View Full Version : Following a goal

09-30-2010, 09:04 PM
Feel free to laugh at me as I am no expert in Lightwave, though I have dabbled with it for years.

My problem is this. I have a character operating a floor sander. Very basic and character animation is something I have rarely touched. I have set the character and sander up so that if I move the sander back and fourth, the handle tilts back toward the character, and his hands keep hold of the handle and his arms bend appropriately..... BUT..... this only works when I am physically moving the sander. If I render the scene, the rendered image shows the hands by his side and not on the handle. If I move the frame slider, the hands also jump down to his sides, and dont stay on the handle, but if I re-position the base of the sander, the hands once again return to the sander handle.

I have a skeleton in the human body with individual fingers. I have a wrist bone which has a goal (Null Object) as well as a 5 finger goals (again null objects) to get the hand steady on the handles of the floor sander.

The Sander is a 2 layer object. 1st being the base, the 2nd being the handle. I have set the handle to point to a target which I place between the sander and the human form. As the base is being moved, the handle tilts nicely. I have created a null called "Right Targets" for all the hand goals which I have positioned appropriately near the handle and is now (a) A CHILD to the Handle layer of the sander and (b) a PARENT to all of the finger goals.

As the sander base moves, the handle points at the Handle Goal and tilts, the hands grip the handle and move with it all very nicely, but as soon as I move the frame slider, the hands snap down to his sides. They move a little but not even close to the handle.

Also, if I reposition the base of the sander (tilting handle and hands in position nicely), the rendered image still shows the hands by his side.

I am sure that you are all laughing insanely at me as I am quite the novice and are yet to learn as much as I should, but this concept seems so basic, and the fulltime IK reflects the results I want while I move the sander into position so I know its works, but I am missing something that undoes it at render / frame advance time.

Any help would be appreviated as I am pulling my hair out.

Basic rigging is as shown below and I have also attached an image of how it looks in layout, and how it renders, or changes when I move the frame slider... and my apologies in advance as this is my first post on here.

Many Thanks.

Fingers (each finger has a bone with the appropriate goal set)

Sander base
Sander Handle (With Sander Handle Target (null) set as target
Right Goals
Right Wrist Goal (Null)
Right Palm Goal 1 (Null)
Right Palm Goal 2 (Null)
Right Palm Goal 3 (Null)
Right Palm Goal 4 (Null)
Right Palm Goal 5 (Null)

Sander Handle Target (Null)

09-30-2010, 09:20 PM
I had tabed everything in to show heirachy but when I posted it they all justified left for some reason... so here it is again.

-->Fingers (each finger has a bone with the appropriate goal set)

->Sander base
-->Sander Handle (With Sander Handle Target (null) set as target
--->Right Goals
----->Right Wrist Goal (Null)
----->Right Palm Goal 1 (Null)
----->Right Palm Goal 2 (Null)
----->Right Palm Goal 3 (Null)
----->Right Palm Goal 4 (Null)
----->Right Palm Goal 5 (Null)

Sander Handle Target (Null)

09-30-2010, 10:30 PM
Auto keyframes? Do you have it on? Did you keyframe your nulls anyways?

09-30-2010, 10:45 PM
Though I have Autokeyframes on, I have tried this with and without some form of keyframe on various elements. Right now there isnt a single keyframe, just a static image, but again, I have added keyframes and no luck.

Its just weird because when I move the sander with the mouse, the handle and arms move exactly how I hoped they would...

09-30-2010, 10:48 PM
Just a note... if I keyframe movement in the sander back and fourth, then move the slider, the guys arm does move back and fourth a little, though it is by his side as though it was being drawn hard toward his own pivot point and receives just a little influence from the goals on the handle. Perhaps this makes sense to someone.

09-30-2010, 10:58 PM
There is a slim possibility that I may have worked out the cause, though judst trying to figure a solution. I use a target to point the handle at. I had to rotate the handles pivot point so it was pointing int he right direction, and I think that has something to do with it as the hand seems to be pointing to a spot as though it is just looking at some random rotated part of the handle (if that makes any sense).

Working on it now....

10-01-2010, 10:48 AM
Can you post the scene file? Replace the objects with nulls so you don't have to send the objects too.

My first impression is that your rig is really complicated.

10-01-2010, 11:09 AM
I agree, sharing the scene would be a constructive step in order to solve the problem.
Otherwise we just have shrewd guesses.

10-01-2010, 12:35 PM
Your using LW 9.0 targeting and IK do not work well in older version for LW. If you're stuck with 9.0. Then switch you're targeting to use IK instead.

Second you need to set the "root" of your IK chains. In you're screen shot you can see the blue lines going from your base of your char to the end of each IK chain. In your setup this is in not what you want. So what you need to do is set the root of your IK chains. (Shoulder to wrist) and (wrist to finger tip). To set the root of your IK chain you need to turn on "Unaffected by IK Descendants".

So on the parent joint of your shoulder(clavical). Turn on Unaffected by IK Descendants". You will see your blue line start at the shoulder and end at the wrist. Repeat the same for the fingers. So on the wrist joint turn on Unaffected by IK Descendants"

10-05-2010, 09:24 PM
Thank you for all the suggestions. As it turns out I have found a solution. Not the ideal one, but one that works for me on this occasion. I am pretty sure that my problem is related to using a target on the handle and having to rotate the pivot point to make it point in the right direction, so I removed the targetting and set the handle tilt with keyframes. As it turned out it gave me more control over the guys "pushing" action, and solved my problem.

This is the first time I have posted any help question on any forum and I am pretty impressed at the support that came through so fast, especially for someone who knows so little about LW.

Many thanks.