Building physics

[Flightless]

Hey guys. Let's  say i wanted to make a physics shape for a large building I made. The building has a few walls, but the walls are not linked; meaning, they are seperate objects that can be unlinked once uploaded. Do I upload a physics shape for each individual wall, or one large physics file that is in the shape of each wall, as if it were linked together? I hope this made sense. Haha. It's a bit difficult to explain

 

 

 

[Dora Gustafson]

If you want to go inside the building you don't want all the walls in one physics
That is if the physics is convex. In your example it would become a convex box
If you make the physics follow the form in the left figure it will cost in LI especially if your building is big

So the best solution in my opinion is to let each wall define the physics for it as each wall is a simple box

:smileysurprised::smileyvery-happy:

[Drongle McMahon]

If you upload a single dae file with multiple objects, then you can either accept the default phyics shapes (for each object that will be the convex hull of the low LOD visual mesh), or you must specify a physics shape for each one. If they are simple flat walls, that's easy - any smple box will do. Otherwise, you have to make sure the physics shapes are in the same order in the dae file as are the high LOD meshes. Each gets stretched and/or squashed to fit the bounding box of the corresponding high LOD mesh, and the correspondence just depends on the order in the two files. So you can get strange results if the wrong physics mesh gets associated with the wrong visible mesh, which happens if the order is different.

There is an alternative approach that lets you use a single physics mesh for the whole thing. To do that, you upload the physics shape separately and link it to the rest of the meshes with the physics mesh as the root. The you set the physics shape type of the physics mesh to "Prim" and all the others to "None", and make the physics mesh invisible. You will have to learn how to make low-weight physics shapes work for convex structures, and as mentioned by Dora, the download weight of the physics mesh may be large and will be added to the overall structure. Generally I don't recommend this approach.