[vtk-developers] revision of rendering process

[Lisa S. Avila]

Hello John,


>this sounds like a very sensible proposal.  Making Mappers
>exclusively responsible for drawing is conceptually much
>easier to understand for new users and people who wish to
>plug in to the vtk rendering pipeline.

I agree.

>How do you think this will address John Tourtellott's
>issues?

It will not address the general performance issues.

>I also wonder if you cannot still deal with reflection by
>having an offscreen rendering pipeline gen an
>image/texturemap that is fed into the on-screen rendering
>pipeline?  But I agree with your reasoning that the features
>you lose are not very compelling ones for your typical VTK
>user.

There are tricks that can be played for generating shadows / reflections 
for opaque scenes, and yes, we can still add these if we want. What I was 
referring to are secondary rays that are cast during the ray traversal (I 
am somewhere in the middle of my volume and I need to cast a shadow ray) 
This is easiest to do if the renderer owns the ray casting since you simply 
ask the renderer to cast the ray and return a value. It is still possible 
to do with the current modifications, but a bit harder as the API for it 
will be disappearing (it wasn't ever completely there anyway). I am not 
going to keep it in mind because I do not feel it is a feature people need 
for visualization. "fake" shadows / reflections can be quite useful 
(projecting the scene out onto a wall of a bounding box for example) and 
would be my choice for a feature to support rather than true photorealistic 
effects.

Lisa