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Inverse Kin channel node

Generates channels for bone objects based on a bone chain and an end affector.

This generator CHOP generates channels for bone objects based on a bone chain and an end affector. It can solve for the bone angles using a variety of different solver types.

Parameters

Kinematics

Solver Type

Specifies the solver to use to generate the channels.

None

No solver. Use the original parameter values.

Show Rest Position

No solver. Uses the rest angles.

Show Capture Position

No solver. Uses capture angles.

Inverse Kinematics

Uses IK solver. The solution is uniquely defined by the end affector position. Constraint parameters are ignored.

IK With Constraints

Uses a modified IK solver. The solution depends on the previous solution. Constraint parameters are used to limit the range of motion.

Follow Curve

The bones are positioned to follow the specified curve as closely as possible.

Root Bone

This is the first bone in the chain for which this CHOP should create solution channels.

End Bone

This is the last bone in the chain for which this CHOP should create solution channels.

End Affector

For Inverse Kinematics and IK With Constraints solvers, this is the object to use as the end affector when solving for the bone angles.

Twist Affector

For the Inverse Kinematics solver, this specifies an object that controls the twist orientation of the solution bone angles.

IK Twist

For the Inverse Kinematics solver, this parameter specifies an additional twist angle to be applied to the solution bone angles.

IK Dampening

For the Inverse Kinematics solver, this parameter represents how easily the End Bone can be pulled off the End Affector as the bone chain is stretched out.

Curve Object

For the Follow Curve solver, this parameter specifies the object that contains the curve geometry that the bone chain should follow.

Curve Normals

For the Follow Curve solver, this parameter specifies how the curve normals should be transferred to the bone chain. Note that the normals are interpolated on the curve between the curve breakpoints. Because breakpoints (and not control points) lie on the curve it is more meaningful to use interpolate the breakpoint rather than the control vertex values. Though, breakpoint normals are calculated from the control vertices.

Best Guess

the bone chain normals approximate the curve normals as much as the curve parameters allow. (Path parameters, for example, carry extra information that allow twists of more than 360 degrees)

No Normals

the bone chain maintains its own normals defined by the rest position.

Quaternion

the bone chain normals interpolate the curve normals using quaternion rotation of the vectors. (i.e., the bone chain normals lie on the shortest arc defined by two curve normals on a unit sphere.

Clamped Angle

the bone chain normals are calculated using twist angles around the curve (between the curve points at which a normal is defined). The angle difference is restricted to the interval between -180 to 180 degrees.

Angle

the bone chain normals are calculated using twist angles. This option is similar to Clamped Angles, except the twist angles around the curve are not restricted. Note, that for this option, the curve must carry additional information (see Object Path Tool). Otherwise, this option is downgraded to Clamped Angle.

Blend

This option blends between the local bone rotation values and the solved solution. When this value is 0 it produces the local bone rotation values and when it is 1, it produces the solved bone rotation values.

Straighten Solutions

When this checkbox is turned on, the bone chain will completely straighten out in the direction of the goal if the IK goal is farther away than the length of the bone chain (with a tolerance of the tracking threshold). If this checkbox is turned off, no attempt is made to further straighten the IK solution. By default it is turned off because it is faster.

Tracking Threshold Factor

This value specifies the accuracy threshold for Inverse Kinematic solutions. Use smaller values for more accurate solutions at the expense of more computation time. Use larger values to save computation time at the expense of getting less accurate solutions.

Channel

Single Frame

Only create one-sample channels, at the Start position.

Clean Rotations

When not in Single Frame mode, the CHOP can use the previous rotation values as a hint when generating the next frame’s rotation values.

Start

The start position of the CHOP.

End

The end position of the CHOP.

Sample Rate

The sample rate of the CHOP.

Extend Left

The left extend condition (before the CHOP’s start).

Extend Right

The right extend condition (after the CHOP’s end).

Default Value

The value to use for the “Default Value” extend condition type.