In case you don't know, many people have no idea they are just sleeping. Sometimes dream is so real that people think it's reality.
The movie "Inception" has a decent disscussion about what dream is, but many silly people just think it is fictional!
In the movie, totems are used to determine whether you are in a dream or not.
Do you want to test your "reality"? I have made two totems for you. After 5 seconds, you should see the spinning top falls down and you get a "3" on the die. Otherwise, time to wake up!
The model looks very simple. However, it turns out very complicated to implement, in terms the limitation of "Painter's Algorithm" and using shaders.
Especially to write the correct shader, the order to draw triangles matters. It's a pain to figure out the right way to draw each triangle.