Re: [PyOpenGL-Users] volume rendering

[Andrew W. <and...@al...>]

Hey Dirk

There was a paper a few years ago that did this for shadow mapping, but I
> can't find it right now. The main idea is to think of the pixel/voxel as a
> cube that is split into two parts, one inside, one outside (in your case, of
> the ROI). When you render a pixel that belongs to the cube, you figure out
> where it is in the cube (fractional texcoords should be fine), and use that
> to decide whether it's in or out, and act accordingly. So for you you could
> save a plane equation that says for example that the area left of the x=.75
> point in your cube is inside the ROI, the rest is outside, and you would get
> super-voxel resolution ROIs. You could also go beyond planes to higher-order
>

Got it, sounds a lot like generating an isosurface using marching cubes or
something similar.



> I guess the question is how often you need to update the ROI, and how high
> the ROI resolution really needs to be.
>

You've hit the nail on the head, I like the idea of using shaders as it
won't require much editing of existing opengl code and would provide the
best looking results.
  Thanks for the help, much appreciated.
  Andrew