Limitations in OGL control

[ArnO 57]

Hi,

I'm using CVI 5.5 and OpenGL functions. I have some huge data to plot that is to say 100x100 arrays. There is no problem for the representation but CVI crashes when I want to manipulate (Rotate..) the OGLCtrl. It seems that above 36x36 it crashes with this message :
The program has caused a 'General Protection' fault at 0177:1000F8E4"

I can represent big datas array (more than 100x100) but the manipulation is not possible.

Any idea ?

Thanks

[Jason F.]

I have tried reproducing the behavior you described by plotting an array with even up to 500 by 500 indices of data with the
...\cvi\samples\userint\custctrl\cviogl\simple.prj example and it never creates a General Protection Fault. Albeit, it does run very very slowly when you try to rotate the graph, but it never GPFs.

I think that this slowing behavior may be the key in to what is causing yours to GPF, in that when you increase the amount of data you are plotting to the cviogl control it definitely requires you system to have the amount of RAM and underlying graphics device support to handle the amount of data and number of polygons being plotted to the control.

What are your system specs, i.e. CPU, amount of RAM, video card brand/type/amount of onboard
RAM? My system is a PIII 550, 256MB of RAM, with an AGP Nvidia Vanta TNT2 with 8MB of RAM. Do you have another system that you could possibly try this on to see if the same behavior exists? Can you try the aforementioned project with the change in the amount of data you specified to see if this program behaves the same?

Jason F.
Applications Engineer
National Instruments
www.ni.com/ask

[ArnO 57]

Thank you for your answer Jason but I found the solution. The problem was the setting at FALSE of OGLATTR_COPY_ORIGINAL_DATA that causes the GPF. When it is set at TRUE all work fine whereas et FALSE it causes the GPF for large (40x40) data array.

ArnO