Chapter 5. World Space UI
Graphical user interface (GUI) or just UI, usually refers to on-screen two-dimensional graphics, which overlay the main gameplay and present information to the user with status messages, gauges, and input controls such as menus, buttons, sliders, and so on.
In Unity 5, UI elements always reside on a canvas. The Unity manual quotes the canvas component as the following:
The Canvas component represents the abstract space in which the UI is laid out and rendered. All UI elements must be children of a GameObject that has a Canvas component attached.
In conventional video games, UI objects are usually rendered in a screen space canvas as an overlay. Screen space UI is analogous to a piece of cardboard pasted on your TV or monitor, overlaying the game action behind it.
However, that doesn&apos...