[vtkusers] matrix rotation "jumps"

[tom fogal]

I hate when I forget to CC the list...
------- Forwarded Message

From: tom fogal <tfogal at apollo.sr.unh.edu>
To: Christopher.Moore at noaa.gov
Subject: Re: [vtkusers] matrix rotation "jumps" 
In-Reply-To: Your message of "Mon, 25 Oct 2004 17:43:47 PDT."
             <Pine.LNX.4.44.0410251736470.23129-100000 at kingfisher.pmel.noaa.gov> 
References: <Pine.LNX.4.44.0410251736470.23129-100000 at kingfisher.pmel.noaa.gov> 
Date: Mon, 25 Oct 2004 21:12:02 -0400
Sender: tfogal at apollo

 <Pine.LNX.4.44.0410251736470.23129-100000 at kingfisher.pmel.noaa.gov>Christopher
.Moore at noaa.gov writes:
>
>I'm using the GetTransformedPosition() method in vtkLight to simply rotate 
>a light's position around the origin (as the sun would rotate around the 
>earth).
>
>I set up a vtkMatrix4x4 with the proper elements to rotate around the z 
>axis, and use a callback to repeatedly call:

It seems weird to me that you would have to do this. I have yet to try
anything of the sort (in VTK), but intuitively i'd believe that the
underlying graphics library should do this for you and you should only
have to tell it what angle/axes to rotate around. *shrug* I could be
wrong.

Anyway this all boils down to: have you looked for possibly solving
this without explicitly specifying the 4x4 matrix? I would hope that
the 'internal' method (assuming it exists) would "just work".

HTH, and good luck,

- -tom

<snip>

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