GRASS monitor on 24 bit display

[Conn Copas]

Andreas Schmidt writes:
> 
> According to Kenn Gardels:
> > We have modified the GRASS code to work on a 24bit display directly, by checking
> > first for a psuedocolor or truecolor visual.  It works fine on DEC Alpha, but
> > we havn't tested it on other platforms. 
> 
> It works also fine on SUN (SunOS) with 24bit and on LINUX with 24bit 
> and 16bit!
> 
The Irix5.3 system has me mystified, probably because of my hazy notions of
colour, and I would appreciate some pointers. The update5 README suggest there
'may' be glitches in the X driver only. Either that is an understatement, or we
haven't configured the system properly.

The default IRIS visual is reputedly 8 bit pseudo-colour. The 'getplanes' call
suggests there are 2**12 colours available. Floating colormode improves
the appearance of elevation maps. d.colors doesn't work in the sense that
interactive toggling doesn't occur, but colour changes are realised on exit
from the command, even without an explicit save.

Running IRIS and X monitors in tandem, using a fixed colormode, elevation
maps still look better in the IRIS window. Floating colormode prevents any
display in the X window. Setting the IRIS monitor to float will blank out a
previously good X window.

With a remote X window on a Sparc, floating colormode improves elevation maps,
provided there are no other monitors open. d.colors won't toggle, but changes
can be saved explicitly.

A call to RGBmode (true colour) suggests there are an enormous number of
colours available, but the results are bizarre. As they say, a little
knowledge is a dangerous thing. Can anyone set me straight? Secondly, has
anyone followed in the steps of the XDRIVER.OKI in order to get better
performance on a SGI?

-- 
Conn V Copas
Information Technology Division
Defence Science and Technology Organisation
PO Box 1500
Salisbury            tel: +61 (0)8 25 95349
SA  5108             fax: +61 (0)8 25 96781
Australia       e-mail: cvc at itd.dsto.gov.au
-------------------------------------------