Unity 5.x Cookbook

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Creating a simple 2D mini-game – SpaceGirl

This recipe presents the steps to create the 2DSpaceGirl mini-game, on which all the recipes of this chapter are based.

Getting ready

For this recipe, we have prepared the images you need in a folder named Sprites in the 1362_02_01 folder. We have also provided the completed game as a Unity package in this folder named Simple2DGame_SpaceGirl.

How to do it...

To create the simple 2D mini-game Space Girl follow these steps:

Create a new, empty 2D project.
Import supplied folder Sprites into your project.
Convert each sprite image to be of type Sprite (2D and UI). To do this, select the sprite in the Project panel, then, in the Inspector, change choose Sprite (2D and UI) from the drop-down menu Texture Type, and click on the Apply button, as shown in the following screenshot:
Set the Unity Player screen size to 800 x 600: choose the Edit | Project Settings | Player menu, then for option Resolution and Presentation uncheck Default is Full Screen, and set the width to 800 and height to 600, as shown in the following screenshot:
Select the Game panel; if not already chosen, then choose Standalone (800 x 600) from the drop-down menu, as shown in the following screenshot:
Display the Tags & Layers properties for the current Unity project. Choose menu Edit | Project Settings | Tags and Layers. Alternatively, if you are already editing a GameObject, then you can select the Add Layer… menu from the Layer drop-down menu at the top of the Inspector panel, as shown in the following screenshot:
The Inspector should now being displaying the Tags & Layers properties for the current Unity project. Use the expand/contract triangle tools to contract Tags and Layers, and to expand Sorting Layers.
Use the plus sign + button to add two new sorting layers, as shown in the following screenshot: first, add one named Background, and next, add one named Foreground. The sequence is important, since Unity will draw items in layers further down this list on top of items earlier in the list.
Drag the sprite background-blue from the Project panel (folder Sprites) into either the Game or Hierarchy panel to create a GameObject for the current scene.
Set the Sorting Layer of GameObject background-blue to Background (in the Sprite Renderer component).
Drag sprite star from the Project panel (folder Sprites) into either the Game or Hierarchy panel to create a GameObject for the current scene.
In the Inspector panel, add a new tag Star by selecting the Add Tag… option from the Tag drop-down menu at the top of the Inspector panel, as shown in the following screenshot:
Apply the Star tag to GameObject star in the Hierarchy scene.
Set the Sorting Layer of GameObject star to Foreground (in the Sprite Renderer component).
Add to GameObject star a Box Collider 2D (Add Component | Physics 2D | Box Collider 2D) and check its Is Trigger, as shown in the following screenshot:
Drag sprite girl1 from the Project panel (folder Sprites) into either the Game or Hierarchy panel to create a GameObject for the player's character in the current scene. Rename this GameObject player-SpaceGirl.
Set the Sorting Layer of GameObject player-SpaceGirl to Foreground (in the Sprite Renderer component).
Add to GameObject player-SpaceGirl a Box Collider 2D (Add Component | Physics 2D | Box Collider 2D).
Add to GameObject player-SpaceGirl a RigidBody 2D (Add Component | Physics 2D | Rigid Body 2D). Set its Gravity Scale to zero (so it isn't falling down the screen due to simulated gravity), as shown in the following screenshot:
Create a new folder for your scripts named Scripts.

Create the following C# Script PlayerMove (in folder Scripts) and add an instance as a component to GameObject player-SpaceGirl in the Hierarchy:

using UnityEngine;
using System.Collections;

public class PlayerMove : MonoBehaviour {
  public float speed = 10;
  private Rigidbody2D rigidBody2D;

  void Awake(){
    rigidBody2D = GetComponent<Rigidbody2D>();
  }

  void FixedUpdate(){
    float xMove = Input.GetAxis("Horizontal");
    float yMove = Input.GetAxis("Vertical");

    float xSpeed = xMove * speed;
    float ySpeed = yMove * speed;
    
    Vector2 newVelocity = new Vector2(xSpeed, ySpeed);
    
    rigidBody2D.velocity = newVelocity;
  }
}

Save the scene (name it Main Scene and save it into a new folder named Scenes).

How it works...

You have created a player character in the scene, with its movement scripted component PlayerMove. You have also created a star GameObject (a pickup), tagged Star and with a 2D box collider that will trigger a collision when the player's character hits it. When you run the game, the player-SpaceGirl character should move around using the W A S D, arrow keys, or joystick. Currently, nothing will happen if the player-SpaceGirl character hits a star since that has yet to be scripted.

You have added a background (GameObject background-blue) to the scene, which will be behind everything since it is in the rearmost sorting layer Background. Items you want to appear in front of this background (the player's character and the star so far) are placed on sorting layer Foreground. Learn more about Unity tags and layers at http://docs.unity3d.com/Manual/class-TagManager.html.

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