“Inverse Kinematics is the inverse function/algorithm of Forward Kinematics. The Forward Kinematics function/algorithm takes a target position as the input, and calculates the pose required for the end effector to reach the target position — the pose is the output.” - wikipedia
Inverse kinematics (
IK) is used for rigging things such as arms, legs, robot parts,
heck even car rigs can have IK setups in them.
If you take your hand and pick something up, did you rotate your humerus first… then your radius/ulna next… then your wrist, to get to what you were picking up? Probably not. You just stuck your hand out and grabbed it.
Sure all those
bones rotated and moved… into the position required for you
to pick up the object, but you drove your hand out first to pickup the item
This is the traditional sense of
IK in a nutshell. You take a point at the
end of the chain and you can pull it around, and the IK math solves an
to reach for that point in space, all the while it rotates all the elements
in the chain to obtain the best possible positions to get that
to the point in space that you’re moving around.
Here’s a look at that in Maya.
There are a few ways to approach this. But for now what you see above is
joint chain that has an
IK solver attached to it(because Maya’s native
solver attaches to
joints), but if you wrote your own
IKChain solver you could
have the controls as
inputs to your
node and output the
joints from the
Regardless of HOW you’re being forced to setup
IK the concept of
essentially the same, and once you get a “handle” on it you’ll be setting
IK a lot (or using a tool to do it for you).
Maya has a few flavours of
IK solvers and you’re going to need to do
some study to learn what each do etc;
There is also a splineIK approach that uses a
) to drive the joint chain`.
Here is our Cube (with more
subdivisions to show the
being driven by a
rotatePlane IK Solver in Maya (which makes it act more
like a shoulder
joint at the base, with an elbow break 1/2 way down).