[PD] scaling pix_draw in GEM ,and GEM performance question

chris clepper cclepper at artic.edu
Tue Sep 10 20:10:49 CEST 2002

I second guenter's post about not having hardware GL working.  did 
you get the nvidia drivers off the nvidia site?  the ones that come 
with the linux distros are not the real drivers.

also, what size are these textures?  and how many do you have?  you 
could be running out of vram if you are trying to use a lot of large 

you are obviously using a laptop (geforce2go) so the hard drive could 
be slowing you down if it is full or you are trying to load massive 
amounts of data like 640x480 uncompressed movies or lots of files at 
once.  also i find that sometimes dma transfers are off by default in 
linux.  check man hdparm and 
http://linux.oreillynet.com/pub/a/linux/2000/06/29/hdparm.html for 
more info.  this can make a big difference in disk transfer speed.

as far as the image distortion goes, this could be a case of resizing 
the texture to a power of two.  i'm pretty sure that GEM supports 
non-power of two textures tho...

for resizing: mapping the movie onto a quad and resizing/scaling the 
quad should be the fastest method.


>I am having trouble scaling images using pix_draw. I thought I could 
>scale an image using scale or scaleXYZ before pix_draw but it seems 
>like these objects   have no effect. I can scale an image by texture 
>mapping onto a square and resizing it but I find it is slower than 
>pix_draw in this case. When rendering movies I've found  that 
>texture mapping is faster but the image is more distorted. I'm using 
>GEM 0.87 under Linux. Is this a problem with pix_draw or is it 
>supposed to work this way? I have a fast processor ( 1 GHz) a good 
>video card (Nvidia 2Go) and I find movies are playing  quite slowly. 
>I only have 128 MB ram. Just ordered another 256 MB hoping this will 
>speed things up. Wondering what other people are using to get 
>realtime playback with MPEGs in Linux?
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>PD-list at iem.kug.ac.at


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