Sliding and planted keys !!!

[gaggle]

Something like that, yeah. There is an element of setting keys that affects the next key in there. Changing the pivots around on the foot involves setting the pivot on key A, and then using that pivot on key B, for example.

A.. wuz it called, locked key?, snaps the limb to the position of the previous key. A planted key activates IK, thus the foot sits still despite bodymovements, and a free key is as if the foot is in FK mode.

It works very nicely once you get into it I think. Fairly efficient workflow.

[Mahlon]

Yeah, once you get in the groove, it's pretty cool. I like it. Here's some more info for you from the CS4 reference:

Biped's inverse kinematics solution has three parameters set at each key of the arm and leg keyframe tracks. As the limb moves through each key:

IK Blend sets the motion interpolation to be a blend of forward and inverse kinematics. This allows you to blend swinging motions with hand-or-foot directed motions. Rotating an arm to move a hand is an example of forward kinematics. Using the position of the hand to move the arm is an example of inverse kinematics. The default blend is 0.0, or full forward kinematics. An IK Blend of 1.0 is full inverse kinematics.

Body or Object determines the reference coordinate space of the IK path. This allows you to move the IK path with your character's body or temporarily attach the hands or feet to follow other objects. The default is Body.

Join To Prev IK Key determines if the key should be part of the previous key (and have the same reference position as the previous key).

Biped has three automatic ways to set these parameters. Setting planted, sliding, or free keys creates keys with different combinations of these three parameters.

Setting a planted key creates a key with IK Blend set to 1.0, Object and Join To Prev IK Key turned on.

Setting a sliding key creates a key with IK Blend set to 1.0, Object turned on, and Join To Prev IK Key turned off.

Setting a free key creates a key with IK Blend set to 0, and Body turned on. Join To Prev IK Key is turned off.

IK Blend can be set per key for any arm or leg track. The IK Blend setting determines whether, at a particular key, an arm or leg is moving through it using inverse kinematics, forward kinematics, or a blending of the two kinematic solutions.

An IK Blend value of 0.0 means full forward kinematics. The arm (or leg) is moved by interpolating the rotations of the joints at the keys. The hand (or foot) tends to move along sweeping circular arcs in this case, and the motion appears to be motivated by the apparent swinging at the joints.

An IK Blend value of 1.0 means full inverse kinematics with the hand (or foot) being used as an end-effector. A spline path is computed through the keys of the hand, and the hand moves along that spline. Joint angles for the rest of the arm are computed to allow the hand to follow the spline. The motion, in this case, appears to be directed by the hand (or foot).

An IK Blend value between 0.0 and 1.0 means a combination of inverse and forward kinematics; when IK Blend is closer to 0.0, forward kinematics are more heavily weighted in the solution, and when IK Blend is closer to 1.0, inverse kinematics are more heavily weighted.

It is best to use forward kinematics when you want the arms to swing, such as when a biped is walking. In the case of a boxer, however, since the hand should follow a directed path when punching, inverse kinematics should be used.

Join to Previous IK Key

This IK constraint is used to specify if a footstep is sliding or planted. If Join To Prev IK Key is on, then the biped foot maintains a reference position to the previous key, keeping the foot planted. If Join To Prev IK Key is off during a footstep, then the foot can be moved to a new position creating a sliding footstep.

Join To Prev IK Key also functions to lock the biped hands in space. Use Set Planted Key on the biped hands to lock their position in space.

Tip: If you are having trouble with a foot or hand popping back to a previous ‘keyed’ position, check to make sure that the Join To Prev IK Key is off, especially when you're using pivot points.


Mahlon

:beer:

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.