[vtkusers] Getting box coordinates

[Sebastien Jourdain]

Hi Ayman,

I guess that you will have to do as David said.
But maybe on an assembly you can call update and ask for its bounds.
Unfortunately I didn't check what is available on vtkAssembly.

Seb

On Wed, Sep 8, 2010 at 1:51 PM, Ayman Habib <ahabib at stanford.edu> wrote:
> Hi Seb,
>
> To follow up on this trail, I assume that this call requires the geometry to
> be rendered already before you make the call (otherwise you get the
> uninitialized box of -1,1 in each direction).  Is there a way to compute
> these bounds for a vtkAssembly before it is actually rendered? I need to
> discover how big an assembly is before I add it to a scene (that already
> contains other assemblies).
>
> Thanks,
> -Ayman
>
> ----- Original Message ----- From: "Sebastien Jourdain"
> <sebastien.jourdain at kitware.com>
> To: "David Doria" <daviddoria+vtk at gmail.com>
> Cc: <vtkusers at vtk.org>
> Sent: Monday, September 06, 2010 4:49 AM
> Subject: Re: [vtkusers] Getting box coordinates
>
>
> On the vtkRenderer, you do have a method that do exactly that.
>
> void ComputeVisiblePropBounds  (double bounds[6])
> double * ComputeVisiblePropBounds ()
>
> Moreover, if you call ResetCamera() on the camera, you migh get the
> result that you try to achieve.
>
> Seb
>
> On Mon, Sep 6, 2010 at 6:38 AM, David Doria <daviddoria+vtk at gmail.com>
> wrote:
>>
>> On Mon, Sep 6, 2010 at 4:27 AM, Mario Rodriguez <biomates at telefonica.net>
>> wrote:
>>>
>>> Hello,
>>>
>>> I have a scene formed by several objects (some of them obtained from
>>> translation and/or rotations) bounded by a box (vtkAppendPolyData +
>>> vtkOutlineFilter). Then I draw the axes with the corresponding x-y-z
>>> tics (vtkCamera + vtkCubeAxesActor2D). Everything works fine.
>>>
>>> What I need is to set the camera parameters automatically from the
>>> dimensions of the bounding box. Instead of writing explicitly something
>>> as
>>>
>>> vtkCamera camera
>>> camera SetFocalPoint 2 3 3
>>> camera SetPosition 15 15 15
>>> camera SetViewUp 0 0 1
>>>
>>> I need to set the focal point to the geometric center of the box and the
>>> position coordinates at a certain distance from the scene. And the
>>> question is: is it possible to get the x-y-z ranges of the complete
>>> scene, and after some simple calculations pass the necessary values to
>>> SetFocalPoint and SetPosition?
>>>
>>> I haven't found any example solving this particular problem.
>>>
>>> Sorry if this question is very basic, but I've started to make my first
>>> steps into vtk some days ago and I am not very familiar with this
>>> software.
>>>
>>> --
>>> Mario
>>
>> This isn't particularly elegant, but you could loop over all of the
>> actors and call GetBounds
>>
>> http://www.vtk.org/doc/nightly/html/classvtkActor.html#a65b0a469a62bb01862777a47784c3dbc
>> on each of them and keep track of the min/max in all directions.
>>
>> David
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