topic Re: First timer rigging a lamp, trouble with IK (Possible solution) in 3ds Max Animation and Rigging Forum

First timer rigging a lamp, trouble with IK (Possible solution)

Anonymous — Tue, 04 Dec 2018 10:48:57 GMT

I'll be posting several images.

I know there's an easier way to do it, but this is my first time rigging and I want to try as much as I can to think outside the box.

My issue is this, I'm following a tutorial on IK solving a neck for a lamp to bend. My issue is that several parts of the lamp are bent as part of the design, this pushes the bottom neck out to the side. I have my pivots and IK solver in place but when it bends, the whole thing twists.

I have an idea. Instead of linking the pivots, I was thinking of linking the pivots (Which are at different distances) to dummies which are perfectly lined up. THESE are what I'll be using instead of the actual pivot screws on the lamp to try and get the IK to line up right.

I'm sure it'll fail, but I don't know what else to do.

Re: First timer rigging a lamp, trouble with IK (Possible solution)

Anonymous — Tue, 04 Dec 2018 11:21:19 GMT

UPDATE: It works so far, It's hellishly unorthodox but it works

Re: First timer rigging a lamp, trouble with IK (Possible solution)

leeminardi — Tue, 04 Dec 2018 14:53:24 GMT

It is important to understand that the HI IK Solver works in a 2D plane. If that plane become skewed in space the links of your lamp will twist. The best way to address this issue is to use a point reference to help define the IK plane and keep it vertical. Add a point in space above the lamp's base so that when you rotate the lamp the point will keep the IK plane vertical. Sometime it is necessary to link the reference point to another object to ensure the IK plane keeps the orientation you want.

Re: First timer rigging a lamp, trouble with IK (Possible solution)

Anonymous — Tue, 04 Dec 2018 15:42:46 GMT

I'm glad you mentioned that, I discovered that shortly after my post. I'm good on that front.

Now i'm at another problem.

Images attached. Right now I have my links and solvers ready. My lamp is parented to the joint for it, and that is connected to my IK. Meaning if I move the lamp the whole thing swivles. It's fun.

However, the top rail and back rail aren't connected at the tops, so when it moves the tops just stick out like a broken bone.

I heard the best solution to mask that is to "Orient constraint" the joints. I tried that but when I do that it flips just about everything.

Re: First timer rigging a lamp, trouble with IK (Possible solution)

leeminardi — Tue, 04 Dec 2018 15:47:40 GMT

It is difficult to understand your rig from a couple of pictures. Can you post a 2018 compatible version of the file? You will need to zip it before attaching the file.

Re: First timer rigging a lamp, trouble with IK (Possible solution)

Anonymous — Tue, 04 Dec 2018 16:00:09 GMT

Of course, Sorry. I hope this works.

Re: First timer rigging a lamp, trouble with IK (Possible solution)

leeminardi — Tue, 04 Dec 2018 17:44:54 GMT

You can think of the links of the lamp as three 4-bar linkages that are linked to each other as I show in the illustration below (I created this file from some objects I had for another project).

Select and move IK Chain003 in the attached file and watch how the other links follow.

If you do not know how to create a 4-bar linkage I suggest looking at this video I made some time ago. I used bones back then but you do not need to use them as is the case with the attached file.

I suggest first creating a simple 4-bar linkage like my #1 above. Then add the #2 linkages and finally #3. When you got all that working you can try it out on your lamp model.

I suggest you identify the links in your model that compose each of these 4-bar mechanisms. The pivot points for these object should all have the same x coordinate

Re: First timer rigging a lamp, trouble with IK (Possible solution)

Anonymous — Tue, 04 Dec 2018 23:35:06 GMT

Thank you so much for your help. I appreciate all the advice on this topic.