Tag Archives: control

Controlling 2D player animations with C# code in Unity

In this tutorial, you will learn how to control player animations in your 2D game with C# code in Unity. Watch the video below and then scroll down for the sample code.

Sample code

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour {

  public float speed = 5f;
  public float jumpSpeed = 8f;
  private float movement = 0f;
  private Rigidbody2D rigidBody;
  public Transform groundCheckPoint;
  public float groundCheckRadius;
  public LayerMask groundLayer;
  private bool isTouchingGround;
  private Animator playerAnimation;

  // Use this for initialization
  void Start () {
    rigidBody = GetComponent<Rigidbody2D> ();
    playerAnimation = GetComponent<Animator> ();
  }
  
  // Update is called once per frame
  void Update () {
    isTouchingGround = Physics2D.OverlapCircle (groundCheckPoint.position, groundCheckRadius, groundLayer);
    movement = Input.GetAxis ("Horizontal");
    if (movement > 0f) {
      rigidBody.velocity = new Vector2 (movement * speed, rigidBody.velocity.y);
    }
    else if (movement < 0f) {
      rigidBody.velocity = new Vector2 (movement * speed, rigidBody.velocity.y);
    } 
    else {
      rigidBody.velocity = new Vector2 (0,rigidBody.velocity.y);
    }

    if(Input.GetButtonDown ("Jump") && isTouchingGround){
      rigidBody.velocity = new Vector2(rigidBody.velocity.x,jumpSpeed);
    }

    playerAnimation.SetFloat ("Speed", Mathf.Abs (rigidBody.velocity.x));
    playerAnimation.SetBool ("OnGround", isTouchingGround);
  }
}

Next tutorial:  Flipping the player with code

Introduction to C# scripting & collision detection for 2D games in Unity

This video gives an introduction to writing code for 2D games in Unity using the C# programming language. We’ll get started by adding collision detection so that our player object (or character) can collect points when colliding with coins in the game. You’ll learn how to setup 2D collision detection, increase a score variable, display messages in the console to test your code, and how to destroy objects (or make objects disappear) in a scene using code.

Watch the video below and scroll down to see the sample code.

Sample code

using UnityEngine;
using System.Collections;

public class CoinScript : MonoBehaviour {

  public int score = 0;

  // Use this for initialization
  void Start () {
  
  }
  
  // Update is called once per frame
  void Update () {
  
  }

  void OnTriggerEnter2D(Collider2D other){
    Destroy (gameObject);
    score++;
    Debug.Log ("Score: " + score);
  }
}

Next tutorial: Moving the player with C# code

Moving an object with force in PlayCanvas

This tutorial explains how to use keyboard input to move an object around. But rather than telling the object how far it needs to move (like in this other tutorial), we will apply force to the object instead. This means that the object your moving can also hit other objects and interact with them rather than just going through them.

Step 1 – Setting up the object you want to move

To begin with, you need to create an object or use a model that you want to move. Then you need to add a Rigid Body component and a Collision component so that this object can collide and interact with other objects in the scene. For this example, I have added a Box entity (click + in the Hierarchy and then click Box) but you can use another 3D shape or model.

3dobject
Then you need to select the object and click on Add Component (in the Inspector panel on the left side of the screen) and choose the Collision component. If you have a box shape (entity) then you should set the Collision Type to Box (if you have a sphere shape, then select Sphere for Type, and so on).

Match your collision settings up so they look like the settings shown below. The numbers in the Half Extents property boxes should be half the numbers in the Scale property boxes above it. Eg. if the scale X property of the box has a value of 4 then the Half Extents X value should be 2.

box_collision

Now click on Add Component again and this time add the Rigid Body component. Change the Type to Dynamic and modify the values so they are the same as those below (experiment with these values later to get the effect you want).

rigid_body
It is important to make sure any other objects that this object will interact with also have Rigid Body and Collision components attached to them. For example, if you don’t want this object to fall through your ground in the scene, then the ground object should have a Static type Rigid Body and a Collision component.

If you want other objects to not be moved by this object, they should have a Static type Rigid Body and Collision component. Otherwise, if you want this object to move other objects when it touches them, add Dynamic type Rigid Body and Collision components to those other objects.

Adding a script to the object

Click on + in the Assets panel and choose Script to create a new script.

create_script
Call the new script moveWithForce.js and hit Enter to create the script.

script_name

Now you need to attach the script to the 3D object or model you want to move or control. Select the 3D object (eg. box) and then click on Add Component and select Script. Drag the moveWithForce.js script onto the Scripts component on the object in the Inspector panel and then let go. The script should now be attached to the object.

script_attached

 

Writing the code

Double-click on the moveWithForce.js script you just created in the Assets panel and replace all of the existing code with the following code in the Code Editor window:

// Add this code to any object you want to move with force
// Object that this script is attached to must have collision component and DYNAMIC rigid body component

pc.script.attribute("power", "number", 1000);  // set power to initial value of 1000
pc.script.create('moveWithForce', function (app) {
    // create force variable
    var force = new pc.Vec3();
    // Creates a new MoveWithForce instance
    var MoveWithForce = function (entity) {
        this.entity = entity;
    };

