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BLSmith

Modelling a not-so-traditional spring

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Hi all. I am trying to model a not-so-traditional spring. It angles upward, it isn't perfectly straight, and it has two elongated hooks on each end. I'm curious how I'd go about modeling this. Here is a short video that gives proper context, and I've included the file below.

 

Thank you all and I look forward to your replies!! 

BLSMITH C4DCAFE THROTTLE SPRING QUESTION 1 V2.c4d

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No, Smith, what ARE you doing !??? 🙂

(...other than once again taking my yearly award for 'best explained post' !) 

 

What we could do instead is spline wrap the spring coil along a length of secondary spline that makes it assume the right shape !

Hang on, I will do some tests, and see if that is feasible, or if something we need it to do later might compromise that approach...

 

CBR

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Yep, that basic plan seems to work very well at stage 1...

 

image.thumb.png.88e15b6b43d524a6b7713c8fb496a978.png

 

...but what will happen when it all starts to move ?! I need to stare at that movement for a few minutes more, but I think I see a plan forming...

 

CBR

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OK - remember when we build the first bit last year - we're gonna do largely the same thing again, and I think it's going to be a remarkably similar set of stages to get there.

 

So those stages might be:

 

Modelling:

 

1. Make a simple path spline that we can use with Spline Wrap to direct the body of the spring.

2. Do that spline wrap then adjust various parametric helix parameters so ends are positioned suitably to join the end pieces (separate splines initially).

3. Make spline paths for the hooky bits (could even use existing geo to generate them), COaD the splines together and weld the points.

 

Animation Setup:

 

Like last time we should deform the helix, NOT the swept result, so we need to do the following:

 

4. Get a copy of our spline, move any existing animation timeline to the correct point that identifies this component's furthest required reach at the end of its movement cycle. 

5. Use that to physically alter the second spline so it remains in the right holes as it moves, then pose morph that with the original spline.

6. Moving the Object Axis so that 1 end remains fixed, and rotation from that point can be correct and the hole up the other end still aligns.

7. Keyframing those morphs and rotations in sync to get the animated result we want.

 

So, I guess the most prescient question to ask now would be 'given that this was all mainly stuff I showed you how to do in detail last year, how much of the minutiae involved in doing it do you remember ?!'...

 

CBR

 

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OK, I just loaded our project from last year and see that we used an FFD on the spring, rather than the point-based Pose Morph I am suggesting now. I suspect FFD won't do in this case because the movement is a bit more complex, and FFD would distort our spline in a way that a PM won't.

 

So now, I need to add another question to the above, which would be 'are you cool with sorting out point based pose morphs ?' ! 🙂

 

CBR

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I made a one hour long private(ish) tutorial for myself to summerize what we did last year. I was about to re-watch this but I see in your new reply that we used FFD not Pose Morph, though I remember doing something with Pose Morph once over a year ago but I'll have to look into where I did that.

 

 

I'll also look up videos on what spline wrap is, as I've never used it before. I apologize but the term definition for "COad," and 'welding the points,' eludes me. As I read your replies I decided to record my reactions to each including the actions I tried to take to follow them, so this video below is not required, but merely encapsulates what I feel I need to do over the next 24-48 hours to try and get a better understanding of what needs to be done.

 

 

I'll reply back with a new update then, thanks Cerbera! 

 

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Just skimmed through my summery video in the reply above and noticed I do dive into pose morphs. I'll rewatch that tomorrow AM and recreate it from scratch and reply with an update! 

 

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I can help if you like...

 

For example, here is my file that shows the spline wrap setup...

 

Unusual Spring Stage 1 CBR.c4d

 

and shortly will arrive a video explaining Spline Wrap, and the bits of it relevant to us now, which will be here in about 10 mins...

 

 

Couple of notes to add since that was recorded....

 

1. I didn't pause to change the interpolation on the path spline we used for the wrap, which means our deformed result goes round corners a little sharply. So we should select those middle points, and set them to be soft interpolation rather than the hard points we have now (select points and r-click to change)...

 

2. COaD is short for Connect Objects and Delete available from the r-click menu when objects are selected in the Object Manager.

Does exactly what it says on the tin, but doesn't join the actual points, so they need welding next, which is simply where you join the end point of 1 spline segment to the end point of another.

 

 

CBR

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For me FFD way could be just fine. With FFD can be "simulated" stretching in place where is physicaly touched of linkage and could looks more realistic like spline wrap...

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Reply to @Cerbera:

Thanks Cerbera for the file and video! It helped a ton. I spent about 6 hours on this today and I came up with a nice solution:

Here is a file of what I came up with. Unfortunately the file size has gone up from 2mb to 200mb so I linked it on Google Drive:

https://drive.google.com/open?id=1X75mKu1v5ydDVd0RQYvaDYH1kN31Xe-f

The text summary: 

  1. Glad you don't have corona Cerbera 😉
  2. Noticed while having the helix selected, I couldn't shift+click to adhere the spline wrap bounding box to the helix. 
  3. Had to CTRL+click the helix, manually drag the Spline wrap under the helix to achieve same result.
  4. Connected all objects and delete (COAD) at the end and added an FFD, although the FPS went down considerably. I've included that in the file above. 

The video summary (optional, covers same information as text summary):

 

The entire process of me figuring this stuff out and coming up with my solution (I don't advise this be watched, but it's here for completeness):

So at the end of the day, we have an animation that looks good and I suspect loop good but it's difficult to know with a frame-rate that used to average 30 now averages 2, but it's a solution and I will run with that. If you'd like we can try to optimise this but I do have to move forward with the project and show progress to my boss. 

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