Qfusion is a game engine based on sources from Quake II code. It is available for download and modification for free under the GNU General Public License (GPL). Qfusion has helped to set the bar for many other Quake II engine projects. A popular feature of the engine is that it is said to be able to correctly render the entire range of content for Quake III.
More recent versions of Qfusion engine also extend the Q3 rendering scheme to include per pixel shading support, soft shadows, other newer generation features.
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