[Opensim-dev] Negative z values

[Ai Austin]

I was just testing this on the Marineville region on OSGrid which is 
almost entirely an underwater build with the water surface set at 
40m.  The tools to translate this up and down seem to work really 
well... all I did was

a) Backup the data base and create an OAR!!!

b) terrain lower 20

c) translate scene 0 0 -20
     Except that it gave no feedback that it was operating or had completed
     and when I did a region "backup" or "shutdown" it was clear that the
     persisting of the changes was taking a long time.  So wait for that.
     600 objects translated took around 25 minutes or so to persist.

d) set region water level to default 20m

And all LOOKS great with visible terrain down to -20m below my avatar.

BUT... with the default physics engine of Bulletsim, the avatar 
cannot go down below 2m.  Changing to ODE I was able to descend to 
the new negative value sea floor and the avatar showed a position (in 
Firestorm 4.6.1) of -18m.  We ought to establish if BulletSim will 
remove that restriction so we know how to proceed in establishing 
deep water regions?

I note that there is a transition in the lighting when the avatar 
moves from just above 0m to just below.. the water gets murkier below 
0m as JustinCC mentioned.  The transition is quite sudden though.. 
but the "underwater gloom" effect is not bad anyway.

I should add that objects can be placed below 0m in Firestorm 4.6.1, 
BUT if you edit them via the tool X,Y,Z facility they zap to 0m. We 
may need to chat about that to the viewer developers if we want 
negative building to be easy.  You can though MOVE an object up and 
down in Firestorm 4.6.1.