[vtk-developers] Major problem in vtkRenderer.h

[Lisa Avila]

Hello Chris,

Yes - in this case since vtkRenderer is so large already, there typically 
aren't too many of them in an application, and the first method requires 5 
extra computations of the bounds, the addition of 24 bytes to the class 
size is not important. In general though I think we should avoid adding 
ivars to classes with the sole purpose of passing back some information 
through the Tcl wrapper.

Lisa



At 10:45 AM 9/10/2002, Volpe, Christopher R (Research) wrote:
>Sorry about the mac bug. You're right, Lisa, I should have avoided the use 
>of the static variable,
>particularly for thread safety reasons. I think Andy's solution is 
>probably best. The solution below
>requires that the ComputeVisiblePropBound method be called six times in 
>order to get all six boundary
>values. The extra class storage for a renderer ivar would be negligible 
>(how many renderers does a
>typical application instantiate anyway, compared to, say, the number of 
>Prop3D's that get created,
>which already have this variable.
>
>I'll check in a new version shortly...
>
> > Hello,
> >
> > Even if this could work on the Mac it should not be in VTK.
> > Since we can't
> > change the fact that VTK returns pointers to arrays (although
> > getting rid
> > of that would be great!) one solution is to add a method
> > something like this:
> >
> > float GetVisibilePropBound( int index )
> > {
> >    float bounds[6];
> >    this->ComputeVisiblePropBounds(bounds);
> >
> >    if ( index >= 0 && index <6 )
> >      {
> >      return bounds[index];
> >      }
> >    else
> >      {
> >      vtkErrorMacro("Bad index: " << index << " . Should be 0 to 5" );
> >      return 0.0;
> >      }
> > }
> >
> > This method does not require any additional class storage,
> > and is safe
> > across multiple instances of a vtkRenderer even when running
> > simultaneously
> > in different threads. Probably the next best solution would
> > be the one Andy
> > suggested - create an ivar to store the returned value.
> > static variable
> > should be avoided at all costs.
> >
> > Lisa
> >
> >
> > At 09:47 AM 9/10/2002, Andy Cedilnik wrote:
> > >Hello,
> > >
> > >Last night somebody added this to vtkRenderer.h. We need to
> > get rid of
> > >this, since it does not work on Mac:
> > >
> > >   // Description:
> > >   // Wrapper-friendly version of ComputeVisiblePropBounds
> > >   float *ComputeVisiblePropBounds()
> > >     {
> > >     static float bounds[6];
> > >     this->ComputeVisiblePropBounds(bounds);
> > >     return bounds;};
> > >
> > >If there is another way, please use it. For example, create a member
> > >variable, and then do this:
> > >
> > >   float *ComputeVisiblePropBounds()
> > >     {
> > >     this->ComputeVisiblePropBounds(this->ComputedVisibleBounds);
> > >     return this->ComputedVisibleBounds;};
> > >
> > >                         Andy
> > >
> > >
> > >
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