertex Buffer Object based rendering. Usually most open source quake based game engines have a similar renderer design to id Tech 3 nowadays. They usually use vertex arrays (VA) or compiled vertex arrays (CVA) that they create every frame by processing the entire scene geometry. You usually find this practice in IOQuake3 (of course), all IOQuake3 based games like Urban Terror or Tremulous, Q2E, QFusion, Overdose (at least an old version) and Alien Arena. This is a design that worked well in 1999 but it is a quite bad practice in 2009.

XreaL follows the advices of GDC papers and uses VBO based rendering for almost everything to avoid this horrible CPU bottleneck. The model geometry is uploaded like textures and don’t have to move over the PCIe bridge every frame.

There is a nice heavy benchmark map called tvy-bench.pk3 for Quake3 by hipshot that could be found at http://www.zfight.com. It is really nice and contains a test scene with really many polygons.

To make it short. Traditional renderers don’t give you more than 30 fps no matter what high-end GFX card you have. The XreaL renderer gives you more than stable 125 fps.

IOQuake3 with 22 fps in 1280×768:

XreaL renders it with 148 fps:

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