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A Very Basic Question


Phil Deakins
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Considering that mesh ha been around for some time now, I ought to know the answer to this but, never having got into mesh, I don't. So....

Take a 1-prim, 4-legged, sculptie table and turn it upside down so that its legs point upwards. Because of its bounding box, nobody can simply walk between the legs. My question is, if it were a 1 prim mesh table, would the same bounding box problem apply, or could anyone walk between the legs?

Sorry it's such a basic question, but I don't know the answer and i would like to know it.

Thank you :)

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(not done any mesh for a while (like a year or two))

But, i assume it would depend how the pysical type (convex hull, prim etc) was setup and if custom psyical mesh was made.

But, it is do able.I don't know how hard it would be to keep the 1prim limit, as the prim weighting has all changed. but i think should be able to pretty easy. (was from what i remember a few year or so ago though).

With mesh you can build your own psyical shapes etc. so dont have to be constrained by bounding box, but, they cost more LI weight, so more prims.

 

 

 

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The bounding box will depend on the physics model (or lack there of) of the mesh.

 

If a designer used a "cube" as the physics model then there would be no "air" between the legs; the bounding box would be the top of the table down to the ground directly underneath the table top.

If a designer used a specially made physics model that "wrapped around" the legs and table top then it would act like a real life table. (It is a bit more complicated than this but that's the general answer)

If a designer let the uploader "make" the physics model it would depend on which setting they chose. Many designers tend to just upload all furniture on lowest (not me :D) so in that case it "might" act a bit odd like it is partially phantom. I am guessing you may have run into that.

 

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So it's not just as straight forward an answer as I'd thought. It does answer one thing for me though - it depends on how it is made and/or uploaded, so an avatar may or may not be able to walk through the legs. With sculpties there is no maybe about it. With mesh it's maybe yes and maybe no :)

Thank you both for your replies.

Chic. I haven't run into the problem, so your guess was wrong :) I've never tried to make a mesh anything. I was just curious if mesh bounding boxes presented the same problem that those of sculpties do.

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Your question made me curious. So i gave it a try and made a very quick model of a table with its own physics shape. The table on the image behaves as a table normally behaves :matte-motes-nerdy:



 

  • You can stand on it
  • The feets can not be traversed
  • If you scale it up you can walk under it:



Now for the more complicated part:

 

  • If you are lazy and just reuse the table mesh as the physics mesh (which is no work at all) then you end up with a perfect "table physic" but the LI goes up to ~5.
  • If you are a bit smarter then you can put some work into optimizing your table's physics mesh. Then the physic might no longer be "perfect" but you can get it good enough for all practical purposes.

The tables in the pictures above behave correct in almost all cases and they have LI=1 even when you oversize them as in the lower image.

For the experts: the trick is to NOT create volumes but only use simple faces. The physics mesh in my example looks like this:



I hope this of any help?

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