[vtkusers] no actor required for volume redering using vtkImagePlaneWidget?;

[Dean Inglis]

Hi Chen

 

vtkImagePlaneWidget is a kind of "composite object" that maintains a number
of actors internally:

an actor for the margins and an actor for the actual image slice.  There are
a number of similar

objects called widgets in VTK/Widgets wherein the internal actors are added
to or removed

from the renderer when the widget's SetEnabled medthod is called.  Widgets
are special because

they respond to mouse events and act on them depending on what they are
designed to do.

There are other examples of composite objects with numerous internal actors
in VTK, particularly 

in VTK/Rendering and VTK/Hybrid.  The only difference with those objects is
that they do not

respond to the mouse interaction: you can only change the camera view
interactively.  It is the

data (an image) that gets set as input to vtkImagePlaneWidget and the widget
builds an internal

rendering/interaction pipeline to display and interact with that data.  So,
it is not a common

mechanism in VTK.  See VTK/Examples/GUI for other widget examples.


Dean

 

 
My basic knowledge tells me that every renderer needs at least one
actor/object 
associated with it. However, when I used vtkImagePlaneWidget to view a 3d
volume, no 
actor/object was really added to the renderer created. I am wondering that
how the 
renderer knows which actor/object to render? The only hint I can perceive is
that 
the actor/object to be rendered is set as input to each ImagePlaneWidget and
each 
ImagePlaneWidget is associated with one RenderWindowInteractor which in turn
gets 
connected with the renderer. Is this how the renderer connected with the
actor/object?  
If yes, is this a common mechanism used in VTK (it is quite different from
the cone 
examples)? Is there any similar example available? 
 
 

Chen

 

 

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