Game Engine: DirectX 7, DirectX 8, DirectX 9
Five generations of graphics hardware have passed by since Valve started its Half-Life 2 project, and the DirectX API from Microsoft has grown three versions up in the meanwhile. As a result, the graphics engine of the game has been evolving along with the technology. Here is how Valve describes the capabilities of their Source engine in its current implementation depending on the DirectX version.
- Screen space effects are really simple;
- No model decals;
- No detail props;
- No refractive water;
- Reduced decal visibility distance;
- No bumpmaps;
- Reduced model LODs;
- Reduced material mip level.
- On some graphics cards with a poor fill rate, bumpmaps may become disabled in some scenes that use a lot of bumpmaps. At the moment, this is true for the GeForce Ti4200, but Valve says it has collaborated with NVIDIA on a solution to reactivate bumpmaps on the GeForce Titanium 4200;
- Water by default is refractive but does not have local reflections;
- Water has a hard edge when it meets waterside volumetric fog, its per-vertex screen space effects are better than DirectX 7.0, but still simple, Valve says;
- Shadows are render-to-texture but are not super-sampled to make them look softer.
- Water by default is refractive, but does not have local reflections. If you activate local reflections on a DirectX 8.1 graphics card, it will occur in one pass as opposed to taking two passes on DirectX 8.0 hardware, which will make it cheaper from the fill rate perspective;
- As in the DirectX 8.0 rendering path, water has a hard edge when it meets waterside volumetric fog; its per-vertex screen space effects are better than that of the DirectX 7.0, but still simple;
- Shadows are render-to-texture and are super-sampled to make them look softer.
- Water by default is refractive with local reflections from the world geometry;
- Water refraction realistically refracts the geometry beneath the water (when looking into the water) based on the depth of the geometry in DirectX 9.0;
- There is a special water-rendering feature which smoothes out the shorelines and reduces water refraction in areas with shallow water;
- There is a gradual blend from water to waterside volumetric fog; its per-pixel screen space effects (post effects) are more complex;
- Shadows are render-to-texture and are super-sampled to make them look softer;
- Certain displacements use blended bumpmaps instead of single bumpmaps (for example, displacements that blend between sand and rocks).
As you see, the most eye-pleasing and demanding rendering path of the Source engine is the DirectX 9.0 one that is intended for the latest generations of high-end graphics cards from ATI Technologies and NVIDIA Corp.