Re: radar simulation

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Ran Yakir (rany++at++rea1.bvr.co.il)
Thu, 20 Apr 1995 11:55:46 +0000

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> > We have a customer who needs to connect and Indy to a some sort of
> > radar equipment. Old fashioned as they are they want to simulate
> > the old kind of display. You know, phosphor that glows for a while
> > and then drops in intensity. Would this be a job for performer
> > or is there other tools more suitable for this ?
> > We would be very grateful for any kind of hints in this direction.
>
> My view is that performer doesn't have a lot to offer this kind of
> application.
>
> I'd try GL (orthographic projection) with asynchronous updates to fading
> objects on the radar display with a complete redraw only along the sweep
> line. This would avoid clearing the framebuffer (probably your biggest
> overhead in this type of application) and drawing the whole scene every
> frame and it could still be double buffered if required.
>

I think that the most appropriate solution for radar blips fading on an INDY
would be to use color maps. You may not need doublebuffering if you do so, so
you'll exploit your INDY's bitplanes better. You might even end up with 8
bitplane INDY. What you should do is divide the time range from the birth of a
blip to its death, into 256 (or any other amount of colors less than 256). You
than set up your colormap to have shades of green, ranging from total dark to
bright green. Each new blip will get a color according to its birth time in the
total 256 time-slots cycle. On each cycle, you offset the colormap values by
one.
I propobaly haven't thought of all the possible problems here, but the approach
might work.

Good luck

Ran

-- 
 __                                  | Ran Yakir
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Maybe in reply to: David Luebke: "postCull callbacks aren't being called"

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