    MoveWithForce.prototype = {
        // Called once after all resources are loaded and before the first update
        initialize: function () {
            // Check for required components
            if (!this.entity.collision) {
                console.error("First Person Movement script needs to have a 'collision' component");
            }
            
            if (!this.entity.rigidbody || this.entity.rigidbody.type !== pc.BODYTYPE_DYNAMIC) {
                console.error("First Person Movement script needs to have a DYNAMIC 'rigidbody' component");
            }
            
            // Listen for keyboard press events
            app.keyboard.on(pc.EVENT_KEYDOWN, this._onKeyDown, this);
        },

        // Called every frame, dt is time in seconds since last update
        update: function (dt) {

            // movement
            var x = 0;
            var z = 0;
            var y = 0;
            
            // Use W-A-S-D keys to move player around and Space to make player jump
            // Check for key presses
            if (app.keyboard.isPressed(pc.KEY_LEFT)) {
                x -= 0.01;
            }
            
            if (app.keyboard.isPressed(pc.KEY_RIGHT)) {
                x += 0.01;
            }
            
            if (app.keyboard.isPressed(pc.KEY_UP)) {
                z -= 0.01;
            }
            
            if (app.keyboard.isPressed(pc.KEY_DOWN)) {
                z += 0.01;
            }
            
            if (app.keyboard.isPressed(pc.KEY_SPACE)) {
                console.log("space pressed");
                y += 0.05;
            }
            
            // use direction from keypresses to apply a force to the character (x and z axes)
            if (z !== 0) {
                force.set(0, 0, z).normalize().scale(this.power);
                this.entity.rigidbody.applyForce(force);
            }
            
            if (x !== 0) {
                force.set(x, 0, 0).normalize().scale(this.power);
                this.entity.rigidbody.applyForce(force);
            }
            
            // use direction from keypresses to apply a force to the character (y axis)
            if (y !== 0) {
                force.set(x, y, z).normalize().scale(this.power);
                this.entity.rigidbody.applyForce(force);
            }
        },
        
        _onKeyDown: function (event) {
            // When the space bar is pressed this scrolls the window.
            // Calling preventDefault() on the original browser event stops this.
            event.event.preventDefault();
            console.log("Scrolling disabled");
        }
    };

    return MoveWithForce;
});

Now click on Save and then go back to the game Editor window. That’s it! Launch your game by clicking on the Launch (play) button and you should now be able to control the 3D object/model by using the keyboard to move it around and make it jump. The code is set up to move the object using the arrow keys and space bar to jump. However, you can change these keys and you can also remove the code that makes the object jump if you don’t want to make it jump in the game.

 

 

 

Controlling audio with scripts

This tutorial explains how to control the audio in your game using scripts. You can play, stop, pause and resume sound effects and songs in your game when certain events occur by controlling the sound with code. This video explains how to do that and if you scroll down you will find the sample code.

The following sample code is used to control an audio source/slot called “song” that is attached to the same entity that the script is attached to. The filename of this script is playsong.js.

pc.script.create('playsound', function (app) {
    // Creates a new Playsound instance
    var Playsound = function (entity) {
        this.entity = entity;
    };

    Playsound.prototype = {
        // Called once after all resources are loaded and before the first update
        initialize: function () {
        },

        // Called every frame, dt is time in seconds since last update
        update: function (dt) {
            if(app.keyboard.wasPressed(pc.input.KEY_P)){
                this.entity.sound.play('song');
            }
            
            if(app.keyboard.wasPressed(pc.input.KEY_S)){
                this.entity.sound.stop('song');
            }
        }
    };

    return Playsound;
});

The following sample code is used to control an audio source/slot called “song” that is attached to a Sound entity called “mySound“. The script can be attached to any other entity in the game scene. The filename of this script is playsong.js.

pc.script.create('playsound', function (app) {
    // Creates a new Playsound instance
    var Playsound = function (entity) {
        this.entity = entity;
    };

    Playsound.prototype = {
        // Called once after all resources are loaded and before the first update
        initialize: function () {
        },

        // Called every frame, dt is time in seconds since last update
        update: function (dt) {
            // creates variable for audio entity
            var AudioEntity = app.root.findByName('mySound');
            if(app.keyboard.wasPressed(pc.input.KEY_P)){
                AudioEntity.sound.play('song');
            }
            
            if(app.keyboard.wasPressed(pc.input.KEY_S)){
                AudioEntity.sound.stop('song');
            }
        }
    };

    return Playsound;
});

South Of The Border by Audionautix is licensed under a Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/)
Artist: http://audionautix.com/

Transforming objects using scripts

This video tutorial will show you how to transform objects (move, rotate, scale) in your Unity game using C# scripts and also how to implement player interaction with the game by allowing players to transform objects using keypresses on their keyboard.

Watch the video below and then scroll down to see the sample code.

