The Cg Runtime Cyril Zeller Cg Pipeline Graphics

The Cg Runtime Cyril Zeller

Cg Pipeline Graphics programs are written in Cg. . . and compiled to. . . low-level assembly code. . . that runs on any GPU compatible with Direct. X or Open. GL Cg Runtime API

Compiling Offline At Development Time Cg program source code Cg Compiler Shader program assembly code Shader Compiler (nvasm. exe, psa. exe) Shader program binary code // // Diffuse lighting // float d = dot(normalize(frag. N), normalize(frag. L)); if (d < 0) d = 0; c = d*tex 2 D(t, frag. uv)*diffuse; … … DP 3 RSQ MUL DP 3 MAX MUL TEX MUL … r 0. x, f[TEX 0]; r 0. x, r 0. x; r 0, r 0. x, f[TEX 0]; r 1. x, f[TEX 1]; r 1. x, r 1. x; r 1, r 1. x, f[TEX 1]; r 0, r 1; r 0. x, 1. 0; r 0, r 0. x, DIFFUSE; r 1, f[TEX 1], 0, 2 D; r 0, r 1; At Runtime At initialization: Load assembly or binary program For every frame: Load program parameters to hardware registers Set rendering state Load geometry Render

Compiling at Runtime At Development Time At Runtime At initialization: Compile and load Cg program source code // // Diffuse lighting // float d = dot(normalize(frag. N), normalize(frag. L)); if (d < 0) d = 0; c = d*tex 2 D(t, frag. uv)*diffuse; … For every frame: Load program parameters with the Cg Runtime API Set rendering state Load geometry Render

Pros and Cons of Runtime Compilation Pros: Future compatibility: The application does not need to change to benefit from future compilers (future optimizations, future hardware) Easy parameter management Cons: Loading takes more time because of compilation Cannot tweak the result of the compilation

Cg Runtime Architecture Core Cg Runtime: cg. Create. Program Direct 3 D Cg Runtime: cg. D 3 D 9 Load. Program Open. GL Cg Runtime: cg. GLLoad. Program

Core Cg Runtime Does not make any 3 D API call Allows you to: Create a context: cg. Create. Context() Compile a program for a given profile (vs_2_0, vs_2_x, ps_2_0, ps_2_x, arbvp 1, vs_1_1, ps_1_1, fp 20, etc. . . ): cg. Create. Program(), cg. Get. Program. String(), etc. . . Manage program parameters: Iterate through the parameters: cg. Get. First. Parameter(), cg. Get. Next. Parameter(), etc. . . Get parameter information: type, semantic, register, . . . Handle errors: cg. Get. Error(), cg. Set. Error. Callback(), etc. . .

Direct 3 D Cg Runtime: Minimal Interface Does not make any Direct 3 D call Allows you to translate the information obtained through the Core Runtime to Direct 3 D data structures, so that you can: Create a Direct 3 D vertex declaration from the Cg program: cg. D 3 D 9 Get. Vertex. Declaration() Validate a Direct 3 D vertex declaration against the Cg program: cg. D 3 D 9 Validate. Vertex. Declaration() and create a Direct 3 D vertex or pixel shader from the Cg program

Direct 3 D Cg Runtime: Expanded Interface Makes the necessary Direct 3 D calls for you Allows you to: Pass the Direct 3 D device: cg. D 3 D 9 Set. Device() Load a program into Direct 3 D: cg. D 3 D 9 Load. Program() Tell Direct 3 D to render with it: cg. D 3 D 9 Bind. Program() Set parameter values: cg. D 3 D 9 Set. Uniform(), cg. D 3 D 9 Set. Uniform. Array(), cg. D 3 D 9 Set. Texture(), etc. . . Output debug information by using the Cg Runtime debug DLL

Open. GL Cg Runtime Makes the necessary Open. GL calls for you Allows you to: Load a program into Open. GL: cg. GLLoad. Program() Enable a profile: cg. GLEnable. Profile() Tell Open. GL to render with it: cg. GLBind. Program() Set parameter values: cg. GLSet. Parameter{1234}{fd}{v}(), cg. GLSet. Parameter. Array{1234}{fd}(), cg. GLSet. Texture. Parameter(), etc. . .

Learning the Runtime The documentation is in: Windows: C: Program FilesNVIDIA CorporationCgdocs Linux: /usr/share/doc/Cg It includes: A Using the Cg Runtime Library chapter from the Cg User’s Manual pages for every function Source code examples are in: Windows: C: Program FilesNVIDIA CorporationCgexamples Linux: /usr/local/Cg/examples They include self-contained Direct 3 D and Open. GL examples

Questions, comments, feedback? Cyril Zeller, czeller@nvidia. com For Cg support Go to developer. nvidia. com/Cg Go to www. cgshaders. org Email cgsupport@nvidia. com