Bernard Leclerc (bleclerc++at++cae.ca)
Mon, 2 Dec 1996 15:57:21 -0500
> I tried this on info-vega, but without much success; I'll try it here
> and see what I come up with.
>
> We're using Vega 2.02 with Performer 2.0 on a RE^2 with 2xRM4 and Irix
> 5.3 and IGL libraries.
>
> Part of our TTPRR includes measuring the size of objects on the
> screen. When we run perfly, the sizes come out correct. When we run
> any Vega application, the objects are too small. The error is not
> linear, but in general the percentage difference is worse the closer
> the object is. (Sizes range from 90.16% to 64.89% of their intended
> size.)
>
> Neither of the windows has a border. The Vega application is a
> minimal thing. I haven't added anything to it but my debugging
> printouts. The perfly code is "mostly" unmodified: I added changes
> for alpha blending in high-quality mode, flimmering fixes, and my
> debugging printouts.
>
> I've printed out the FOV and clip planes in both applications, and
> they match. I've printed the Vega viewing matrix, projection
> matrix, and WorldToScene matrix of the Vega app; all of them are
> trivial orthonormal matrices. I've checked the Vega skew, which is
> 0.0 all through. I'm running out of ideas.
>
> I've set up the Vega .adf file to put a wall at (0, 200, 0). The
> observer is default. When I call perfly, I set the observer at
> (0, -200, 0). The wall fills the screen horizontally in perfly, but
> has plenty of space around it in Vega. (It's easy to see the
> difference without getting out the ruler in this case.)
>
> Anybody know what's going on? Even a suggestion on where to look
> would be helpful.
Jude,
If the viewing parameters are the same in both perfly and your Vega-based
app but you're not seeing the same thing, then I'd say you're not looking
at the same object. Have you examined the scene graph produced by perfly
(the "Show Tree" button on the GUI). Is there a SCS (with a scale factor)
added to your scene by Vega? This is just another direction to look for
the solution to your problem.
--
Bernard Leclerc CAE Electronics Ltd., 8585 Cote De Liesse
Technical Leader Saint-Laurent, Quebec, Canada, H4L-4X4
3-D Graphics Applications tel: +1 514 341 2000 extension 2275
bleclerc++at++cae.ca fax: +1 514 340 5496
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