NAME
    vp40 - OpenGL vertex profile for NV4x (GeForce 6xxx and 7xxx Series,
    NV4x-based Quadro FX, etc.)

SYNOPSIS
      vp40

DESCRIPTION
    This OpenGL profile corresponds to the per-vertex functionality
    introduced by the GeForce 6800 and other NV4x-based NVIDIA GPUs.

    The compiler output for this profile conforms to the assembly format
    defined by NV_vertex_program3 and ARB_vertex_program.

    Data-dependent loops and branching *are* allowed.

    Relative indexing of uniform arrays *is* supported.

    Texture accesses are supported. However substantial limitations on
    vertex texturing exist for hardware acceleration by NV4x hardware.

    NV4x hardware accelerates vertex fetches only for 1-, 3-, and
    4-component floating-point textures. NV4x hardware does not accelerated
    vertex-texturing for cube maps or 3D textures. NV4x does allow
    non-power-of-two sizes (width and height).

3D API DEPENDENCIES
    Requires OpenGL support for the NV_fragment_program3 extension. These
    extensions were introduced by the GeForce 6800 and other NV4x-based
    GPUs.

  OpenGL Extension Specifications

     http://www.opengl.org/registry/specs/NV/vertex_program3.txt 
     http://www.opengl.org/registry/specs/ARB/vertex_program.txt 

PROFILE OPTIONS
    PosInv=*val*
        Non-zero means generates code for position-invariant (with
        fixed-function) position transformation.

    NumTemps=*val*
        Maximum number of temporary registers the implementation supports.
        Set to the implementaiton-dependent value of
        "GL_MAX_NATIVE_TEMPORARIES_ARB" for best performance.

    MaxAddressRegs=*val*
        Maximum number of address registers the implementation supports. Set
        to the implementaiton-dependent value of
        "GL_MAX_NATIVE_ADDRESS_REGISTERS_ARB" for best performance.

    MaxInstructions=*val*
        Maximum number of instructions the implementation supports. Set to
        the implementaiton-dependent value of
        "GL_MAX_NATIVE_INSTRUCTIONS_ARB" for best performance.

    MaxLocalParams=*val*
        Maximum number of local parameters the implementation supports.

DATA TYPES
    float
        This profile implements the float data type as IEEE 32-bit single
        precision.

    half
    double
        "half" and "double" data types are treated as "float".

    int The "int" data type is supported using floating point operations,
        which adds extra instructions for proper truncation for divides,
        modulos and casts from floating point types. Because integer values
        are simulated with IEEE single-precision floating-point, they are
        accurate over the range -2^24 to 2^24 but will not overflow like
        true integers.

    fixed
    sampler*
        This profile does not support any operations on the "fixed" or
        "sampler"* data types, but does provide the minimal *partial
        support* that is required for these data types by the core language
        spec (i.e. it is legal to declare variables using these types, as
        long as no operations are performed on the variables).

SEMANTICS
  VARYING INPUT SEMANTICS

    The set of binding semantics for varying input data to vp40 consists of
    POSITION, BLENDWEIGHT, NORMAL, COLOR0, COLOR1, TESSFACTOR, PSIZE,
    BLENDINDICES, and TEXCOORD0-TEXCOORD7. One can also use TANGENT and
    BINORMAL instead of TEXCOORD6 and TEXCOORD7.

    Additionally, a set of binding semantics ATTR0-ATTR15 can be used. These
    binding semantics map to NV_vertex_program3 input attribute parameters.

    The two sets act as aliases to each other on NVIDIA GPUs excluding Apple
    Macs. ATI GPUs and NVIDIA Mac GPUs do *not* alias the conventional
    vertex attributes with the generic attributes.

      Binding Semantics Name        Corresponding Data
  
      POSITION, ATTR0              Input Vertex, Generic Attribute 0 
  
      BLENDWEIGHT, ATTR1           Input vertex weight, Generic Attribute 1 
  
      NORMAL, ATTR2                Input normal, Generic Attribute 2
  
      DIFFUSE, COLOR0, ATTR3       Input primary color, Generic Attribute 3
  
      SPECULAR, COLOR1, ATTR4      Input secondary color, Generic Attribute 4
  
      TESSFACTOR, FOGCOORD, ATTR5  Input fog coordinate, Generic Attribute 5
  
      PSIZE, ATTR6                 Input point size, Generic Attribute 6
  
      BLENDINDICES, ATTR7          Generic Attribute 7
  
      TEXCOORD0-TEXCOORD7,         Input texture coordinates (texcoord0-texcoord7)
      ATTR8-ATTR15                 Generic Attributes 8-15

      TANGENT, ATTR14              Generic Attribute 14

      BINORMAL, ATTR15             Generic Attribute 15

  UNIFORM INPUT SEMANTICS

      C0-C255           Constant register [0..255].
                        The aliases c0-c255 (lowercase) are also accepted.

    If used with a variable that requires more than one constant register
    (e.g. a matrix), the semantic specifies the first register that is used.

      TEXUNIT0-TEXUNIT15  Texture unit (but only 4 distinct texture units
                          are allowed)

  OUTPUT SEMANTICS

      Binding Semantics Name        Corresponding Data
  
      POSITION, HPOS                Output position
  
      PSIZE, PSIZ                   Output point size
  
      FOG, FOGC                     Output fog coordinate
  
      COLOR0, COL0                  Output primary color 
  
      COLOR1, COL1                  Output secondary color
  
      BCOL0                         Output backface primary color
  
      BCOL1                         Output backface secondary color
  
      TEXCOORD0-TEXCOORD7,          Output texture coordinates
      TEX0-TEX7
  
      CLP0-CL5                      Output Clip distances

STANDARD LIBRARY ISSUES
    Standard library routines for texture cube map and rectangle samplers
    are not supported by vp40.

