[vtkusers] Actors in front of camera clipped despite ResetCameraClippingRange()

[Elvis Stansvik]

2016-06-21 13:27 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:

> I just found this very old bug:
>
>     http://www.vtk.org/Bug/view.php?id=7823
>
> I forgot to mention that I'm using parallell projection for the camera.
> Could this be the issue I'm seeing? It seems the suggested patch there was
> never incorporated due to test failures (?). Anyone know of some way of
> working around this?
>

It seems someone else also reported the same problem in 2009:

    http://public.kitware.com/pipermail/vtkusers/2009-April/051510.html

Anyone know if this is the same old problem, or if it's something that may
have resurfaced? I'm using VTK 7.0.0.

Elvis


>
> Elvis
>
> 2016-06-21 13:06 GMT+02:00 Elvis Stansvik <elvis.stansvik at orexplore.com>:
>
>> Hi all,
>>
>> I have a setup where the camera always moves on a cylinder of radius 3.0
>> around my subject (just testing with a stack of cones at the moment). The
>> focal point is always positioned along the Y axis, and the camera may be
>> moved up and down independent of the focus point, but the camera is always
>> at a distance of 3 from the Y axis.
>>
>> As soon as the user moves the camera, I reset the camera clipping range
>> with ResetCameraClippingRange(). Despite this, when the camera and the
>> focal point are far away from eachother, the actors (my stack of cones) get
>> clipped by the near plane for some reason.
>>
>> See the attached screenshot which shows the clipping.
>>
>> What I'm doing to my camera (in response to Shift+mouse drag in my custom
>> interactor) to end up in this situation is just:
>>
>>         camera = renderer.GetActiveCamera()
>>         (x, y, z) = camera.GetPosition()
>>         camera.SetPosition(x, y - self.PanningFactor * dy, z)
>>         renderer.ResetCameraClippingRange()
>>
>> and I've verified that the camera is always at a distance of 3.0 from the
>> Y axis.
>>
>> The cones I'm using in this test were created with:
>>
>>     for i in range(-10, 20):
>>         coneSource = vtkConeSource()
>>         coneSource.SetDirection(0, 1, 0)
>>         coneSource.SetResolution(8)
>>         coneSource.SetCenter(0, i, 0)
>>
>>         coneMapper = vtkPolyDataMapper()
>>         coneMapper.SetInputConnection(coneSource.GetOutputPort())
>>
>>         coneActor = vtkActor()
>>         coneActor.SetMapper(coneMapper)
>>
>>         widget.renderer.AddActor(coneActor)
>>
>> I don't understand why I see clipping occur here, since I'm using
>> ResetCameraClippingRange, and nothing is behind the camera. The radius of
>> these cones is the default (0.5).
>>
>> It's probably something stupid, but any advice is much appreciated.
>>
>> Elvis
>>
>
>
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