Constraints

Currently there are the following constraints:

• Translation
• Rotation
• Scale
• Transform
• Distance

These constraints all work in world space. For example, distance is measured in world space, not local space. So even if an object scales times 2, a distance of 200 pixels is still 200 pixels in world space, not 200 pixels in local space, which would be 400 pixels in world space.

In progress:

• IK constraint

Planned:

• Path constraint

IK constraint

Nomenclature:

• Root: The start of the IK chain
• End effector: The end of the IK chain, which tries to reach the target.
• Target: The point for the end effector to reach.

constraint.ik(target, { 
  algorithm: "ccd",
  depth: 2, 
  strength: 1
});

Parameters:

• algorithm:
  • FABRIK (Forward And Backward Reaching Inverse Kinematics): Fast, but unable to use angle constraints.
  • CCD (Cyclic Coordinate Descent): Slower, but can use angle constraints.
• depth: Defines the actual IK chain. A depth of 2 means that the chain root is two parents from the end effector.

Angle constraints can be set (if using CCD) using a bone component.

bone({ minAngle: -180, maxAngle: 180 });

Path constraint

constraint.path(path, {
  distance: 0,
  offset: vec2(50, 50),
  followMotion: true,
  strength: 1
});