[vtkusers] Show/hide actors efficiently

Tue Sep 7 09:32:24 EDT 2010

Hi,

This is just a suggestion that I haven't implemented it before with VTK.

You may build a bidirectional list sorted by the distance from the plane.

If you utilize insertion sort algorithm and binary search tree based on the
sorted list, the computation will not be that heavy when you move the plane
or  an object.

You should be able to search the plane's position at most in 10 operations
with binary search tree when you use 1,000 actors.

Good luck.

Sam.

From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf
Of Nicolas Rannou
Sent: Wednesday, September 01, 2010 6:20 PM
To: Bertrand de Boisdeffre
Cc: vtkusers at vtk.org
Subject: Re: [vtkusers] Show/hide actors efficiently

Thanks I will dig a little bit into that and let you know how it works.

It could be a solution but I guess that the next question is:

How do you update each assembly efficiently when you move the plane/box..?

Let's say that while moving the plane/box an actor moves from in front of
the plane to behind the plane. (hide->show)

How would you just move this single actor from an assembly to the other
without going through the whole assemblies?

How long does it take to show/hide an assembly of 1000 actors?

I couldn't find any solution yet to only update the visibility of the actors
that the "state" is changing.

Thanks

    Nicolas

On Sep 1, 2010, at 4:29 PM, Bertrand de Boisdeffre wrote:

If you know at the beginning where actors are positionned ( behind or in
front of plane ) , so you can divide your actors in 2 assemblies. In this
case, look at this class : "vtkAssembly". This class allows to change
properties for all actors belonging to the assembly.
If you try to check if the actor is behind/front of a plane and then change
the properties, I don't have solution.

2010/8/31 Nicolas Rannou <nicolas_rannou at hms.harvard.edu>

Hi all,

I would like to show/hide actors which are:
 - behind or in front of a plane widget
 - inside or outside a box widget
and to be able to interact with the widgets in real time to modify the
visibility of the actors.

My main issue is that I am working with thousands of actors and checking the
bounding box of each actor appears not to be efficient enough...

Would somebody know a good way to deal with high number of actors?

Thanks,

   Nicolas
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Bertrand de Boisdeffre
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