Rigid Grid Simulation
This is a simple toy simulation of a grid of point masses connected with rigid rods using Position Based Dynamics (PBD). If you set the drag to 0 and the width of the grid to 1 you can simulate a perfect pendulum of arbitrary length!
You can pan by dragging with your mouse, and zoom by scrolling with your mouse wheel. If you're on a touch device you can pan & zoom in the standard way. The point masses can also be interacted with using the mouse.