This is an example of how a Croquet app can call on the services of a rich, independently developed JavaScript library - in this case, Three.js for 3D rendering through WebGL. The example extends into the third dimension the kind of simulation shown in the Simple Animation tutorial: in this case, balls bounce off the (invisible) walls of a container, and off a sphere that's embedded in the container's far wall. Dragging the sphere moves it, constrained to the container bounds. Clicking on the sphere resets the balls' positions to the sphere's center. – https://croquet.studio/docs/croquet/tutorial-1_5_3d_animation.html