Re: pfIsectFunc() and pfSegsIsectNode()

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Kowsik Guruswamy (kowsik++at++buggy.coryphaeus.com)
Tue, 15 Aug 1995 09:11:08 -0700

On Aug 15, 10:39am, Keith Fry wrote:
> Subject: pfIsectFunc() and pfSegsIsectNode()
> I'm using my own intersection function in the ISECT process to call
> pfSegsIsectNode() multiple times on different pfSegSets. According to
> the pfSegsIsectNode() man page:
>
> "The pfHit objects come from an internally maintained pool and are reused
> on subsequent requests. Hence, the contents are only valid until the next
> invocation of pfSegsIsectGSet in the current process. They should not be
> freed by the application."
>
> Is this statement valid even when calling pfSegsIsectNode() inside the
> intersection function in the ISECT process? Or do these pfHits get reused
> only after the next pfFrame() (which calls my intersection function)?

The pfHit information is valid until the next call the pfSegsIsectNode(), just
like the man pages say. So you should be able to call this multiple times with
different pfSegSets.

> If the statement is true, how can I pass the pfHit data up to the APP
process?
> Can I make a copy of the pfHit structure(s)?

You can use shared memory to pass the data back to the APP process. You can
either frame stamp the intersection data or set up synchronization semaphores
to prevent the ISECT process from writing the data while the APP is processing
it.

K.

-- 
kowsik++at++coryphaeus.com

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