Hi MasterJ, It's late now and I'll answer shortly now and write a proper answer tomorrow... I tried to integrate Hydrax to Naali previously but it turned out to be a bit more non-trivial task than I expected. What kind of programming experience you have? The Caelum development is not active anymore AFAIK, and I have been thinking about giving a shot for SkyX, a sky "plugin" made by the same guy who made Hydrax, as a replacement for Caelum in the near future. These two should work together great without making any modifications to the source codes. You can find threads for these plugins from OGRE forums, I'll link them tomorrow.
Grey skies, Ali -- http://groups.google.com/group/realxtend http://www.realxtend.org
