This is a basic web graphics starter project.
It's basically just a copy-paste of the example code for the rotateProjector function, but it's neat!
The box on the left is using "cabinet projection", which is where you don't actually care about perspective, you care about showing parallel lines as parallel. If you've ever had an IKEA flat pack build instruction booklet, that was literally a cabinet assembly booklet, using cabinet projection =D
The box on the right uses "homogeneous coordinate" projection, which is the kind of thing you're used to from real life, as well as video games, 3D modelling software, etc. etc. etc.