Basic syntax of unity script (3) - accessing game object components

Components belong to game objects , Because all scripts are components , So general scripts can be attached to game objects .

Common components can be obtained through simple member variables

Components	Variable
Transform	transform
Renderer	renderer
Light	collider
Rigidbody	rigidbody
Camera	Camera( Only camera objects are valid )
Animation	animation

The components here are embodied in Property panel On , And the variable is in Script As reflected in .

stay Unity in , Components attached to game objects can be accessed through GetComponent Methods to get , It can be used in this way

Along the x The axis moves in the positive direction 1 A unit of

	void Update () {
    
		transform.Translate(1*Time.deltaTime, 0, 0);
		
		GetComponent<Transform>().Translate(1 * Time.deltaTime, 0, 0);	
	}

transform It's a variable. ,Transform Is a class or script . Case differences enable developers to distinguish variables from class and script names .

It can also be passed GetComponent Method to get other scripts . for example
There is already one HelloWorld class , And there is one in the class **sayHello()** Method

	void Update () {
    
	HelloWorld helloWorld=GetComponent<HelloWorld>();// obtain HelloWorld Script script 
	helloWorld.sayHello();// perform sayHello Method 
	}

How to execute only once in a script Start and Awake in