> You can first
> raytrace one mesh and then another (using the same z-buffer method for
> surface removal as in scanline rendering).

Yes, that's true. That can be an efficient way
in some cases, like when a heightfield presents
a slim or small profile. What I particularly
like is that it provides a fine-grained way
to mix scanlining and raytracing.

One difficulty I have with doing that is that
sometimes its easier to drive a shader using
some stepped coordinate system of the primitive rather
than the world locations a raytracer returns.
For example, when scanlining a heightfield,
I do it cell by cell, so rocks can be distributed
based on how likely a cell is to be occupied.
With raytracing, I have to derive the cell
coords, and then maintain some kind of map
to keep track of which cell was painted with what.
I realize it's not good form to write primitive-specific
shaders, but they can be much easier to do sometimes,
especially when prototyping.

Displacement shading is also easier when scanlining.
At least, I haven't figured an easy way to do it
when raytracing.

Hmm.. this thread has been a good exploration
of the pros and cons of the two rendering techniques.
I'll make a digest of them and add it to my website.

Ray

Post a reply to this message