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Re: IDL and OpenGL [message #56447 is a reply to message #17065] Wed, 31 October 2007 09:29 Go to previous messageGo to previous message
Karl Schultz is currently offline  Karl Schultz
Messages: 341
Registered: October 1999
Senior Member
It would probably be wise to profile your application to determine
where the time is being spent. It would be unwise to go through
a lot of effort to replace the display subsystem when the problem
might be elsewhere.

You can use IDL's profiler or use SYSTIME to check suspected hotspots.

If the Window Draw method ends up being the one using all the time, then
perhaps you are sending too much geometry or have too complex of a scene.
You might consider adjusting the fineness of your meshes according
to the view.

If tiling is the bottleneck, consider using a tiling server running
in another process. This will at least let the main app run smoother
without stalling while waiting for tiles.

Object Graphics is a fairly thin layer over OpenGL and so there are
not many places where IDL slows things down for OpenGL. But you might
be able to do better by accessing some of OpenGL's features that IDL
doesn't use. Compiled vertex lists (VBO's) are an example, but I
do not know if IDL uses them or not.

Finally, and this is NOT recommended, you can make OpenGL calls using
the same IDLgrWindow and OpenGL context via C code. You start by making
a subclass of IDLgrModel and override the Draw method. Your Draw method
can then call C code that can make OpenGL drawing calls. The dicey part
of this is that the IDL internals can change from release to release
and something like this that worked in one release may not in another.
But it is a good way to prototype something to see if you are on the
right path.

Karl

Gaurav <selfishgaurav@gmail.com> wrote:
> Hi all,
> I have been using IDL to develop a Google Earth type application for
> the past one year and have been pretty successful in doing so. But the
> application is not as fast as I would like it to be. I believe I have
> removed all the programming bottlenecks that might slow my program
> down(Avoiding loops, using small tiles of images etc..ad infinitum). I
> was wondering if leaning more on OpenGL might be of some help.
>
> Now, I am aware that IDL already uses OpenGL for many of its tasks-but
> exactly what tasks it does using OpenGL is not transparent (at least
> to me). Can anyone suggest me ways to get on if I want to acess the
> OpenGL library of functions using IDL-the way they do it using C, C++,
> VB or VB.NET.
>
> I would like to keep my discussion open ended and would welcome any
> advice related to the matter-be it OpenGL+IDL or makeing my program
> faster otherwise.
>
> Cheers!
> Gaurav
>

--
Karl Schultz kws@frii.com
There are 844,739 ways to enjoy a Waffle House hamburger.

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