Are sky-domes, simply textured hemispheres, does the domes mesh need to be optimized for LOD?

I think all you need can be found here: http://www.flipcode.com/tutorials/tut_skydomes.shtml

About the dome having to be LODed, I don''t think that''ll be neccesary, because you would still have about zero distance change to it (if it''s an ordinary Quake/Unreal/Half-life kinda game)

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Daniel Netz, Sentinel Design
"I'm not stupid, I'm from Sweden" - Unknown