X Window System

[cl_5]

Hi forumers,

a programmer ask me about X11 and I have no answer. Can anybody help me. I post the question as follows:

I need help to understand exactly what triggers the creation of the
X visuals when a HP workstation is booted.
It seems that the file X0screens is the trigger for that but that is not
very clear for me.

If this file contains only the line
Screen /dev/crt
it looks like several visuals are created (after a reboot), that means
I have 3 or 4 PseudoColor visual + 1 DirectColor visual + 1 or 2 TrueColor
visuals. It seems that the default visual is a PseudoColor visual.
Where are defined these visuals and the default one ?
For PseudoColor visuals, it looks like like there are doubled, and it looks
like the difference is relative to the DOUBLE-BUFFER perflevel. Do you
know the difference ?
When the default visual has a perflevel equal to 1, I noticed that the
refresh of CAS graphics is very sloiw.

Second big question is relative to the following line we need currently to
add in the X0screens to make CAS working correctly:
ScreenOptions DisableDefaultCmapTransparency
Without this parameter, the color allocation in the default colormap fails
My hypothesis is that this parameter allows to reduce the number of allocated
colors in the default colormap before trying to start CAS. Is it correct ?
The problem could be that, as soon as I add this screen option, then I have
only 2 PseudoColor visuals and no more a TrueColor visual. Do you know why ?

Thanks in advance

Carsten

[RolandH]

Hi Carsten,

give that link to your developer.
http://www.docs.hp.com/hpux/11.0/index.html

Go to the CDE section.
He should pick what he need !!

Roland

[Mike Stroyan · Accepted solution]

The X server on HP-UX usually presents as many visuals as it can to allow access to all the features a graphics card provides. That varies for different graphics cards. The specific visuals and options supported by various cards are listed in chapters 4 and 5 of the "Graphics Administration Guide for HP-UX 11.x", available from
http://h20000.www2.hp.com/bc/docs/support/SupportManual/lpv38356/lpv38356.pdf

You can affect which visuals are available by setting options with SAM or by editing X0screens (or XF86Config for FireGL-UX and newer cards). There is no direct list of visuals in X0screens, but some options will affect available visuals and which visual is used as the default.

Different visuals are used for specific OpenGL features. It is common to have visuals for overlay planes and image plains, with single buffered and double buffered visuals. Some will look alike to plain X11 programs. There is a utility in /opt/graphics/OpenGL/contrib/xglinfo that you can build an run to report the OpenGL specific features of all the visuals on an X server.

The DisableDefaultCmapTransparency option is an extreme fix for applications that absolutely insist on getting many colors from the default colormap. The color index 255 is normally reserved on the Visualize-FXE for a transparent color into the image planes where the TrueColor visuals reside. The option releases that color index to colormaps in the default visual. There is then no transparent color available for showing through to the image plane visuals.