Follow an animated path

[Anonymous]

Hello, I have an helix path which rotates around its own axis,

I need that an object (a dummy for example) follows the path in z-x axis, while the helix turns, driving up the object.

I attach an image to better explain

Any help for this?

Thanks

Rossano

[Anonymous]

Hello, rossano

I hope I can offer some assistance and pardon me if I use something you have already attempted. I see it's been a few days so hopefully you may have already discovered your solution and if not that someone here can help. I hope I understand as well.

The helix animation can be animated just by keyframing and rotating it and should be fine, but the object will be animated to follow the path. I don't think the animations will conflict so it should be good.

I would click the object and add a path constraint.

Animation menu >Constraints / Position Controllers > Path Constraint

You will see a percent in the follow path options which if you adjust will determine where on the helix the object will begin. So you may at first see the object in a weird spot, like perhaps midway on the helix, so adjusting the percent will help you place the object where you want it.

Then you can turn on keyframe and animate while adjusting the percent. There are also options for the orientation the object will have on the path. You may also need to select an option that says "Follow Path"

[leeminardi]

Expanding on what nada suggests, if the helix contains 5 full revolutions then the helix must rotate 1800° for the sphere to make it to the top.  If the entire sequence were 100 frames then the sphere should be 20% along the path at frame 20, 40% at frame 40, etc.. (In reality, the length of the helix for each revolution gets smaller as the helix radius decreases but you do not need to account for this). I originally key-framed the position of the sphere at 10% increments.  This worked fine for the range 10% to 90% but there was some wobble at the very beginning and end probably due to some non-linear interpolation after the first and before the last key frame.  I was able to eliminate most of the wobble by adding a few extra key-frames.

.

[ShaunBrettig7993]

Hi,

You do not need to use keyframes.

The following method will work as long as the helix animation and the following objects animation match.

1. Create Helix, based on using 5 turns

2. Create following object, suggest point or dummy

3. Create path constraint from following object to path

4. Setup Helix animation, rotate in z-axis 5 * 360 = 1800 over (x) frames

5. Open the curve editor on the Helix, I set the tangents for the start and end to be slow but you can set it to whatever you need.

6. Open the curve editor for the following object

7. Select Path Constraint > Percent in the curve editor

8. Right click Percent and select Assign Controller

9. Select Bezier Float

10. Change the Percent curve to match the Helix animation curve in the curve editor

11. With the following object still selected, goto the Motion tab and for the Path Constraint turn Constant Velocity off

Step 7 - change the constraint type from constant to bezier float and modify the curve to match the helix curve

Step 11 - Constant Velocity switched off

Regards

[leeminardi]

Thanks Shaun.  I forgot to mention that it was key to uncheck Constant Velocity.  My animation worked fine without key frames for the middle 80%. In reading your solution I noticed that you used Position List for the Position Controller.  When I changed from Position: Path Constraint to Position: Position List then my animation worked correctly without the additional key frames. At what point did you specify Position List and what does it do?

[ShaunBrettig7993]

The Position list is automatically used when you use the Constraints > Path Constraint menu item on the object to constrain to the path.

It enables you to add a list of position type constraints to your object.

So you could do the following if you wanted have an item centered between two other objects and have it bobble around as if some air turbulance was hitting it.

1. Create 3 spheres

2. Select Constrain > Position Constraint from 1 sphere to the other sphere

3. In the Position Constraint on the Motion panel, Add the other sphere

4. Now move either of the target spheres and the constrained sphere will remain in the middle

5. Select the constrained sphere, In the Assign Controller > position list select the "Available" list item

6. Click the Assign Controller button

7. Add the Noise Position

8. Animate the position of either one of the target spheres to see a sphere remain centered and bobbing around.

As far as the Helix solution is concerned the main thing which makes this work is the animation curves of the Helix and the following object match each other. (This will work if both are linear)

Whenever you create a path constraint it will always be linear and when you create the rotation animation of the helix it will always be whatever you have set it to be.

To help match it you need to convert the paths controller type to a Bezier as this type matches the curve type of the helix rotation.

[leeminardi]

Thank you for the explanation. I was able to get the desired motion without the Position List and just the Path Constraint since there is only one constraint for the object.  I am using 2014 so some of the controllers have a different names (e.g., Noise Float vs. Noise Position).  Thanks again.  YOu have given me a better understanding of these controllers.

[ShaunBrettig7993]

No problem, glad I could help out.

Yes, I'm using 2015 and developers have been changing the names to be more consistent in respect to each other, but the controllers still do the same thing between each of the versions.

Yes, you can do without the Position List in this instance, it has no effect on the end result, but for the example I gave using the noise modifier, it is a nice clean way of handling this type of animation, you can get exactly the same result using different methods.

In the end, whichever way works and doesn't drag down the processor time is good. 😉

Regards

[Anonymous]

Thank you all for your answers.
I solved the problem in another way but your information I will certainly be useful for another project.

Thanks to all

Rossano

rendermotion.it

[Anonymous]

I'm glad you found your solution. It's amazing how many ways there are to do things. I have learned things as well