From Valve Developer Community
This is a description of what each version of DirectX is capable of, for reference when creating fallback materials. Under each heading are features not available in previous versions of DirectX.
To test lower-quality DirectX levels on a more advanced graphics card, use the mat_dxlevel CVAR. Set it to 60, 70, 80, 81, 90, 95 or 98 to set the corresponding DirectX version; it is not possible to run at a higher level than the graphics hardware is capable of.
DirectX 6-class graphics cards include the Nvidia TNT2 and Matrox G400.
DirectX 7-class graphics cards include the Nvidia GeForce 256, 2, 2MX and 4MX cards and the ATI Radeon 7xxx series.
- Blob shadows
- Displacement map texture blending
DirectX 8-class graphics cards include the Nvidia GeForce4 Ti and most of the GeForce FX 5x00 series (while technically DirectX 9 cards, the latter suffer from major performance problems with the DX9 rendering path).
- Refractions with the use of a du/dv map
- Dynamic shadows
- Directional lighting on world brushes using normal maps
- Cube-mapped specular effects
- Cube-mapped water
- Low-quality reflective water (used sparingly)
DirectX 8.1-class graphics cards include the Nvidia GeForce FX 5800 and 5900 and the ATI RADEON 8500/9100 and 9000/9200 cards.
- Soft edge dynamic shadows
DirectX 9 (Shader Model 2)
DirectX 9-class graphics cards include the Nvidia GeForce 6600 and 6800 series and the ATI RADEON 9500/9600, 9700/9800, X300/X600 and X800 cards.
- Refractions with the use of a bump-map
- High-quality reflective water (used frequently)
- Softer edge dynamic shadows
- Normal-mapped lighting on models
- Improved-quality specular effects
- High dynamic range rendering
- Phong shading
DX9 Shader Model 3
Referred to as "DirectX 9.0+" and "dxlevel 95".
- Lightwarp support
- To do: More
Referred to as "dxlevel 98".
- GPU Particle Physics
- To do: More
These screenshots demonstrate displacement map texture blending, directional lightmaps and cubemapped then reflective water.
These screenshots show shadow quality at different rendering levels, ranging from none to soft, dynamic shadows.
These screenshots show directional lightmaps and cube-mapped specular effects.
These screenshots demonstrate the use of normal-mapping on models. The final shot has full, normal-mapped lighting.
- 3D Performance with Half-Life 2 - a comparison of different graphics hardware when running Half-Life 2.