TruForm

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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.

Overview

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[1]. 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[2] 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

External links

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