Biped planted key snapping/wrong position

SimonT

Hi, i made this picture to show which problem i have. Short: the position at the end (planted key) is wrong after i animated something in the middle (sliding key). I searched the web and also the max documentation but there only is written: "use planted key when the foot shouldn't be moved". Period.

Oh and sometimes i try to move the foot, set a planted key and it snaps back to its old position! No idea why!!

Warheart

Planted keys are for sticking the foot position in place (sticks to the position on the previous keyframe). Planted keys will stick to the last sliding key if I remember rightly. So sliding keys are for sliding the position of the plant. If you set a planted key after a sliding key and then change the sliding key, the planted key will update to the new position of the sliding key (keeping it in place).

When you set a planted key it switches on the toggle "Join To Previous IK Key". This is why it changes when you change the previous key.

Search for "Key Info Rollout" in the help and it will help you understand how to use the different types of IK key in biped.

Mark Dygert

Yep Warheart is right. Planted keys respect sliding keys. Any key you "plant" after a sliding key will use that new position.

Sliding keys are created automatically if you set a planted key then on a different frame you move the object.

The main purpose of planted/sliding keys in the feet is for a walk cycle.
You plant the heel on the ground in front of the character.
You slide it back behind the character.
And set a free key so you can bring it up and forward again.

If you want your foot in that example to plant, move away, AND then come back you need a free key after the sliding preferably in the position you want, you can then follow it by a planted key again if you need to.



The two free keys (gray) are identical, in fact I copied frame 0 to frame 1, 10 and 11 and then set a planted keys on 1 and 11.

Oh and sometimes i try to move the foot, set a planted key and it snaps back to its old position! No idea why!!

You need either a sliding key or a free key between planted keys. If you have two planted keys in a row the new planted key will get its position from the old key. It's how you stick a foot in place for a given time frame. If you want to move the foot and plant it in a new position use a sliding or free key between the planted keys.

SimonT

Thanks guys! Now it's much clearer! I don't know why the 3ds Max help can't explain it so clear like you did

SimonT

Another Question:

When i animate an arm with "separate FK keys > [X] Arms" it works good for e.g.the shoulder bone but when i move the hand it snaps always back the last position. Even if i activate "set parent mode".

Mark Dygert

The arm is its own system, from the shoulder to the hand. If you set a key for the bicep the "arm system" gets a key. Planted keys are there for the hands and feet only. You can't lock down a elbow or a shoulder, it will always lock down the hand.

If you into the Key Info Rollout > IK > click the box next to Select pivot. You see a diagram of a hand and the places you can set the pivot point for planted keys (time slider needs to be on a planted key for it to activate). Notice it only shows the wrist palm and fingers... no elbow or shoulder... heart breaking and headache enduing I know. Really 6 positions for the palm but can't include the shoulder or elbow? REALLY!?

I would LOVE to be able to set planted keys for any joint... it would so rock and I've wanted that for a very very long time. There are times I want someone to rest their elbows on a table, can't lock it down. Or someone is kneeling, can't lock it down, have to fake it... oh what a pain that is too...

SimonT

Thanks for the answer!

monster

Hey Vig,

I just started using Motion Builder off and on. My favorite features are planting any joint by Position and/or rotation and full body keys.

SimonT

Information i just found out:

If you hate that the hip is moving around when rotating the spines - you have to set "Key Info" > "Body" > "Balance Factor" to "0".

(there is a good explanation in the max help)

Mark Dygert

Monster, Yea motion builder is great! But we don't have it at work... I really like being able to stick any part of a rig to any other part of another rig, great for fighting sequences. By full body keys do you mean their full body IK system? Because that's pretty awesome too, or did you mean there is a way to set keys on all the body parts?

SimonT, ahh good tip, had to read up on it tho, heh.