Location Is Everything?

[Tad Carlucci]

OK, I'll take a guess .. your house is Mesh, right?

Add an invisible floor prim with the top just slightly above the floor of your Mesh house.

As to how to fall through .. in a nutshell, the trick is to "get inside". When you (a prim) and a box (another prim) need to occupy the same space, the physics engine marks you both temporarily phantom with respect to each other. If the box was a "floor" you (or a cat, or any "Physical Object") will begin to fall. Once you've (or whatever) have fallen (or walked, flown, whatever) so that you are no longer "inside" the engine removes the temporary phantom status.

So, how does a cat do it? Well, the cat is not always physical. If, when it's non-physical (that is, not moving about) it changes position (say, goes from sitting to laying on it's back) it's possible that part of the cat will move "inside" another prim. When, in a few moments, the cat decides to "walk" it goes physical. At that moment, the cat and the wall/floor/whatever are "inside" each other and the physics engine fixes the problem by marking them phantom. If, when the cat's done moving, it's now "outside" the wall/floor/whatever, the next time this happens, it "bumps" the wall/floor (now ceiling)/whatever and, since they're not phantom to each other this time, bounces off.