Hi,
what's the best way to detect a top surface based on placement of an object, like for example the placing of objects in game turning blue or red.

Currently I ray trace to the surface..  & place an object,  but if i want to place another object offset from the inital object... whilst maintaining integrity with the landscape... then it is not just a case of  changing the  X & Z co-ords (obviously)

And nope.... " TerrainMeta"  is not always the top surface you want to place on, certainly not in the  "ice biome"

So..
1. Place object based on "raytrace to surface"  (working)
2. work out relevent offset from first object
3. Check  visible player surface , place/recalc

Is the best way to continually ray trace from the players perspective with an offset or use some other way?

The navi mesh seems broken currently, also full of holes or mismatches with the landscape.

like frozen lakes the navi mesh seems to be UNDER the surface...

Look at GamePhysics.cs, maybe the methods that start with 'Check' can be useful.  I use them to make sure the area is clear when I spawn vehicles.