Hi @ all !
First of all, i should mention that i use QT for coding my C/C++ application, because maybe it has sth. to do with the following issue(s).
The point is that i must use several widgets/contexts/windows at the same time. (These windows contain live video streams, 2D- and 3D Plots, etc ...)
But in one "final" MAINwindow the contents of (nearly) all other windows should appear.
The first approach was to use PixelBuffers - the QT-implementation ( just mentioning because i wonder if it makes a difference ? )
So, i created a PixelBuffer for each widget/context and let these PBuffers update the corresponding texture (size=[512, 512]) in a shared Context, the MAINwindow.
On a Core2Duo with a Geforce8800 and Ubuntu that worked - allthough the CPU-usage was pretty high ~50%
But on a Laptop (Core2Duo, Geforce7600Go and with WinXp) it was ... unusable
The second approach was about using Framebuffers. Just the same way as with PBOs. (I think *scapingMyHead* i only gave it a try on the Laptop - with no better result)
Then i thought about not creating a texture to display in the MAINwindow, but passing it some displaylists.
But that's a no go, as the displaylists have to be calculated again and again ... as the data/vertices and stuff change from frame to frame
So, my last approach was to create VBOs (=Vertex Buffer Objects) and pass them, respectivly the identifier of the VBOs to the MAINwindow.
And that's now where I'am stuck ....
After adding glew and having some trouble ... I managed to get it runnning and did a test, to see how far i can go ...
Basically I draw the same VBO ten times at different positions in the scene and the CPU-usage increased to ~60%.
Further i also tried to create and draw ten VBOs with the same data but independent memory - same result
Note: to draw the VBO only once in a scene the CPU-usage was ~0%
I wonder if this a typical behaviour, or if i might do sthg. wrong ?
The VBO is not big .. ~0,2 MB (for ~4000 Vertices)
To make it short: Could anybody please give me an advice of <u>how to draw the contents of several widgets/windows/contexts additionally to there origin windows in a MAINwindow ?</u> - in the fastest and less exhausting way ?!
Hope it got clear what i mean ... if not, please just ask