On Wed, 3 Apr 2002, Dr Andrew C Aitchison wrote:
> On Tue, 2 Apr 2002, Thruput Limited wrote:
>
> > Dear All,
> >
> > This is a repeat of a requirement from earlier this year.
> >
> > You are quite right the matrox card does support 8 bit Psuedocolor.
> >
> > When I requested before my problem is that I need two psuedocolor visuals.
> >
> > It was suggested that the second one could be done in software. This means
> > remapping the second psuedocolor one of the truecolou visuals.
You can't do that. In X terminology you'd have to map a PseudoColor
one through a DirectColor visual. In the overlay mode on MGA, there
is no DirectColor.
> >
> > Also I have read the manual on the G400 hip set (670pages) and the no
> > reference to psuedocolor Color Lookup Tables. Where is this the CLUT
> > situated?
>
> Are you are looking at the Matrox MGA-G400 Specification,
> Document Number 10617-MS-0101 June 2, 1999 (if you need it,
> XFree86 have this document, but I don't know whether it was obtained
> under a non-disclosure agreement - check with Davis Dawes) ?
> That document calls it a palette or LUT. There are at least two palettes;
> you want the one described in chapter 4.7, not the texture palette.
> You are interested in Direct Color Mode (BPP32DIR), which is already
> used when option "overlay" is used.
> You need to use a software LUT to convert each 8bit value into
> 24bits which you write into the memory currently used by the TrueColor
> visual (X interchanges the names "TrueColor" and "DirectColor" with
> respect to the chip document :-).
The software lut is already used for the 8 bit PseudoColor
visuals. There isn't another one for X's DirectColor, which is
why the server doesn't offer DirectColor visuals (or gamma correction
outside of the 8 bit planes) in that mode.
You can't have two simultaneous PseudoColor palettes loaded on
hardware with only one hardware palette.
Mark.
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