Help with train bellow/gangway

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#1

Hello there, I’ve been working on a train system and at the moment I’m wanting to make a functional bellow (The bouncy thing thats in between 2 carriages) however I’m having some issues with it. Note: I’ve never used bones or mesh deformation before so I don’t know how I should do this.

I’ve followed these 2 tutorials:

However when I place the bones exactly how it shows in the video (Both the bones heads at center and their tails on each edge of the bellow), importing the mesh into Roblox it create the bones at the center of the mesh even though I want the bones to spawn at the ends of the gangway, so I went back into Blender and I went into edit mode and I flipped the direction of each bone which made the bone heads at the edge and tails at the center of the mesh, which fixed the problem and created the bones how I wanted in Roblox Studio, however I’m not sure if the information above has anything to do with my next problem I’m on but I’ve included it anyway.

The next problem is, when I try to pose the bones it doesn’t deform the mesh how I want, when I move a bone on one end of the mesh, it’ll only adjust the mesh on that end (which is how i want) but when I move the other bone on the other end, it’ll move both ends.


As you can see, the first bone I moved doesn’t move the vertices on the other end, which is what I want, but for both ends, but when I move the second bone on the other end, it moves the other end. I’m 99% sure the weight is the problem, and I’ve train to mess with the weights all day but couldn’t acheive what I want.

Heres a picture of the mesh at its “rest position”

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Heres a picture of the current weight set up
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Heres the blender file, if you’d like to do it for me or have a look at some things in it for example, the bone set up. If you do do it for me please be sure to let me know how and what you did to fix it!
Bellow.blend (1.0 MB)

Please help me! Any help is greatly appreciated!

Reason I need to fix this

It’ll leave a gap between the train and the bellow if i don’t fix it.

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#2

Seems like the weight for Bone.001 is good but for Bone it looks like this:

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Trying to use either Enveloped weights or Automatic weights yields undesired results.

You can instead manually use the Gradient tool in the Weight Paint mode. Hold ctrl to snap the gradient angle:

#3

Man you’re a life saver! You’re telling me I worked all day on trying to fix this problem just for a tiny adjustment?? I didn’t know you could weight paint each bone invididually I thought you do it all at once! Oh well, thats what happens when you’re still learning these things!

I’ll play around after to make sure it works properly how i want before I mark you as the solution!

2 Likes
#4

Results:

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Wouldn’t mind telling me how I can weld the bones to the attachments in the trains engines? Currently i have a script that sets the bones world position to these attachments in each carriages engine (a rigid constraint doesn’t work)

#5

Looks great!
Sadly I don’t have any ideas on how to weld bones to parts, I could only find info about welding parts to bones. I think repeatedly moving the bones to the target location is a perfectly fine way to do it in this case.

#6

Thats currently what im using but thats a bit jittery especially when the train is moving

#7

Are you using a RenderStepped() connection for it? Also if possible you could anchor the skinned mesh unless it’s already welded into the train.

#8

I’d prefer it to work without a script if possible and more like a rope constraint maybe?

#9

Quick question, what would I make the weights look like if I’d want it to kind of push into each other if i moved the bones closer? At the moment it only seems to press together at the center of the bellow

#10

Follow the earlier example but use Linear Falloff for the gradient weight painting:

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#11

Thank you! It moves and bends perfectly! I’ve learned lots from you about bones!

Now I just need to find a better way to join it to the carriages! Welding it to the train seems to improve the script but still would be better to have no scripts doing this

#12

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