Collision Meshes (no doubt AGAIN)

[AlphaAsh]

Argh! Seriously running out of hair. Starting to drool a little and dream of meshes. Meshes that don't work and result in crazy crazy stuff from KSP's physics.

What's the secret here? I'm missing something fundamental.

- I get that a collision mesh has to be convex. How the hell is that even possible? I'm making buildings. I need ramps and bezels/bevels(?). How exactly do I avoid concavity?

- I'm currently using multiple meshes applied in Unity to a model. Obviously, when using convex, this will result in some crazy meshes that don't fit a particular part of the model. Because there's concavity. How the hell do you have a ramp or a bezel/bevel without it? I've tried splitting faces, I've tried this, I've tried that. And the other. I'm drooling again.

- I keep seeing "use a single mesh for collision set to convex" or some such. Wait what really? But I have concavity in my model.

Any help/guidance/links on this crazy collision mesh insanity welcome.

[Justin Kerbice]

You forgot one gigantic point: buildings ARE NOT parts !

I don't use convex collider with all of buildings I've made*, no issue from now, they behave exactly like stock buildings and terrain.

Look at my stunt ring, no convex collider, plane or anything can go through it, but crash on the "walls".

If you really want convex collider: split split split and split ! But it will become a nightmare very fast (I split my first new robottom version into 18 convex colliders, FPS was already killed in VAB !)

*except the WIP CFA runway, but perhaps not in the lastest released version

Edited June 20, 2014 by Justin Kerbice
add CFA note

[AlphaAsh]

Yeah, I noted that you have some rampage in your runway which works just fine. Am I right in assuming you used a single non-convex collider on that? Or does it have multiple colliders?

[Justin Kerbice]

I build one single object as complicated as I can imagine/made, drop it into unity, ask it to add collider, don't check "convex" and export.

(I guess static thing make it more unity-friendly than parts, fortunately.)

[nli2work]

use primitive colliders for building, stairs, etc. Convex mesh colliders are for complex shaped meshes that require physics interaction with other mesh colliders. non-convex mesh colliders will work fine with other primitive colliders.

Edited June 20, 2014 by nli2work

[AlphaAsh]

I build one single object as complicated as I can imagine/made, drop it into unity, ask it to add collider, don't check "convex" and export.

(I guess static thing make it more unity-friendly than parts, fortunately.)

So a single material on a single mesh. I'm not having problems with basic models like that either.

[AlphaAsh]

use primitive colliders for building, stairs, etc. Convex mesh colliders are for complex shaped meshes that require physics interaction with other mesh colliders. non-convex mesh colliders will work fine with other primitive colliders.

I'm actually dealing with fairly complex meshes even though I'm just making buildings, so unfortunately primitive colliders aren't all that useful

[nli2work]

yeah Justin is right, if your vessel has convex collider then the building doesn't require convex collider. Only 1 of the 2 colliding mesh colliders has to be convex. you can just model your building and apply mesh collider and use the building mesh as your collider mesh.

Edited June 20, 2014 by nli2work

[AlphaAsh]

Some improvement on the latest test. As you guys suggested, I went with a second mesh with a single material as one collider on the model. It is behaving waaay better although there are still physics issues where a vessel comes in to contact with a 'concave' part of the building, such as where a sloped verge meets a wall.