Here is some sample code with different object transformations assigned to different keypresses on the keyboard. You can change the transformations and assigned keys although it is a good idea to use the input manager rather than specific keypress detection so that your players have the option of remapping keys to suit their own preferences.

using UnityEngine;
using System.Collections;
 
public class move : MonoBehaviour {
 
 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
 if (Input.GetKey (KeyCode.W)) {
 transform.Translate (0f,0f,0.1f);
 }
 if (Input.GetKey (KeyCode.S)) {
 transform.Translate (0f,0f,-0.1f);
 }
 
 if (Input.GetKey (KeyCode.D)) {
 transform.Translate (0.1f,0f,0f);
 }
 if (Input.GetKey (KeyCode.A)) {
 transform.Translate (-0.1f,0f,0f);
 }
 
 if (Input.GetKey (KeyCode.Z)) {
 transform.Rotate (0f,1f,0f);
 }
 
 if (Input.GetKey (KeyCode.X)) {
 transform.Rotate (0f,-1f,0f);
 }
 
 if (Input.GetKey (KeyCode.C)) {
 transform.localScale = new Vector3(1f,1f,1f);
 }
 
 if (Input.GetKey (KeyCode.V)) {
 transform.localScale = new Vector3(5f,5f,5f);
 }
 
 }
}

Note: If you find that the values for x, y and z axes seem to work the opposite to what you expect, it might be because you have the camera at a different angle. For example, if your camera is on the opposite side of your object, then pressing the key that is meant to move the object left might actually move it to the right.

Now try using variables to store the values for speed, eg:

using UnityEngine;
using System.Collections;
 
public class move : MonoBehaviour {
 
 public float turnSpeed = 5.0f;
 public float forwardSpeed = 0.25f;
 
 // Update is called once per frame
 void Update () {
 transform.Rotate(turnSpeed, 0.0f, 0.0f);
 transform.Translate(0.0f, 0.0f, forwardSpeed);
 }
}

Here is another method of moving objects on their own at a steady speed (this example does not include keyboard input).

using UnityEngine;
using System.Collections;
 
public class moveCube : MonoBehaviour {
 
 public float speed = 1.0f;
 
 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
 transform.Translate (Vector3.forward * speed * Time.deltaTime);
 // This will move the cube forward on its own at steady speed
 // Vector3 is for 3D , Vector2 is for 2D
 // You can change Vector3.forward to Vector3.back, Vector3.left, or Vector3.right
 
 
 }
}

Keyboard input in Unity

In Unity, you can set up your game to detect specific keypresses and then react to those keypresses. However, there is a better way of setting up input using Unity’s built-in Input Manager.

The video below will show how to use the Input Manager and how to also detect specific keypresses in your game. After you’ve finished watching the video, scroll down to see the sample code.

Input Manager

Setting up your game to detect specific keypresses doesn’t allow players to remap the game input controls to suit their preferences. However, if you use the Input Manager you can allow the player to map the controls to their own liking or use the defaults (eg. the W, A, S and D keys).

You can set up controls for each of the different axes in the Input Manager by clicking Edit > Project Settings > Input. Then you can write a script using the GetAxis() method to detect key presses.

Below is some sample code that will display horizontal and vertical movement in the console when the W, A, S and D keys (or arrow keys) are pressed. Simply place this code inside the Update() method in a script that is attached to an object inside your game’s scene (eg. the Main Camera object).

float horizontalValue = Input.GetAxis("Horizontal");
float verticalValue = Input.GetAxis("Vertical");
 
if (horizontalValue != 0)
{
 print("Horizontal movement: " + horizontalValue);
}
 
if(verticalValue != 0)
{
 print("Vertical movement: " + verticalValue);
}

Save the script and then run the scene. Check the output in the console after pressing the W, A, S and D keys and the arrow keys.

Try out the code above and see what happens when you press the W, A, S and D keys or arrows keys on your keyboard. Also, did you notice how the sentences and values are combined in the print statements above? This is an example of concatenation (where strings are joined together).

Specific key input

Although it is generally a good idea to use the Input Manager for key input detection, it may sometimes be necessary to check whether a specific key has been pressed by the user. To do this, you can use the GetKey() method. This method will read a keycode which corresponds to a specific key on the keyboard. It will then return either a true or false value depending on whether the key is pressed or not.

As an example, to check if the A key is being pressed, you can use the following code. Just place this code inside the Update() method in a script that is attached to an object inside your game’s scene (eg. the Main Camera object).

bool isKeyDown = Input.GetKey(KeyCode.A);

Tip: In MonoDevelop, if you are not sure what keycode corresponds to a key, you can begin typing in the name of the KeyCode object followed by a period. A popup menu should appear, showing you all of the possible choices. This automatic popup feature in MonoDevelop can be used for many other objects/methods too and is pretty handy.

You can use a simple if statement to specify an action to occur when a keypress is detected. For example, the following code will output a message to the console saying that the ‘A’ key has been pressed when it is detected that the ‘A’ key has been pressed.

if(Input.GetKey(KeyCode.A))
{
 print("You pressed the 'A' key.");
}

Save the script and then run the scene. Check the output in the console after pressing the ‘A’ key.