Using GameObjects and Assets

GameObjects

• Everything within a scene view is called a GameObject.
• Every GameObject have a Transform property
• Components can be added to the GameObjects to modify their properties
• Scripts can also be added to GameObjects as components
• Components can be added, copied or removed using using Inspector cog icon
• Scripts can be added by dragging them to an empty space in the Inspector view or clicking the Add Component button adn choosing New Script
• GameObjects can be parented and the parent child relationship is represented by arrows in the Hierarchy Window.
• GameObjects can selected either in the Hierarchy window or the Scene view

1. GameObjects as seen from the Hierarchy window
2. GameObjects in the Scene Window
3. Components of the Cube GameObject

Working with Prefabs

• Prefabs are pre-configured game objects. You can turn any GameObject from the Scene into a prefab by dragging it into the Project Window.

• Prefabs are saved as files as part of the project.

• Prefabs are used for all sorts of GameObjects, e.g creating projectiles, explosions, enemies, collectables, and many more.

• You can modify the prefab and apply the changes to all the instances of the prefab or revert the changes entirely.

Tags

• Tags are used to identify game objects, e.g we could have many enemies in the game and we can identify them all by tagging them as enemies.

• You can assign an existing tag or create one if it doesn't already exists.

• Tags can used from code. This is very useful especially within the script of a prefab, e.g when an enemy is created, it might need to find the player in the game.

Using Tags in Scripts

// Finding the player from within a script attached to the enemy
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;

public class Enemy : MonoBehaviour
{
    GameObject player;
    NavMeshAgent agent;
    // Start is called before the first frame update
    void Start()
    {
        agent = GetComponent<NavMeshAgent>();
        // Find the player in the game
        player = GameObject.FindGameObjectWithTag("Player");
    }

    // Update is called once per frame
    void Update()
    {
        // set the enemy destinate to player
        agent.SetDestination(player.transform.position);
    }
}

Layers

Layers allow us to define some common functionality across unrelated game objects, e.g we can hide objects in the same layer from the camera, which objects should ignore a Raycast and which object we would like to see in the Scene view.

If the layer is there, we can add a new layer.

Adding a New Layer

• Click the Layer drop down
• Choose Add Layer

or alternatively we can add layers by using the menus byt choosing Edit -> Project Settings -> Tags and Layers

Importing Assets

Working with Sprites