On this tab, you'll find settings that control the behavior of the selected joint(s) in conjunction with the IK tag. Although you can set up inverse kinematics in the IK tag without using the settings here, the tab lets you set the behavior precisely for each individual joint in the IK chain.
Defines how strongly each joint is affected by the IK. The value is usually set to 100% for all joints in the IK chain. If you lower the value for a particular joint in the chain, the joint is more hesitant in following the IK target; the other joints rotate more than this joint in order to reach the chain's target.
If you set the value to 0%, the selected joint is excluded completely from the inverse kinematics and stays in its starting position.
If stretching is switched on for the IK chain in the IK tag, here you can set the stretchiness of the selected joint's bone. The default value of 100% means that the bones each stretch by the same amount if stretching is switched on in the IK tag.
Lowering the value makes the selected joint's bone less stretchy. If you set the value to 0%, the bone won't stretch at all.
In order to understand preferred angles, you first need to understand how the IK tag works. Each IK solver needs as its starting point the coordinates of all objects in the IK chain before the IK takes effect in order to calculate the IK. For the IK tag, this means the coordinates before the IK has been calculated. This ensures the IK is stable, in other words, that you get the same result each time you use the same starting position and target position.
Also, it's not just the IK tag that can change the coordinates of the objects involved in the IK chain. If you manually change a joint object's coordinates, this changes the result of the IK calculation, which is usually what you want. Or perhaps there are expressions besides the IK tag that affect the coordinates of the joints in the IK chain, or keyframes that change the coordinates of the joints over time. You can prevent changes such as these from altering the result of the IK calculation by using the Preferred settings to save the current coordinates as the ending position for the IK calculation. Note that in order for these values to be used, the IK tag's Preferred Rot value must be set appropriately.
Important: Due to the operating principles of 2D IK its rotation angle will already be limited. Here you can only limit the degree to which a Joint Object can bend or stretch. These limits will be defined using the Min R.H. and Max. R.H. settings, regardless of the axis along which the Joint Object is oriented or along which axis it actually bends.
Let’s say you have a 2D chain consisting of three joints. We will concentrate on the center joint that will bend. The initial rotation angle for the IK (the angle at the time the IK tag was added and Preferred Group was applied) was H=0°, P=40° and B=0°. If you move your IK target only the P-value will change. The chain will be bent along this axis. Now set Min. R.H. to -10° and Max. R.H. to 10°. When animated, the Joint Object will only bend to a P-value between 30° (i.e. 40°-10°) and 50° (i.e. 40°+10°).
Defines whether the preferred angles are evaluated for the selected joint object (provided preferred angles are switched on in the IK tag).
Sets the selected joints current rotation as its preferred angle. It doesn't matter how the joint got its current rotation, whether rotated manually or by an expression or by keyframe animation.
Defines how strongly the preferred angle values influence the result of the IK calculation for the selected joint.
Here you can enter the preferred value for H, P and B.
Here you can enter limits for each of the joint‘s angles. When the IK is solved, the joint's angles are not allowed to exceed or fall below these limits. Normally there's no need to set limits for organic characters, but limits can be useful for mechanical animation such as IK on a robot. Note that these limits will only have an effect if the IK Solver is set to 3D in the IK tag.
The values entered are relative to the ending pose for the IK solver. For example, if Min R.P is set to -5°, Max R.P is set to 25° and the selected joint object's ending value for P is 10°, the selected joint object can only move within the range 5° to 35°.
Defines how strongly the limits are factored into the result of the IK calculation.
Toggles the H, P, or B angle limit on and off.
Here you can enter the minimum and maximum limits for each angle.
Here you can enter the lower and upper limits for each angle.