Name 

    EXT_gpu_program_parameters 

Name Strings 

    GL_EXT_gpu_program_parameters 

Contributors

   Pat Brown
   Haroon Sheikh
   
Contact 

    Pat Brown, NVIDIA Corporation (pbrown 'at' nvidia.com) 
    Geoff Stahl, Apple Computer, Inc. (gstahl 'at' apple.com)

Status 

    DRAFT SPECIFICATION 

Version 

    Last Modified Date:         06/02/06 
    Revision:                   2 

Number 

    320 

Dependencies 

    ARB_vertex_program or ARB_fragment_program is required. 

    This specification is written against the spec language from the 
    ARB_vertex_program extension. 

Overview 

    This extension provides a new set of procedures to load multiple 
    consecutive program environment parameters more efficiently, via a single 
    GL call instead of multiple calls.  This will reduce the amount of CPU 
    overhead involved in loading parameters. 

    With the existing ARB_vertex_program and ARB_fragment_program APIs, 
    program parameters must be loaded one at a time, via separate calls. 
    While the NV_vertex_program extension provides a set of similar functions 
    that can be used to load program environment parameters (which are 
    equivalent to "program parameters" in NV_vertex_program), no such function 
    exists for program local parameters. 

New Procedures and Functions 

    void ProgramEnvParameters4fvEXT(enum target, uint index, sizei count, 
                                   const float *params); 

    void ProgramLocalParameters4fvEXT(enum target, uint index, sizei count, 
                                     const float *params); 

New Tokens 
    
    None. 

Additions to Chapter 2 of the OpenGL 2.0 Specification (OpenGL Operation) 

    (modify ARB_vertex_program, add paragraph after introduction of 
    ProgramEnvParameter* calls) 

    The command 

        void ProgramEnvParameters4fvEXT(enum target, uint index, sizei count, 
                                       const float *params); 

    updates the values of the program environment parameters numbered <index> 
    through <index> + <count> - 1 for the given program target <target>. 
    <params> points to an array of 4*<count> values, where the first four are 
    used to update the program environment parameter numbered <index> and the 
    last four update the program environment parameter numbered <index> + 
    <count> - 1.  The error INVALID_VALUE is generated if <count> is less than 
    or equal to zero or if the sum of <index> and <count> is greater than or 
    equal to the number of program environment parameters supported by 
    <target>. 

    (modify ARB_vertex_program, add paragraph after introduction of 
    ProgramLocalParameter* calls) 

    The command 

        void ProgramLocalParameters4fvEXT(enum target, uint index, sizei count, 
                                         const float *params); 

    updates the values of the program local parameters numbered <index> through 
    <index> + <count> - 1 belonging to the program object currently bound to 
    <target>.  <params> points to an array of 4*<count> values, where the 
    first four are used to update the program local parameter numbered <index> 
    and the last four update the program local parameter numbered <index> + 
    <count> - 1.  The error INVALID_VALUE is generated if <count> is less than 
    or equal to zero or if the sum of <index> and <count> is greater than or 
    equal to the number of program local parameters supported by <target>. 

Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization) 

    None. 

Additions to Chapter 4 of the OpenGL 2.0 Specification (Per-Fragment 
Operations and the Frame Buffer) 

    None. 

Additions to Chapter 5 of the OpenGL 2.0 Specification (Special Functions) 

    None. 

Additions to Chapter 6 of the OpenGL 2.0 Specification (State and 
State Requests) 

    None. 

Additions to Appendix A of the OpenGL 2.0 Specification (Invariance) 

    None. 

Additions to the AGL/GLX/WGL Specifications 

    None. 

GLX Protocol 

    Four new GL commands are added.  The following commands are sent to the 
    server as part of a glXRender request: 

        ProgramEnvParameters4fvEXT 
            2           16+16*n         rendering command length 
            2           4281            rendering command opcode 
            4           ENUM            target 
            4           CARD32          index 
            4           CARD32          n 
            16*n        FLOAT32         params 

        ProgramLocalParameters4fvEXT 
            2           16+16*n         rendering command length 
            2           4282            rendering command opcode 
            4           ENUM            target 
            4           CARD32          index 
            4           CARD32          n 
            16*n        FLOAT32         params 

Errors 

    INVALID_VALUE is generated by ProgramEnvParameters4fvEXT or 
    ProgramLocalParameters4fvEXT if <count> is less than or equal to zero. 

    INVALID_VALUE is generated by ProgramEnvParameters4fvEXT if <index> plus 
    <count> is greater than or equal to the number of program environment 
    parameters supported by <target>. 

    INVALID_VALUE is generated by ProgramLocalParameters4fvEXT if <index> plus 
    <count> is greater than or equal to the number of program local parameters 
    supported by <target>. 

New State 

    None. 

Issues 

    (1) Should a set of ProgramEnvParameters*EXT() calls be added, or is using 
        NV_vertex_program's ProgramParameters*NV() sufficient? 

      RESOLVED:  We should add an ARB-style ProgramEnvParameters*() call for 
      naming consistency. Also ProgramParameters*NV() are not available on 
      all platforms.

    (2) Should an equivalent set of calls be added to query multiple program 
        parameters at once? 

      RESOLVED:  No. 

    (3) Should double-precision versions be supported? 

      RESOLVED:  No.  Double-precision parameter values will be converted to 
      single-precision in current driver implementations, anyway. 

Revision History 

    Rev.    Date    Author    Changes 
    ----  --------  --------  -------------------------------------------- 
    2     06/02/06  haroon    Changed to EXT. Added contributors.
    1     04/24/06  pbrown    Initial revision.