[vtkusers] Clipping planes

[James C. Robinson]

John,

I still haven't resolved the clipping plane problem. If I turn off the auto
adjust clipping plane and try to do it myself it is clunky during rotation,
zooming etc. The problem is that the near clipping plane is being set to be
a minimum of 10% of the far clipping value. This seems like a strange
approach in that it must result in the problem that I am having for a lot of
situations. It strikes me that the easiest way to resolve this would be that
the object would have a protected float minClippingNearPlaneFactor that
would be 10% by default, but that could be adjusted via a public method.
This value would then be used in ResetClippingRange. It would allow people
in my situation to override the default but result in no flickering etc.

Related to this is the fact that the zoom speed (and pan speed) seem to be
affected by a similar factor. As I zoom in closer, the dolly speed slows
down dramatically (as does the pan speed). If I remove all props, save one
that is the size of the volume to which I want to zoom and then ResetCamera,
then the zoom (and pan) speed are increased and the view manipulation is
improved. Is there any flag, value that controls this?

Regards,

Jim

______________________

James C. Robinson, PhD,
Chartered Engineer,
Kepler Engineering Software Ltd.,
42 Rivergrove,
Glanmire, Co. Cork,
Eire

Tel:         +353-21-4822028
Tel:         +353-87-2393010
Fax:        +353-21-4822721
E-mail:     j.robinson at kepler.ie
______________________

 -----Original Message-----
From: 	John Biddiscombe [mailto:jbiddiscombe at skippingmouse.co.uk]
Sent:	04 November 2002 14:34
To:	j.robinson at kepler.ie; Vtkusers at Public. Kitware. Com
Subject:	Re: [vtkusers] Clipping planes

Have a look at (eg) InteractorStyleTrackballCamera and you'll see

  if (this->AutoAdjustCameraClippingRange)
    {
    this->CurrentRenderer->ResetCameraClippingRange();
    }

after each movement you make. This continually resets the clippping planes
to be "a good fit". In your case the bounds of the dataset probably overlap
the front view plane or something and so a default min distance is used.
Turn off the auto adjust in the interactorstyle and manage your own clipping
ranges and see if it gets better.

JB


----- Original Message -----
From: "James C. Robinson" <j.robinson at kepler.ie>
To: "Vtkusers at Public. Kitware. Com" <vtkusers at public.kitware.com>
Sent: Monday, November 04, 2002 1:28 PM
Subject: [vtkusers] Clipping planes


> Dear All,
>
> I have written an application to view finite element results. The mesh can
> be of the order of 2000m in width/depth but may be only 10-30m thick. It
> also may have an important feature with a dimension of the order of less
> than 1m to view. My problem is that when I zoom in (using a vtkCamera) the
> near clipping plane is too far from the camera and part of the mesh is cut
> (clipped) away. I have tried resetting both the near & far values (using
> SetClippingRange & SetThickness) but to no avail.
>
> I have noticed that, if I set the majority of the mesh to be invisible,
but
> leave an object of the small dimension required, the zooming works fine. I
> can then set the overall mesh to be visible and the image looks fine.
> However, as soon as I move the camera position, a lot of the mesh is again
> clipped away. What is happening is that the clipping range is set to
values
> (automatically) that are suitable to zoom in on the small object when it
is
> on its own, but are reset to unsuitable values a soon as the whole
(larger)
> object (mesh) is visible.
>
> Has anybody any suggestion?
>
> Regards,
>
> Jim
> ______________________
>
> James C. Robinson, PhD,
> Chartered Engineer,
> Kepler Engineering Software Ltd.,
> 42 Rivergrove,
> Glanmire, Co. Cork,
> Eire
>
> Tel:         +353-21-4822028
> Tel:         +353-87-2393010
> Fax:        +353-21-4822721
> E-mail:     j.robinson at kepler.ie
> ______________________
>
>
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