[Gem] Re: pd/gem viz

umläute zmoelnig at iem.kug.ac.at
Tue Jan 23 11:30:55 CET 2001

Jörg Dieß wrote:
> halo list.
> a little piece done with pd/gem in one real time:
> www.testphase.at/viz
> select: sproose
> rtx q:
> in the downloaded patch gwin.pd there is an object called 'nop'
> my pd 'couldn't create'.
> when i connect 'create,1' directly to 'gemwin' and click the new-message
> my screen becomes blue with white letters on it. is this correct?
ok. i think i answered this in my first mail (had to leave the
workstation i was sitting at...)
if your screen becomes blue with white letters on it, this looks somehow
like a your video in. make sure you have a camera connected to your
capture card.
make sure that everything works (see below).
make sure that your camera is sending something meaningful to your
if you hold your camera steadily, you will see what you're shooting
(though somehow shifting).
if you move your camera or something appears to be moving in your focus,
you will notice some rtx-transformation.

btw: i am glad to hear of some problems with rtx. i hope, that any
questions, ideas, problems and things are sent to me (either directly or
via the list).
as indicated before, next week i am going to put a more useable version
on the web.

> pix_video q:
> should this work in the current release?
> pd says: pix_video: connected at x:..
> but when i start rendering pd crashes.
> (i am working under w2k)

how did you manage to make pix_rtx work if pix_video crashes all the
time ?
maybe you notice in the rtx.pd patch that a "dimen" message is sent to
the pix_video objects.
this is quite important, since pix_video will connect to the best
resolution offered (on my machine this 320x240 @ 24bit). Unfortunately
only images with dimensions that are power of 2 can be textured to
anything. (this should be no problem if you are using the "pix_draw"
object, but i never try this because it is so SLOW - using nvidia's
geForce that is providing native openGL but the pixdraw-routines.)
So the size of the image has to be adjusted somehow to be a power of 2
(eg: 320x240 can be truncated to 256x128 (this is what i do in the
rtx.pd patch)). you should not try to connect with resolutions higher
than those provided (256x256 will not work !).
this is really important, for it will *surely* crash your machine when
the second frame is captured. (yess, pix_resize only works once ! -
simply inferior)

[by the way  : Mark, there is a bug in the powOfTwo()-function. if you
are passing it a number k=2^n it will surely return 2^(n+1) - due to a
"<=" instead of "<" in line ??? the shifting will be executed one time
too often. at least i think this is a bug]

i have done therefore a "pix_texture2"-object that will texture images
of any size correctly (as long as you don't use the pix_coordinate) and

i will but this on my web-server next week too.

> just,
> joreg.
> [wannabe]

simply superior


ps: Mark said, that it would be able to compile gem-objects separately
from gem so you could load them afterwards (just like externals are
loaded into pd)
alas, i didn't manage to do so  any hints ?
pps: well, i did manage to compile it, but it didn't load then (sthg
like "could not find \"pix_rtx_setup()\" : failed..."). any hints ?

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