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TrackballManipulator asymptote


 
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rbp
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Joined: 23 Feb 2009
Posts: 24
Location: Melbourne, Australia

PostPosted: Wed Oct 29, 2008 3:55 am    Post subject:
TrackballManipulator asymptote
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hello,

when I use the TrackballManipulator to view my model I find that the
camera velocity slows to zero if I try to approach a certain point,
which I believe is the origin.
Do you know why this occurs and how it can be prevented?

Richard


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Robert Osfield
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PostPosted: Wed Oct 29, 2008 9:23 am    Post subject:
TrackballManipulator asymptote
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Hi Richard,

The trackball slows as you move into the origin as the rate of
movement in is always a percentage of distance from the center to the
eye point. This is just the way it works, it's not some that can be
"fixed" as it's doing exactly what it's meant to do.

Now if you want some custom manipulator that kinda behaves like the
TrackballManipulator then you'll need to subclass or just write your
own from scratch. One hack you could implement is the pushing
forward of the center as you get near to it, rather than just keep
reducing the distance between the eye and the center.

Robert.

On Wed, Oct 29, 2008 at 3:54 AM, Richard Baron Penman
<richardbp+> wrote:
Quote:
hello,

when I use the TrackballManipulator to view my model I find that the
camera velocity slows to zero if I try to approach a certain point,
which I believe is the origin.
Do you know why this occurs and how it can be prevented?

Richard




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rbp
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Joined: 23 Feb 2009
Posts: 24
Location: Melbourne, Australia

PostPosted: Thu Oct 30, 2008 11:39 pm    Post subject:
TrackballManipulator asymptote
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thanks again Robert - now I better understand how TrackballManipulator works. I overloaded the calcMovement() function to move consistently and it is working well.

Richard


Quote:
Hi Richard,

The trackball slows as you move into the origin as the rate of
movement in is always a percentage of distance from the center to the
eye point. This is just the way it works, it's not some that can be
"fixed" as it's doing exactly what it's meant to do.

Now if you want some custom manipulator that kinda behaves like the
TrackballManipulator then you'll need to subclass or just write your
own from scratch. One hack you could implement is the pushing
forward of the center as you get near to it, rather than just keep
reducing the distance between the eye and the center.
Robert.


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