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Performance Leap: NVIDIA GeForce 6800 Ultra

Vertex Engine

The vertex shader units also conform to Microsoft's DirectX 9.0c specification, meaning Vertex Shader 3.0.

Vertex Shader Summary
Shader Model2.02.0a3.0
#of instruction slots256256>= 512
Max # of instructions executed655356553565535
Instruction Predication-YesYes
Temp Registers121332
#constant registers>= 256>= 256>= 256
Static Flow ControlYesYesYes
Dynamic Flow Control-YesYes
Dynamic Flow Control depth-2424
Vertex Texture Fetch--Yes
#of texture samplers--4
Geometry Instancing Support--Yes

The vertex engine has seen a great range of improvements and extensions compared to the NV35 / 38. NV40 possesses 6 vertex units which follow a MIMD (multiple input, multiple data) design. NVIDIA also sets a new record with a triangle transform rate of 600 million polys/second (Radeon 9800XT = 412, FX 5950 = 356).

Vertex shader programs can theoretically be of infinite length in VS 3.0. Thanks to the extension of the dynamic flow control (more looping / branching options and new subroutine functions), shader code can now be written much more efficiently and offers new options for effects.

Again, here's summary of features:

  • Full Support for Shader Model 3.0
  • 216 (65,535) length vertex programs
  • Vertex processing w/texture - displacement mapping
  • Dynamic flow control - Branching, Call & Return, Subroutines
  • Geometry Instancing (vertex stream divider)