What does it mean that a collision mesh must be convex?

[dominique120]

For instance would it be possible to make a detailed collision mesh for a bucket(cross section U)?

[Dispatcher]

This might help:

http://en.wikipedia.org/wiki/Convex_and_concave_polygons#Convex_polygons

Consider it in light of the cross section you are referring to.

[dominique120]

That cleared it up.

I guess I will have to re think my model and its components to meet this requirement.

Thanks

[dominique120]

So if U shape is an invalid shape for a collision mesh how is the Mk3 cargo bay made?

http://wiki.kerbalspaceprogram.com/wiki/Mk3_Cargo_Bay_CRG-25

Also, can the collision mesh be animated?

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So I opened up this file in blender with the mu importer and found that there is a multipart collision mesh.

I see object names like: COLBottom, COLWalls, etc.

[Starwaster]

Multiple convex meshes can be used to approximate concave meshes. It's more efficient than a concave mesh.

Which leads back to the original question. Concave collision meshes are possible. It's not like there's a hard and fast rule preventing it. It's inefficient and can lead to unwanted collision issues. I've also read but not confirmed that collisions between two concave meshes can't be handled. At all.

[smjjames]

Multiple convex meshes can be used to approximate concave meshes. It's more efficient than a concave mesh.

Which leads back to the original question. Concave collision meshes are possible. It's not like there's a hard and fast rule preventing it. It's inefficient and can lead to unwanted collision issues. I've also read but not confirmed that collisions between two concave meshes can't be handled. At all.

I guess it's because when two concave meshes collide, the engine gets confused because it's just the edge of the mesh colliding rather than the center?

I know nothing about the mesh stuff and am just guessing.

[dominique120]

So I can create a convex mesh but it would create problems?

I sort of like how SQUAD did the collision mesh for the part I saw. I will try to recreate it.

[Van Disaster]

For the cargo bay you can just use a bunch of box colliders for the walls, which unfortunately doesn't directly help for a round bucket although I suspect that'd probably be the way to go anyway - would be nice if there was an option to generate multiple box colliders instead of a mesh collider.

Learning from mistakes I've made, concave meshes appear to fall through terrain ( which is not going to be a convex collider! ).

[sumghai]

In my FusTek Station Parts, I use a series of wedge-shaped convex colliders to form rings that allow Kerbals on EVA to fly through them.

In short, for hollow or concave shapes, use multiple box or mesh colliders.

[dominique120]

I'm going to try to make a collision mesh out of a bunch of parts and see how it goes.

Thank you for the advice.