[vtkusers] Changing the direction of Z

[jimcp at cox.net]

Paul,

I have no doubt we have a shared knowledge gap, and most of it is probably on my side. and to be sure I do not have a comprehensive understanding of vtk. 

When we started on this, you had a problem with "missing or dark triangles in some models", and a problem with inverting models that resulted in dark polygon displays. You provided an illustrative example with two generated cones. One of which displays black triangles when any one axis is reversed using an actor defined transform. this was assumed to be a simulation of the right handed vs left handed model problem and was addressed by applying the transform to the polydata instead of the actor. That was to address the problem I thought we were addressing was where "some of my models are right handed and some are left handed". in that case, My opinion is you need to deal with that difference by individual model at the polydata level. Unless you disagree, I think we have arrived at a resonably conclusion in this issue. 

Now focus has moved to the yet to be demonstrated problem of "Some of my models normals are inverted". I am not an expert in this area, but I think that class of problem would be addressed in vtk by reducing the contour to it's component points, and then generate a new polygon mesh with newly computed normals. If you have a readable file you would like to post as an example of this issue, I don't mind having a look. 

finally we have a problem "I need to display a mirrored world view". I am imagining a display mounted in a kiosk with a mirror reflecting the image. I will have to defer to other readers, I agree this might be a camera or renderer function. I hope they are still reading.... 

Hope that helps, 
Jim
I understand each of these is a problem that probably involves a transform, but I see them as three separate problems. 
---- Paul Harris <harris.pc at gmail.com> wrote: 
> On 26 October 2010 20:06, Paul Harris <harris.pc at gmail.com> wrote:
> 
> >
> >
> > I still believe there is a disconnect between what I understand, and what
> > you understand.  At the risk of p***ing you off, I'll try and put my case
> > again..
> >
> 
> sorry I meant, "at the risk of annoying you with this ongoing discussion
> ..."