Hi Nihil!
About your first question 3d actors on 2d backgrounds, it's complicated to explain, but yes this is the idea..
And the second question I don't think so at all, and i try to explain them.. I can see how work Sceneeditor with 3d geometry, and 2d areas about one month and.. well, 3d actor work with 3d geometry right and also interact with 2d areas. If an area have a script attach and for example delimit one position I can block 3d actor.. I include image and same simple code to explain best..
while(true)
{
if (actor.X < 100)
{
actor.X = 100;
}
Sleep(10);
}
when actor theoretical across 100 line delimited script, then the code return de actor.X to 100.. And we are blocked actor without z-coordinate of geometry, only need 3d actor position.. Of course only one camera have attach to 3d Geometry..
I think Mnemonic can do something like that, with Scene editor to block walls more easy than remake background in 3d..
Thanks again, and sorry my bad English!