My final project was a cloth simulation with implicit Euler generated by OpenGL. I created a cloth pinned in two corners interacting with a moving sphere. To create the animation, I totally the forces due to gravity and due to springs between particles that compose the cloth.
Size: 10x10 pixels
shift + click and drag: translate
control + click and drag: scale
click and drag: rotate
Implementing animation is more complex than it appears.
When using base code, data structures can be challenging to understand.