IK/FK snap

[knucks922]

I created an IK/FK snap setup using the fahrenheit digital tutorials and everything works perfect on the left side, but when I try to create the same thing on the right side it fals miserably. I notice that original length is negative and that the fk length is the same number but positive and I'm wondering if that is the problem.  I've tried everything I can think of to fix it but to no avail. I"ve spent the past 4 hours trying to get it right, it would be amazing if someone could help me fix this.

[omkar-jere]

Can you provide the scene file I can check for you if you wish.

[knucks922]

Absolutely, that would be amazing thank you.

http://www.4shared.com/file/Igp1Hl8O/thairig\_arms\_v20.html

[omkar-jere]

I'll start working with the file just need some info what is the exact problem as well as when does it occur Fk to Ik snap / Ik to Fk Snap ? this will help me focus on that immediately

[knucks922]

Excellent! The problem lies in the right arm IK/FK snap set up. For some reason when I test the IK/FK snap for the right arm joints the bones translate and scale weird, like backwards.  I noticed that on the original length attribute that I set up for the IK joints the value is negative, but on the FK length attribute of the joints its positive.  That may be the problem but I'm not sure. The problem may lie in the multiply divide nodes too, I can't really be sure, I did exactly what it said to do in the tutorial, but I think I may have had to do things differently for the right side joints.

[omkar-jere]

Can you provide the script you used to switch that may also have caused problems ? I checked matching both with my script it works OK so maybe something wrong in your script.

[knucks922]

I actually never used a script to create the switch, I moved and scaled the appropriate FK joints, point snapped the IK handle of the IK joints to that of the FK joint, then manually inputted the values of the "FK length" attribute into the translate X of the IK joints, and thats when they went haywire. I havent built the full rig yet so I haven't needed to use the switch script provided by the tutorial.

[omkar-jere]

Ok now I understand your problem is that IK strecting is getting controlled by the scaleX and not translateX when you move the ikHandle away the joints should stretch properly its setup that way. Don't try and match Ik to Fk stretch yet because with that rig it may not be possible. Only match the poitioning of the rig and not stretch

BTW don't mind me but that DVD(Farenheit Digital - Rigging for Animation) is actually quite confusing I had issues with that too. so recommending not to rely too much on it. If you're really serious about rigging then go for Animator Friendly Rigging in Maya by Jason Schleifer its THE BEST DVD for Rigging in Maya till date.

Good luck.

[knucks922]

Thank you! I still am not sure why it works perfectly on the left side when I do this but not on the right, any ideas as to why that is?

[knucks922]

ok so I think I half figured it out, this is what I did:

1. Create 3 multiply divide nodes, -n armFkLen01-03

2. connected each armfklen_md 1X into the "distance" of the 3 dist shape nodes

3. connected each output X of the multiply divide nodes into each of the "fklengths" of the arm joints starting with joint02

4. loaded armLenSum_pma node into inputs, connect joint02 "fklength" into the input 1D

5. opened script editor, copy "connectAttr -f thaik_r_arm02_ik.fkLength thaik_r_armLenSum01_pma.input1D[0];" and replace _arm02 with _arm03 and _arm04, then replace .input1D(0) with .input1D(1) and (2) to connect attributes.

This gives me the negative values I need but for some reason the arm still isnt doing what it is supposed to

[omkar-jere]

Post some screenshots when you're move the hand make sure the channelBox is visible in those. That way it would be very clear. Also try and post some of multiplyDivide nodes in Attribute Editor.

[knucks922]

ok, I hope these help:

You can see that the IK joint is scaling past is handle and just generally not matching up to the FK and JNT joints, I'll also include the updated scene file:

http://www.4shared.com/file/6koAm7IJ/thairig\_arms\_v26\_FKnodes7\_test.html

[omkar-jere]

With the updated scene file that you provided I tried matching the right arm (without stretch) but was unsucessful. The solution i found is:

1. Delete the ikHandle for the right arm.
2. Select first 3 Ik Joints for right side and rotate them forward (negative Y axis).
3. Then goto Skeleton > Set Preferred Angle.
4. Apply a fresh ikHandle and test.

Earlier it used to be offseted even without stretching(right ik arm) now it matches well. Try setting the stretch for right side as you did on the left after doing the steps above.

Good Luck.

[knucks922]

Thank you! I think I have to delete the whole arm and redo all of it because of cycling connection issues (I tried just deleting the IK handle and re-connecting everything but it wasnt working out well) So it may take a little while until I can confirm whether this worked or not, but for some reason I have a feeling it will.

[knucks922]

I keep trying to fix this, but then more problems arise. I think I'm just going to scrap the entire rig and start on that Animation friendly rigging tutorial.  Does he teach the same things? Like the ribbon spine and ribbon bendy arms and IK/FK switching with scale and all that?

[omkar-jere]

Animation Friendly Rigging doesn't have Ribbon Spine but has Fk+Ik spine setup as well as Fk/Ik arms setup and much more the difference here is how it is tought its really awesome and detailed. There are some parts on the series which are a bit difficult to understand but after you watch it a couple of times then you realize how powerful/flexible that setup is and you simply start loving it.

[knucks922]

I went back over and re-did the entire arm rig for the 40th time, and it worked this time, I didnt even have to create those multiply divide nodes, it was all in the preferred angle, thank you!

[knucks922]

Once I complete this fahrenheit digital rig (unless I run into a huge problem I cant solve) I'm going to go through those animation friendly tutorials.

[omkar-jere]

Glad to hear you problem has been solved, As far as the rest of the DVD is concerned good luck for that.

[knucks922]

Already ran into another problem, but this one seems like it should be less complicated, I'm at the part of the DVD where I essentially re-orient my leg joints using an aim constraint, aiming one joint to the next with a locator being an up vector. The process goes as such: unparent one joint from the other, open up attribute editor, zero out its joint orients, snap the locator to the first joint, translate it out in X, aim constrain joint 2 to joint 1 with the locator as the up vector, move the locator back in Z to orient the joint, delete the aim constraint, select joint 1, open attribute editor, copy the new rotate values and paste them into the joint orient boxes, zero out all the rotate values, then once you've done this for each joint, re-parent them together. All of this has worked fine, but when I try to create an IK handle, the pole vector doesnt match the orient of the joint, its like offset or something, I have a picture of what I'm talking about, if you could help me fix this I think I should be good to go.