Mesh: Physics shape is solid but can walk through with repeated collisions.

[Yingzi Xue]

I'm working on a mesh boat.  I've made a physics shape out of planes in Blender, and upload it with the mesh object.  The physics shape shows solid in Render Metadata, but if I collide with it repeatedly, it will allow me to walk through it, even though it's supposed to be solid.  Is there a certain thickness a physics shape has to be to keep this from happening?  Or am I missing something?

Edited March 22, 2022 by Yingzi Xue

[Rolig Loon]

It depends on how fast you are going.  If the mesh is thin enough that your center can pass through its center in one frame (1/44 sec), then you will pass right through it.  We've had trouble with arrows shooting right through targets for as long as SL has been around.  You have two choices:  Make the object thicker or move slower as you collide.

Edited March 22, 2022 by Rolig Loon

[Yingzi Xue]

Thank you for the quick response.  I'll make it thicker.

[Yingzi Xue]

I made it .2 thick and it fixed the issue.  I may experiment with slightly thinner just to see where the sweet spot is.

[Yingzi Xue]

.1 works as well.  Edit:  Although this may not be consistent either.  I recommend thicker.

Edited March 22, 2022 by Yingzi Xue

[Chic Aeon]

If you are using planes physic for you model, you could use CUBE physics instead.  If you use double sided objects for your physics model they need small spaces between them and need to be ANALYZED in the uploader.  You may already know that but others might not :D. 

I always use cube physics and have never found any issues.   

[VirtualKitten]

Sorry to jump in but have been experiancing similar physics concerns where you can walk through walls and not fall through holes. My frend Aquila could achieve it firstly he named all the physics  _PHS one for each object in blender id name  . This amazingly found the physics and looked correct in uploader. Now when in Secondlife had this object in world this didn't work one of my other friends helped me realize that this was being influenced through other physics  of a different object in world. currently we have a non ideal solution a mesh object with non physical and a prim invisible object it was the only way to resolve this at the time I don't know why there seems to be physics interrupting physics in world other than you need to move between them! I hopes this helps.

[animats]

Convex decomposition with all parts at least 0.20m thick seems to be reliable. If you're having problems, spend some time in the uploader looking at the analyzed pieces into which the uploader is breaking apart your model. The uploader tries to break the model apart into simple convex forms which add up to the original model. You can look at what it's doing, especially since Beq Janus made the window in the uploader resizable in Firestorm. Try to get a decomposition into thick rectangular solids, not pointy polygons with narrow sections.

Some builders recommend small breaks between rectangular solids, to force the convex hull decomposer into using rectangular forms. That's an option, if the decomposer is doing a bad job, which it often does.

(I've built escalators that work in SL. Those move the avatars using collision physics and friction. The geometry is simple but touchy. Getting the physics system to do the right thing reliably required close attention to the physics model. The hardest problem was getting the escalator to smoothly deposit the rider on the upper platform, instead of the rider getting stuck on the moving part, walking in place. Early attempts had extra pushers and rollers, but eventually I got it all to work with simple one-piece physics models.

Physics does really start to turn on near 0.20m. Less than that, and you can get some strange effects, like two stacked layers moving separately both influencing something standing on them.)

 

[Yingzi Xue]

Thank you all for your responses. 

• Yes, I was aware of the spacing between prims to get physics to come out correctly, and the physics shape looks perfect, even when rendering metadata for physics. 
• The physics shape was solid, until you bumped into it a few times repeatedly, and then you popped out the other side. 
• I do think .2m+ is definitely the way to go for consistent results.

I'm still trying to develop a good (simple) workflow for modeling buildings in Blender for Second Life without it becoming a convoluted mess, so I'm looking at the work of others for clues.  I was looking at one builder's work.  He seems to make all of his walls out of planes, and his physics turn out just fine.  I tested with a single plane wall and I couldn't walk through it, even though it's not .2 thickness.  I'm guessing he uploads each wall piece individually as planes then assembles them.  Another interesting thing he does is overlaps his walls by .2m on each end.

These responses have helped.  Much appreciation.

Edited March 31, 2022 by Yingzi Xue

[VirtualKitten]

Hmm .02 was to small for the thickness  of the Physics for me. It gave me errors ' your mesh is to dense' error and would not import it  until I made thickness .006 . Hope this helps.