Cineversity

To Whom It May Concern

I’m trying to animate a crane. I want to fit the location of a support as the upper arm rotates downward. So that the piston stays fixed in its current position and follows the movement of the upper arm.

I could keyframe the movement but there must be a more elegant solution, perhaps an XPresso script?

Thank you

PS. I’ve attached a sample file to illustrate the problem.

Hi marcpurcell,

I would love to answer, but there is no file. More often than not in the past month, my own “zip” files were rejected based on MIME type problems.

Would you mind to try again, or do it via one of the “cloud services”, e.g., Drop-Box?

I have create a file—in the way I have understood the wanted set-up so far, and you can tell me what is different to your idea. So we can get what you like to have.

Rotate R.B of “Null.1” IF all needs to move, place it under a Null Parent and move this object.

All the best

Alternative to the “classic” set-up is the use of an MoGraph Tracer.
Let me know what works for you, or if something else is needed.

I so impressed by the quality and speed of your response. Thank you. The first example is perfect, but could you explain how it functions?

Again thank you.

Thanks for the feedback, marcpurcell.

The idea is to have a Target on one side and something that “looks” to that target. Then do the same in the other direction.

The problem with those set-ups is since ever, that they create a problem: in a certain position it rotates around itself (Euler Angle). Hence the intorduction of the UP vector. The missing stability is back with such a “three-point” set up (Root Null or Parent), Target and Up.

If that was too short, to communicate this set up, let me know. I have created a scene file to illustrate this, each follows the other one. ;o) Just let it play in “View: Right”

All the best

Thank you again

I have one follow up question. The rotational value of the Nulls has an impact on the function of the rig. When I set up the rig with the same rotational values as the sample file you sent it works fine. I was just wondering how and why the Null’s starting rotational value impacts if the rig will work or not.

Hi marcpurcell,

Would you mind to share the rig that causes you trouble, with a description of what you like to do.

I have only a single Null with manual adjusted rotational values—the one that has to move in order to lift the goods (speaking of a crane).

Any other Nulls follow the Target Tag if needed.

To rotate or move the whole ri, place everything under a Null (I do not suggest to use the “Group” shortcut for this.

In the moment I have more informations about your targets, I will be able to be more specific.

All the best

Sorry if you receive this twice. I wasn’t sure if the post worked.

When I select the Null_Target_2 object’s Target tag and drag the Null_Target_1 into the Target field the mesh of the shock object flips. Not sure why? Can you explain what happening? The rig works when I rotate or set up the Null objects axis to match the sample you sent. But I not sure what’s happening.

Thank you

PS – I’ve attached the sample file. Please let me know if it doesn’t arrive.

No worries about twice or not, marcpurcell.

In the Target-Tag should be the Null with the “axis” inside of the name. That Null goes into the Target, “up” of them same group goes into the Up-field.

Again, to be clear, target “axis” from the other group, “up” from the same. Or axis-1 needs to target axis-2. Vice versa.

The up needs to be in distance, so the three nulls (axis-1, axis-2, up) create a triangle. This triangle makes it stable, like a door, with to joints and a handle/knob.

I have named in the scene now the important parts 1 or 2. I hope it is clearer now.

My best wishes

Did you receive the file I attached to the last post? My setup is correct, but on my file when I place the Null object in the UP Vector field my piston rotates to an odd angle. I do have a working version, but I need to align the null to the same rotational value as your sample. Just wondering why the my piston arm is swinging to an odd angle.

No file, only an hint that you liked to add one. If you can’t see it, then it is not there. Often the server doesn’t accept files (I requested a fix for that yesterday).

Do you mind to try again or do you have an upload option?

I stay tuned. :O)

I’ll try uploading the file again. Is there another option to send a file to you?

Hi marcpurcell,

Here is your file back. I have put it apart, set all the scale to 1, adjusted all axis/angle, as well as all rotational/target Nulls to z=0 so they are on on “virtual” plane.

After all parts are in they way I wanted to have them, I started to set up a new hierarchy. This is in my understanding how it has to work, following a certain logic. Any change in the hierarchy should be done with a copy, just in case. I hope it “reads well”. :o)

Have a look to the HUD adjustments. You can set keyframes directly there. All other parts are in the Layer Browser. As a little bonus—I have set up the hook/chain so it is always vertical. If you don’t like it, delete the XPresso tag.

I think the slide arm could need some “air”/adjustment, but that is certainly not part of the question ;o)

My best wises for the project