Re: [Plib-users] Problem with rotations

[Ben W. <za...@ec...>]

Hello Steve..

Ya, I don't have a problem with that.. It seems to be sgMakeRotMat(mat,
h,p,r) where pitch is set to something other then 0. Then I converted it
back to sgCoord and used transform, although in my code, I also tried just
using the matrix and it did the same thing. Try coping the file that I sent
over tux_example.cxx and see that happens. If you go back to the code in the
update_motion function and user the header or the role things work fine, but
pitch causes problems. I will keep looking for the problem, but I can't find
it, when I seperated into tux_example (so its not something in my
applicaton) and it only happens with pitch (header and role are fine) then I
don't know what else it could be.

Ben

----- Original Message -----
From: "Steve Baker" <sjb...@ai...>
To: <pli...@li...>
Sent: Monday, September 09, 2002 11:51 PM
Subject: Re: [Plib-users] Problem with rotations


> Ben Woodhead wrote:
> > I did read these articles but I will read them again. But I did use a
matrix
> > stack from the rotations and I am only rotating around 1 axe. If I
change
> > the code to just rotate around x it works, and if I change it to rotate
> > around just z there is no problem, but just y causes some really weird
> > results. Did you have a look at the code..
>
> Sorry - no - I've been kinda busy.  I've seen *thousands* of cases of
> objects rotating nicely around the Y axis - so I'm not inclined to suspect
> a bug in PLIB...but anything's possible.
>
> Just to be *sure*, I went into examples/src/ssg/tux/tux_example.cxx - and
> changed the line:
>
>    sgSetCoord ( & tuxpos, 0.0f,  0.0f, 0.0f, frameno, 0.0f, 0.0f ) ;
>
> ...and switched 'frameno' from Heading (Rotation about Z) to Roll
(Rotation about Y):
>
>    sgSetCoord ( & tuxpos, 0.0f,  0.0f, 0.0f, 0.0f, 0.0f, frameno ) ;
>
> ...and tux leans to the right, gradually disappears under the pedestal and
> reappears on the left...exactly as I'd expect.
>
> ----------------------------- Steve Baker -------------------------------
> Mail : <sjb...@ai...>   WorkMail: <sj...@li...>
> URLs : http://www.sjbaker.org
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