From FlightGear wiki
- Restore near/far camera using depth range instead of clear to work with Rembrandt.
Distance to viewer computation will change to cope with the two ranges.
fg_Planes uniform need to convey three planes instead of two. Maybe fg_Planes_n and fg_Planes_f will be created (note: middle plane needs different parameters for the two ranges).
- Use geometry shader and instancing to compute shadow map to a texture array. Capitalize on OGL 4 features. (Seen in the OpenGL Insights book)
- Use geometry shader and instancing to compute multiple shadow maps for additional light sources.