"Pre-processing" stages and shadow post-processing

[Choca13]

I could be interested by having something similar to deferred or composite programs, but running right before gbuffers programs (should not be too complicated imo).

Also, but more complicated, being able to do "post-processing" on shadow data could have a lot of uses:

• Creating a lower resolution voxel grid could allow for hierarchical raymarching and a huge performance improvement for voxel ray tracing.
• The ability to have access to fixed-size textures to do non-shadow things (volumetric rendering with froxels, storing temporal data or LUTs...) that may not work well depending on the user's render resolution.
• Could be used to speed up some shadow-related things (reflective shadow maps, exponential shadow maps...)

However a few things should be added with this:

• In order to not waste performance, adding an option to not render shadowcolor buffers during the shadow rendering pass, even if the uniform is declared after (but will be used for non-shadow stuff). This will guarantee backward compatibility.
• The ability to change shadowcolor buffers' format.

[sp614x]

What do you mean with shadow "post-processing"? Fixed-size textures currently work only read-only. Writing is always done with the framebuffer size. Writing to fixed size textures probably needs Image Load Store: #791. Configurable shadow buffer formats: #1712, #944.

[DethRaid]

What preprocessing would you want to do?

[Choca13]

By "shadow post-processing" I mean doing post-processing on the shadow data (or something else) and outputing to the shadowcolor buffers. Pre-processing stages would be mostly for me, as I want to render my sky and clouds at half or quarter resolution while using forward shading (which I use on my low-end shaderpacks). Currently, doing this would complexify the rendering too much and slow things down.

[sp614x]

Do you mean the post-shadow composites to run from the shadowlight viewpoint and the next pre-gbuffers composites to run from the player viewpoint?

[Choca13]

pre-gbuffers composite have to run at render resolution, and shadow composites have to render at shadow map resolution. Just drawing a quad.

[rre36]

+1