View Full Version : pulling and dragging an object

12 December 2003, 03:19 AM
Hi All-

I just completed an animated short. Watch this first and notice how much the horns are moving and twitching.

Wake Up Call ( (10.9 MB, divx)

The horns are parented to the hand bone. I used driven key's for the hand's rotation. So the hand is not rotated simply by using a locator. What is giving me trouble is that I have to key the hand's rotation every frame in order to keep the horn on the ground and steady. But I can't get the rotation perfect every time to keep it steady.

Is there a way in which I can use an aim constraint to force the hand's rotation to keep the horn's end planted on the ground to stop the twitching?


12 December 2003, 03:35 AM
first off, i took a few viewings to understand why he's thrown across the room, i'd change camera angles or something to help express it.

There is a plugin for letting you switch parenting. You can have a locator on the hands, the horn, and the floor, then switch between the 2 as needed.
I think it's called 'GRAB'.

Or just write down the translations, rotations for each key (granted you're using efficient key framing) and then just match the # changes of the movement of the locator to the movement of the horn locator.

12 December 2003, 03:51 AM
where can i find the plug-in? Or is it built-in to maya?

I am going to be a bit more specific about my rig. The arms are moved through an IK system. There is a locator which moves the position of the hand, and thus the horn. The actual rotation of the hand is moved through three driven key's, #1: hand twist, #2: hand up/down, #3 hand side/side. So I adjusted those three driven key's every frame in order to keep the horn on the ground and stable.

So there really isn't a need for unparenting the horn from the hand, when my guy is pulling the horn. The horn MUST stay in his hand. I just need a way to keep the end of that horn planted on the ground.

I am guessing that all you need is an aim constraint or something related to do the job. But there is no way (I think) to connect an aim constraint with a set driven key. Hidden in the connection editor?


12 December 2003, 08:03 PM
if I understand you problem.. and im not sure i do...
you may just need to constrain your object to 2 things and key the effect from one to the other (that is all the "grab" script (not a plugin) that neil is talking about does)

so, select the objects you want to be "masters" select the object you are constraining, -> create constraint.

the constraint will have 2 attrs, objects1WO and object2WO, they are the weights for those objects in the constraint...

hope that helped.

12 December 2003, 10:47 PM
How about using some IK?

Maybe you could make a 2 joint chain, starting with a joint at the position where the hand grabs the horn and one at the bell.

Then parent the Horn to the first joint, and apply IK to the joint chain.

Make a locator and place it in the part of the hand that grabs the horn and parent it to the wrist. Then point constrain the first horn joint to that locator. Control rotations of the horn by moving the IK handle and rotating the first joint of the horn chain.

If you need the position in the hand, where the horn is held by, to change, or maybe the other hand needs to grab, either simply animate the locator or add another locator to the point constraint on the horn joint and blend between the two.

Should work.. I think! :-) No 3D app. in front of me. Did something a little similar in max recently, and there I had to use a SC solver to keep the IK from doing unwanted rotations on the joints.

Hope you nail it,

12 December 2003, 12:44 AM

Sounds like a possible solution....I will give it a go!


12 December 2003, 02:14 AM
vrljc: The shaking would stop if you parent it. And keeping it on the ground is only a matter of keeping the hand IK at the same Y value.

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