TruForm was an early tessellation implementation created by ATI and employed primarily on Radeon 8500 (R200). It was never accepted into the DirectX or OpenGL specifications.
Before the adoption of pixel shader-enhanced bump mapping methods such as normal and parallax mapping that simulate higher mesh detail, curved 3D shapes in games were typically created with large numbers of triangles. TruForm creates a curved surface using the existing triangles, and tessellates this surface to make a new, more detailed polygonal model. By performing this geometry improvement on the graphics card, bus transfer and system memory utilization are reduced compared to if a complex mesh was used for the entire process. For best results, Truform needs to be implemented in the models with flags that identify areas to be tessellated.
The Radeon R200 chip is the only chip that performs TruForm fully in hardware. Radeon 9000 and later use a combination of CPU and vertex shader processing to perform it and this impacts performance and stability. (Radeon 9100 also uses an R200 chip so it will support TruForm just like Radeon 8500.) In later versions of Catalyst drivers, the TruForm feature is removed. Beginning with the Radeon R520 generation, TruForm was no longer advertised as a hardware feature.
Games with support
- Command & Conquer: Renegade
- Counter-Strike (ati_subdiv "2.0", ati_npatch "1.0")
- The Elder Scrolls III: Morrowind (unofficially, with the FPS Optimizer)
- FTE QuakeWorld (Quake World, Net Quake, Quake II, Quake, Quake III: Arena, Hexen 2, Nexuiz)  
- Hexen II (TruHexen2 Patch, developed by RaVeN )
- Madden NFL 2004
- Neverwinter Nights (must edit the game's ".ini" file and set "Enable Truform=1")
- Quake (TruQuake Patch)
- Quake 2 (TruQuake2 Patch)
- Quake III Arena  (developed by RaVeN )
- Return to Castle Wolfenstein
- Serious Sam
- Soldier of Fortune
- Soldier of Fortune II: Double Helix
- Tom Clancy's Rainbow Six
- Unreal Tournament (TruUT Patch)
- Unreal Tournament 2003 and Unreal Tournament 2004 (must edit the game's ".ini" file and set "UseNPatches=True")
- Wolfenstein: Enemy Territory