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bnine

Rigging a strap / chain

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Hey guys, I have a question regarding a watch strap I've made. I've seen loads of tutorials on yt on how to rig a chain the best possible way (usually with a cloner), but I can't figure out the best practice on how to rig a strap/chain when the strap "links" are not all the same shape. I've attached a couple of images below:

f2.thumb.PNG.44c232e24c312c57121514c62967a2f1.PNGf1.thumb.PNG.b88d57e4bf83a74174e1bca16b69157b.PNG

As you can see the strap starts of wide and gets more narrow down the line. After the first 5 links it's uniform, meaning every link is the same size. As far as I know a cloner object would not be suitable for this as it's not just one single object I want to object duplicate. I want to animated this with some dynamic, gravity, make it flap and so on and I'm a bit stuck. The white mesh on the left image are from a cloner object I used to get the screenshots for this post. I am still a beginner in C4D. 

Does anyone have any tips? Let me know if there are any question or if anything I wrote was unclear. 

Thank you

Ben

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If that was me, things I'd try first include dumping that whole strap into a Connect object (weld off), then spline wrapping it along... you guessed it, a spline. But then you could use Spline Dynamics on that spline to get your waving about and whatnot... you might have to do stuff to avoid twisting, but I have seen this work on similar arrangements...

 

CBR

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Quick test based on @Cerbera's idea.  Some issues to sort out, but a start at least.  Just replace my cloner with your customized geometry under the Connect.

Watch Band Chain Spline Dynamics.c4d

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Good one Nate :) Here I tweaked drag up to 10% which seems to fix most of the poly flip issues...

 

1209612012_SDdrape.thumb.gif.7b9fd24cd3494f9e3d5edbabfb77096a.gif

 

CBR

 

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  • Thanks for the super fast feedback guys! I downloaded the project and the result you got was really nice! I tried putting my strap in the connect object but I got really weird result (for some reason it scaled my object down along one axis, the mesh turned really blobby instead of hard collision like steel would interact with each other). 

    I tried recreating your setup from the ground up but I only got so far, I could not figure out how to anchor the first vertex to hold everything - but copying your spline fixed that for me (but the mess turned really blobby). 

     

    I really want to learn how to best setup an object like the one I've got. Right now I have a mixture of symmetry objects, individual objects and cloner objects. I assume that this would cause all sorts of problem if I put all of that in a Connect object (I'm not quite sure what a connect object is but from what I could read online is that children of a Connect object sort of ... connects object and act as one?)

    I've attached just the strap from my model, If you guys would not mind could you have a look at tell me if I should re-structure it? Would it just be better to have individual objects instead of the mess I currently got? 

    WatchStrap_HowCouldThisBeSetupBetter.c4d

    Thank you guys

    Ben

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    I don't have access to Cinema right now, but I know why your geo is getting whacked out. I made my cloner out of planes, then nested the whole thing in a Cloth with thickness. This is because the Spline Wrap was scewing the geo on the Y axis if I used cubes. Try first disabling the Cloth to see how it looks. You'll also need to switch the axis that the SW is using until it looks right.  Make sure your spline is also the same length as your strap object. To get it to pin one point, there's a button in the Spline Dynamics tag that says "Set vertex" or something like that. Select the point you want on your spline and click it.

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    The Connect object does work as you surmised - you can dump any group of old whatnot under it, and other systems in Cinema will treat them as a single connected entity. But that is not to say your geo couldn't be slightly more suited to purpose, or that this is the best way of doing that as we first may have thought...

     

    I've almost got it working on your file, but am also watching NAB so keep getting distracted :) I'll get it eventually if Captain Nate doesn't beat me to it.

     

    The issue I am trying to circumvent is where you have extra edges in your strap that need to be there because they define curvature, yet we have to stop those bending on the spline - they must remain solid as they follow the path, if you see what I mean, otherwise it'll just look wrong...

     

    This is surprisingly difficult to do with overlapping objects ! I think the mesh deformer in conjunction with what we had before might be the answer.

     

    CBR

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    In fact if you go onto Chris Schmidt's NAB presentation RIGHT NOW he is talking about another way to solve a very similar setup with softbody splines !

     

    CBR

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    Here we go - here's your scene working properly with that initial setup...

    Position of rail spline vital to fixing the poly twist glitch.

     

    SD_drape.thumb.gif.c05a79b70fc2d524f4d8961a761ec193.gif

     

     

     

    Note viewport speed is unhelpfully slow with L3 SDS everywhere, so have reduced that to L1 whilst tweaking dynamics.

    Still convinced we can eliminate that step and get this better and faster with a Mesh Deformer in the mix...

     

    CBR

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    2 hours ago, bnine said:

    I could not figure out how to anchor the first vertex to hold everything

    In the spline dynamics tag you can select a point and click Fix Points to anchor it, which is what we have done here in our tests.

    You may not want to do that. You might need to clamp that first point to a specific part of the watch instead, which you can do with a Hair Constraint Tag.

     

    CBR

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    Thanks for filling in the gaps for me, @Cerbera!  I had tried to reply, but must not have hit "submit" or something.  I've been a bit out of commission the last couple days.

    Is this working well enough for you, @bnine?  I noticed there is still some subtle bending of the geometry, but maybe it's not noticeable enough in a render to bother fixing?

    One idea I just had if you did need to fix it is to use three linear splines- one for each row of links.  Then you'd just carefully subdivide your spline to only have points between the links of the corresponding chain, so it wouldn't be a smooth curve.  Maybe even 2 points for each gap in the chain?  Not sure.  You'd have to make sure to keep all the other parameters for the Spline Dynamics tags exactly the same though.

    The only other option I can think of, which would probably be the "proper" solution, would be to link each of these pieces with a Connector object in Hinge mode.  You'd get rid of the Spline Wrap all together and have zero deformations of your mesh.  Sounds like a pain to set up though...

    I was messing around with Cerbera's file and did find a way to at least allow for some slight twisting of the band if your collision geometry isn't uniform.  Just using a second dynamic spline as a rail (had to adjust some orientation and stuff to get this working).

    Setup Better V2.c4d

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  • Hey @natevplas! Thanks for your reply and sorry for my late one. I haven't had the chance to look at the last file you sent but I will this week and come back to you as soon as I can. Thank you for helping me out with this, I feel I learned a lot by your first file/reply post and can't wait to open the second one :) 

    Will reply soon! 

    Thank you :) :) 

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