Re: pfFrust Questions
Salvador Cabaruvias (sal++at++marge.mdc.com)
Wed, 14 Dec 1994 13:41:04 -0800
On Dec 5, 2:57pm, John Rohlf wrote:
> Subject: Re: pfFrust Questions
> >
> > To: info-performer++at++sgi.com
> > Subject: pfFrust Questions
> > ---text follows this line---
> > Hi, I'm new to Performer. We are running Performer 1.2 on Onyx with 6 cpus
> > and 2 graphic pipes with 2 RM5s per pipe. We are using the Onyx to be our
OTW
> > image generator for our C17 simulator.
> >
> > The setup is a 2 channel system with the pilot and copilot sharing the same
> > front channel and the pilot having a separate side view channel. We are
> > using a wide angle collimated optics (WACO) system with the pilot side
having
> > zero gap mirrors for his front and side views (two channels).
> >
> > Now for my question:
> >
> > The WACO system has 45 degrees HFOV (hortizontal fiew of view) and 36 VFOV
> > (vertical fiew of view). In addition, there is a 3 degree pitch in the
> > VFOV to provide more down view angle.
> >
> > Using the pfMakeSimpleFrust and pfChanViewOffsets, I can setup the two
> > channels but I can't account for the 3 degs of pitch. The way it's
explained
> > to me, is that 36 VFOV is +25 from the center and -31 down. Using the
> > pfChanViewOffsets to add in the 3 degs simply makes a side window that is
> > pitched down 3 degrees. This is not the affect I want. I want the window
> > to stay at the original center line but with more down viewing angle. This
> > is critical since we are using a real HUD. When we on the runway, the
horizon
> > is not where it should be when viewing thru the HUD with/out the 3 degs
> > using the pfChanViewOffsets command.
> >
> >
> > Has anyone done this before? Would you mind pointing me in the right
> > direction? What are the calculations/calls I need to get this to align up?
> >
> > Thanks in advance,
> >
> > sal
> >
> >
> >
> >
-----------------------------------------------------------------------------
> > Salvador Cabaruvias |email: sal++at++sgidev.mdc.com
> > CSSL |saying: "Well I be done seen about
> > McDonnell Douglas | everything when I see elephant
> > (310) 593-6719 | fly!" --- Dumbo ---
> >
-----------------------------------------------------------------------------
> >
> >
>
> Try this:
>
> pfFrustAspect(chan, PFFRUST_CALC_NONE); /* Needed to workaround a bug*/
> pfChanAutoAspect(chan, PFFRUST_CALC_NONE);
> pfFrustNearFar(chan, near, far);
> pfMakePerspFrust(chan,
> -near * pfTan(22.5f), /* left */
> near * pfTan(22.5f), /* right */
> -near * pfTan(25.0f), /* bottom */
> near * pfTan(31.0f)); /* top */
>
>
>
>-- End of excerpt from John Rohlf
This did the trick with of course corrections for my math! The actual
parameters were:
24 degs for both horizontals
and 15 degs top Vertical
and 21 degs bottom Vertical
Thanks a bunch,
sal
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on Mon Aug 10 1998 - 17:50:44 PDT