I made two chain animations, to show the difference between Inverse and Forward Kinematics animations. Forward Kinematic animation is just using After Effects to place down keyframes for specific points. You have to animate every joint individually but can use parenting tool to link up layers so they can animate at the same time. Here is the forward chain animation:
Forward Kinematic animation is animation which fills in gaps between point a to point b to make it look natural or more specific and detailed in the animation process. It is harder to set up than Forward Kinematics but is easier and faster to animate when you set up the Inverse Kinematics. Here is the Inverse Kinematic animation:
I started by making the chains in Adobe Photoshop. I created a 1280 (with) by 720 (hight) pixel Photoshop workspace with 72 resolution as After Effect will need to read a lot of pixel information if the resolution as up high like 300 res. I made the chains by using a chain brush which I found online. I placed each of the chains on separate layers so I can be able to move each part of the chains in After Effects and it can read Photoshop layers.
Next I saved and then placed it into a new After Effects project and made a new composition with 1280 pixels (with) by 720 pixels (hight) and name it ‘Forward Chain’. I will start by making the forward kinematic animation. Place the chain .psd file into After Effects composition.
Line each of the chain loops together so it a long linked chain going upwards. For each of the chain rings, move each anchor point at the top of each of the chain layers. Move the chain anchor points by clicking on one layer, then selecting the Pan behind tool at the top of the toolbar.
Now you can move the anchor point freely without mistakenly moving the layer it self.
When you placed the anchor points, start to link each of the chain layers by parenting. Parenting is helpful to link layers so when a linked part is moved they all move with it. We will be parenting the lowest which for me is chain 6 to the highest chain in the composition which is chain 1. Parent by dragging the circle swirl to each of the layers. So if I wanted to link chain 6 to chain 5, I would drag the swirl from chain 6 and drag it to chain 5 to link it up. Do this for all of the chain by bottom to the top (Chain 6 to Chain 1).
We are now ready to animate the chain. We will only need to animate keyframes for rotation as we only need to make a swing chain from left to right till it runs out of speed and goes back to a straight line of chains. Start key framing each of the rotations but making sure each of the chains don’t look out of place by the rotations being too much rotated.