Weird Land Impact problem

[Brick Swansen]

Hello,

Can someone help me understand this so that I can fix the problem please? I have a mesh building created in Blender. I've uploaded it with 4 levels and a physics model. It has 6 links total. Each link has a corresponding physics shape in the physics model. When I upload it, it comes in at 36LI. When I change the physics of all the links to "prim" it increases to 104LI! If I decrease the size of the building the LI increases!! I haven't had this happen before. Halp! ..please. Thanks.

[Brick Swansen]

Additionally, if I change the floor link to Convex Hull the LI comes back down to 47. But I really would rather use the physics model shape.

[ChinRey]

19 minutes ago, Brick Swansen said:

When I upload it, it comes in at 36LI. When I change the physics of all the links to "prim" it increases to 104LI!

That's because your physics models are too complex. Keep in mind that the physics only purposes: blocking avatars (and some objects) from passing through solid objects like walls and giving them a surface to walk on.

For a house you need vertical physics planes for the walls, horizontal ones for the floor(s), either horizontal or vertical (depending on the design of course) for the roof and possibly horizontal ones for the ceiling(s), all of them made with as few and big tris as possible. The physics for the walkable surfaces should be placed with millimeter precision for the other physics surfaces you may well get away with up to half a meter of leeway.

 

30 minutes ago, Brick Swansen said:

If I decrease the size of the building the LI increases!!

That's the physics again. HAVOK, the physics engine SL uses, doesn't like small triangles so when you reduce the size of the mesh, the physics weight may increase.

[Brick Swansen]

48 minutes ago, ChinRey said:

That's because your physics models are too complex. Keep in mind that the physics only purposes: blocking avatars (and some objects) from passing through solid objects like walls and giving them a surface to walk on.

For a house you need vertical physics planes for the walls, horizontal ones for the floor(s), either horizontal or vertical (depending on the design of course) for the roof and possibly horizontal ones for the ceiling(s), all of them made with as few and big tris as possible. The physics for the walkable surfaces should be placed with millimeter precision for the other physics surfaces you may well get away with up to half a meter of leeway.

 

That's the physics again. HAVOK, the physics engine SL uses, doesn't like small triangles so when you reduce the size of the mesh, the physics weight may increase.

Thank you! I messed around with the floor mesh and dissolved some verts. It did help a lot! There weren't even that many, but apparently enough to make HAVOK mad. Thanks very much for the response.

[Naiman Broome]

Have u tried setting the main physic shape to the root prim and leave the others to none?

[Brick Swansen]

20 hours ago, Naiman Broome said:

Have u tried setting the main physic shape to the root prim and leave the others to none?

I have not. Do you mean say having the floor as root prim, then within that prim are all of the shapes needed for the other links? I typically create a physics link for each link that needs physics.

[Chic Aeon]

You might also try uploading each section separately and then putting them together inworld. a LOT of building makers use that system :D.   And you can easily see how well your physic mesh is defining in relation to the building itself. I can't imagine seeing a whole house all at once and being able to tell what might be wrong :D.

Good luck. 

[VirtualKitten]

It might be that your physics is all in separate forms . Maybe try put them in one with blender  and use that as physics! hugs

[Brick Swansen]

On 10/8/2021 at 6:54 PM, Chic Aeon said:

You might also try uploading each section separately and then putting them together inworld. a LOT of building makers use that system :D.   And you can easily see how well your physic mesh is defining in relation to the building itself. I can't imagine seeing a whole house all at once and being able to tell what might be wrong :D.

Good luck. 

Yes, I've done it both ways and you're right... it's maddening doing all at once! lol

7 hours ago, VirtualKitten said:

It might be that your physics is all in separate forms . Maybe try put them in one with blender  and use that as physics! hugs

Thank you

[Naiman Broome]

On 10/8/2021 at 10:48 PM, Brick Swansen said:

I have not. Do you mean say having the floor as root prim, then within that prim are all of the shapes needed for the other links? I typically create a physics link for each link that needs physics.

depends on your needs but you have something simple you do not need tomake a physical shape for each linked item if they will be linked inthe end, you can just have one based on the root prim , this shape will stretch to the borders of the root prim and cover the whole prim , if you go in feature and click on the little eye when you import the itmes you can see their physical shape and if they overlie on each other, you can sure add a physical shape for each linked item if is usefull for u or save some using only one , in some cases they could be conflicting with each other.