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This step applies only to color index groups.
If the GL command that invokes the pixel transfer operation requires
that RGBA component pixel groups be generated,
then a conversion is performed at this step.
RGBA component pixel groups are required if
If RGBA component groups are required,
then the integer part of the index is used to reference 4 tables of
color components: PIXEL_MAP_I_TO_R, PIXEL_MAP_I_TO_G,
PIXEL_MAP_I_TO_B, and PIXEL_MAP_I_TO_A.
Each of these tables must have entries for some integer value of n
(n may be different for each table).
For each table,
the index is first rounded to the nearest integer;
the result is ANDed with ,
and the resulting value used as an address into the table.
The indexed value becomes an R, G, B, or A value, as appropriate.
The group of four elements so obtained replaces the index,
changing the group's type to RGBA component.
- The groups will be rasterized, and the GL is in RGBA mode, or
- The groups will be loaded as an image into texture memory, or
- The groups will be returned to client memory with a format other
If RGBA component groups are not required,
and if MAP_COLOR is enabled,
then the index is looked up in the PIXEL_MAP_I_TO_I
table (otherwise, the index is not looked up).
the table must have entries for some integer n,
and the integer part of the index is ANDed with ,
producing a value.
This value addresses the table,
and the value in the table replaces the index.
The floating-point table value is first rounded to a fixed-point
value with unspecified precision.
The group's type remains color index.
Sat Mar 29 02:23:21 PST 1997