Name

    SGIX_color_table_index_mode

Name Strings

    GL_SGIX_color_table_index_mode

Version

    $Date: 1997/04/07 20:05:51 $ $Revision: 1.1 $

Number

    XXX

Dependencies

    SGI_color_table affects the definition of this extension

Overview

    Currently the mapping from a color value to an index is defined mathematically as
    clamp your (float) value to [0,1], multiply by the table size-1 and round.

    This is less interesting for an s10e5 format pixel where we would like to use
    "all" the bits as an index, not just the bits that are good in [0,1].

    The answer is to specify that the float color value is converted to the framebuffer
    format and then the high order bits are taken as necessary to index the power of
    two lookup table. In the silly case where the table is larger than the number of
    bits we have, the lsb's of the index are 0 filled.

Issues

    the down and dirty nature of this extension may offend the puritanical sensibilities of
    certain clean minded types.

New Procedures and Functions

   None.

New Tokens

    Accepted by the <pname> parameter of ColorTableParameterivSGI,
    ColorTableParameterfvSGI, GetColorTableParameterivSGI, and
    GetColorTableParameterfvSGI:

	COLOR_TABLE_INDEX_MODE				0xXXXX

    Accepted by the <params> parameter of ColorTableParameterivSGI,
    ColorTableParameterfvSGI

	COLOR_TABLE_BITS				0xXXXX
	COLOR_TABLE_ARITH				0xXXXX

Additions to Chapter 2 of the 1.0 Specification (OpenGL Operation)

    None

Additions to Chapter 3 of the 1.0 Specification (Rasterization)

    if the value of COLOR_TABLE_INDEX_MODE is COLOR_TABLE_BITS then
    XXX Specify that the index is computed by converting the float color value to
    the framebuffer format and taking the required most significan bits as an
    index into the color table.

    if the value of COLOR_TABLE_INDEX_MODE is COLOR_TABLE_ARITH then
    do it like it already says.

Additions to Chapter 4 of the 1.0 Specification (Per-Fragment Operations
and the Framebuffer)
   
    None


Additions to Chapter 5 of the 1.0 Specification (Special Functions)

    None


Additions to Chapter 6 of the 1.0 Specification (State and State Requests)


Additions to the GLX Specification

    None


GLX Protocol

    XXX

Dependencies on SGI_color_table

    If SGI_color_table must be supported to support SGI_color_table_index_mode.

Errors

    XXX incomplete

New State

    Get Value				Get Command			Type	Initial Value		Attribute
    ---------				-----------			----	-------------		---------
    COLOR_TABLE_INDEX_MODE		GetColorTableParameterfvSGI	Z2	COLOR_TABLE_ARITH	pixel

New Implementation Dependent State