[Visualpython-users] label (text) on Linux

[Bruce S. <ba...@an...>]

One of the high-priority VPython bugs is that the "label" object for 
displaying text does not exist in the Linux version. Among other things, 
this makes the autoscaled graphing be unusable. Is it possible that there 
is someone in the VPython user community who is sufficiently knowledgeable 
in Linux to be able to help with this? We are short of this resource at the 
moment.

A main component of the problem is simply choosing a font. Here are some 
notes from students who looked at the problem earlier in the semester but 
ran out of time to devote to it.

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On Unix, an analogous function glXUseXFont() is available.  However, we 
have been using the (higher level) GTK-GLArea widget instead of writing 
directly to glX.  GTK-GLArea seems to only provide a draw_text() function, 
not a way to obtain fonts.

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From Ari: unfortunately, i can't even compile, due to an evil name 
conflict: X uses the name 'Display' to refer to an X display; we use 
Display internally as well. I played with trying to #define one away from 
the other, but the modules are too interlinked -- i always end up hitting 
both of them. short of massively reordering the include structure, i'm not 
sure it's practical.

Xlib.h typedef's struct _XDisplay to Display. Xlib is pulled in by glx.h 
which is needed by our xgl.h. But you can't move xgl.h ahead of the stuff 
that pulls in our display.h (i.e. say from the first to the 2nd line of 
arrow.cpp) because we need the other core Visual headers so we know what a 
glcontext is and stuff .... yuck.

before i go doing anything drastic (like renaming everyplace we use 
Display, or putting it in the namespace Visual or something like that) i 
wanted to consult with Scherer. Do you want me to check my stuff in, even 
tho it's broken?

it's likely also to have font-naming errors, since X will probably want an 
evil X long named font 
('adobe-courier-bitstream-foundry-10-*-1-1-2-3-5-*-=|:-)}-abe-lincoln'). i 
*think* it might work where i just try to load 'fixed' (since X seems to 
like to do that in other cases where i specify names that don't exist) but 
we'll see. i don't have any real docs on glX calls, except Sun's online 
manpages (which are pretty thin at best). Mesa doesn't bother with 
documentation :) and the only statement in the red book about glXUseXFont 
is that it exists (i could *really* use a working example). the Linux X 
call docs aren't bad tho ... i think everything else in there will work 
right.