WTF is a collision prim?

[Rhiannon108]

I bought an object (bridge) but turns out you can't walk on it. I fall through it. A reviewer said you can just make a "collision prim." What the heck is that? Is that easy or should I just look for another bridge?

[Kardargo Adamczyk]

The bridge is probably a sculpted prim and therefor set as a phantom object, just rezz and shape some prims to walk on and turn then 100% transparent after you are done... you can contact me inworld if you need some help with that..:)

Edited May 29, 2019 by Kardargo Adamczyk
typonese

[Rolig Loon]

If you are trying to bridge across a region boundary with it, the problem is the the bridge is only "real" in the region where its root is.  If you walk onto the bridge from that side, you can continue walking on it as you cross the border into the other region, because the region's server still treats you as a recent agent in the region where the bridge's root is ... no problem.  However, if you try to walk onto it from the other region, you are walking onto an object that does not exist there.  You fall through.  The usual solution is to create an invisible bridge with its root in the other region.  It doesn't have to be anything fancy.  Just create a prim that is maybe 6m long and overlap it with your "real" bridge.  Be sure that its center is on the other region.  Then turn it 100% transparent.  Voila!  A collision prim (so-called because you can collide with it and walk on it, even though you cannot collide with the visible bridge and walk on it.).

Edited May 29, 2019 by Rolig Loon

[Rhiannon108]

10 hours ago, Rolig Loon said:

If you are trying to bridge across a region boundary with it, the problem is the the bridge is only "real" in the region where its root is.  If you walk onto the bridge from that side, you can continue walking on it as you cross the border into the other region, because the region's server still treats you as a recent agent in the region where the bridge's root is ... no problem.  However, if you try to walk onto it from the other region, you are walking onto an object that does not exist there.  You fall through.  The usual solution is to create an invisible bridge with its root in the other region.  It doesn't have to be anything fancy.  Just create a prim that is maybe 6m long and overlap it with your "real" bridge.  Be sure that its center is on the other region.  Then turn it 100% transparent.  Voila!  A collision prim (so-called because you can collide with it and walk on it, even though you cannot collide with the visible bridge and walk on it.).

I own a property that is two adjoining 1024m plots. I assume since I own both it's one region, right? The bridge isn't flat. It's one of those that go up in the middle. To seem to walk naturally on the bridge, won't I have to create an invisible prim that assumes the same shape? Here's a link to the original sales page so you can see the shape...

 

https://marketplace.secondlife.com/p/DSTOPIAN-Asian-Bridge/10265077

 

[Rolig Loon]

Yeah, it sounds like all in one region, so the stuff I gave you doesn't apply, but Kardago's does.   Your collision prim does have to be fairly close to the same shape as the walking surface on the bridge, but it doesn't need to be a perfect fit.  It will be transparent anyway, so no one will know.  Just rez a cylinder prim and stretch it a bit until it's more or less right.

[Wulfie Reanimator]

Let's pretend this is a mesh bridge with a bad "collision shape" (which tells avatars what is walkable).

To fix this, all you need is to rez a prim (for this shape, a cylinder is probably the best solution), size it over the bridge and make it invisible.

And now your bridge is properly walkable.

[Coby Foden]

You need to add railing collision prims too so that drunk avatars don't accidentally fall down when walking in zig-zag fashion on the bridge.

[arabellajones]

If you're working with mesh, the collision prim can be mesh, so the bridge deck and side rails could all be one component. But if you do that you can't use that convex hull option for the collision prim/physics model. The L-shaped kitchen here can't use a convex hull. The stool would be inside the physics shape. It does use a mesh physics model, which isn't strictly a collision prim but it does the same job. It's simpler, lower physics cost, than using the detailed visual model.