GameObjects

What are GameObjects?

Every object in your game is a GameObject. However, GameObjects don't do anything on their own. They need special properties before they can become a character, an environment, or a special effect. But every one of these objects does so many different things. If every object is a GameObject, how do we differentiate an interactive power-up object from a static room? What makes these GameObjects different from each other?

The answer to this question is that GameObjects are containers. They are empty boxes which can hold the different pieces that make up a lightmapped island or a physics-driven car. So to really understand GameObjects, you have to understand these pieces; they are called Components. Depending on what kind of object you want to create, you will add different combinations of Components to the GameObject. Think of a GameObject as an empty cooking pot, and Components as different ingredients that make up your recipe of gameplay. You can also make your own Components using Scripts.

 

The GameObject-Component Relationship

As described on the GameObjects page, a GameObject contains Components. We'll explore this relationship by discussing a GameObject and its most common Component -- the Transform Component. With any Unity Scene open, create a new GameObject (using Shift-Control-N on Windows or Shift-Command-N on Mac), select it and take a look at the Inspector.

The Inspector of an Empty GameObject

Notice that an empty GameObject still contains a Name, a Tag, and a Layer. Every GameObject also contains a Transform Component.

The Transform Component

It is impossible to create a GameObject in Unity without a Transform Component. The Transform Component is one of the most important Components, since all of the GameObject's Transform properties are enabled by its use of this Component. It defines the GameObject's position, rotation, and scale in the game world/Scene View. If a GameObject did not have a Transform Component, it would be nothing more than some information in the computer's memory. It effectively would not exist in the world.

The Transform Component also enables a concept called Parenting, which is utilized through the Unity Editor and is a critical part of working with GameObjects. If you would like to learn more about the Transform Component and Parenting, please read the Transform Component Reference page.

Other Components

The Transform Component just happens to be critical to all GameObjects, so each GameObject has one. But GameObjects can contain other Components as well.

The Main Camera, added to each scene by default

Taking a look at the Main Camera GameObject, we can see that it contains a different collection of Components. Specifically, a Camera Component, a GUILayer, a Flare Layer, and an Audio Listener. All of these Components provide additional functionality to the GameObject. Without them, there would be nothing rendering the graphics of the game for the person playing! Rigidbodies, Colliders, Particles, and Audio are all different Components (or combinations thereof) that can be added to any given GameObject.