[osg-users] Idea about shadows

[Werner Modenbach]

Hi all,

today I come over with an idea about avoiding an additional render pass 
for creating shadows.
I highly appreciate any comments and maybe hints before I start with a 
trial implementation.

I use deferred shading and my scene gets rendered in a prerender pass in 
order to get
i.e. a depth map for various effects like ambient occlusion.
I'd also like calculating shadows. The usual approach is adding an 
additional render pass
with a camera located at the light position. This gives the depth 
texture from the light point.

In the final shading pass, done from the final camera position,  I need 
a matrix for calculating
the actual positions depth from light point and compare it with the 
shadow maps depth.

So I think I could do some comparable calculation in my prerender pass 
and create a shadow map
manually without having the shadowmap prerender pass even when the 
actual camera position
isn't at light position. This would be a very welcome speedup.

Maybe I'm misleaded. So please kindly comment.

Thank you