Implementing a Double Jump - Unity Game Development Tutorial

-
Implementing a double jump Unity game development tutorial

In this Unity game development tutorial we'll be looking at how to make a game character do a double jump.

We're going to start with the project we created in our 'Controlling a Character' Tutorial. For those of you that haven't followed this tutorial, we'll give a quick overview.

We've got our character and a few obstacles for it to interact with.

Character interacting with obstacles

Attached to the character is the following script. 

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public float speed;
    public float rotationAnglePerSecond;
    public float jumpSpeed;

    private CharacterController characterController;
    private float yVelocity;
    private float stepOffset;
 stepOffset;

    void Start()
    {
        characterController = GetComponent<CharacterController>();
        stepOffset = characterController.stepOffset;
    }

    void Update()
    {
        float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");

        Vector3 movementDirection = new Vector3(horizontal, 0, vertical);
        movementDirection.Normalize();

        yVelocity += Physics.gravity.y * Time.deltaTime;

        if (characterController.isGrounded)
        {
            characterController.stepOffset = stepOffset;

            if (Input.GetButtonDown("Jump"))
            {
                yVelocity = jumpSpeed;
            }
            else
            {
                yVelocity = -1.0f;
            }
        }

        else
        {
            characterController.stepOffset = 0;
        }

        Vector3 velocity = movementDirection * speed;
        velocity.y = yVelocity;

        characterController.Move(velocity * Time.deltaTime);

        if (movementDirection != Vector3.zero)
        {
            Quaternion fromRotation = transform.rotation;
            Quaternion toRotation = Quaternion.LookRotation(movementDirection, Vector3.up);
            transform.rotation = Quaternion.RotateTowards(fromRotation, toRotation, rotationAnglePerSecond * Time.deltaTime);
        }
    }
}

This script takes input from the player and uses it to move the character accordingly. Currently our character can do a single jump. If the player presses the jump button while the character is on the ground, the Y velocity of the character is increased to make it rise, and gravity is applied to the character to bring it back down to earth.

If you find any of this unfamiliar I suggest working through our tutorial on 'Controlling a Character'

Now let's edit this script to allow the character to be able to do a double jump.

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public float speed;
    public float rotationAnglePerSecond;
    public float jumpSpeed;
    public float doubleJumpSpeed;

    private CharacterController characterController;
    private float yVelocity;
    private float stepOffset;
    private bool jumping;

    void Start()
    {
        characterController = GetComponent<CharacterController>();
        stepOffset = characterController.stepOffset;
    }

    void Update()
    {
        float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");

        Vector3 movementDirection = new Vector3(horizontal, 0, vertical);
        movementDirection.Normalize();

        yVelocity += Physics.gravity.y * Time.deltaTime;

        if (characterController.isGrounded)
        {
            jumping = false;

            characterController.stepOffset = stepOffset;

            if (Input.GetButtonDown("Jump"))
            {
                yVelocity = jumpSpeed;
                jumping = true;
            }
            else
            {
                yVelocity = -1.0f;
            }
        }
        else
        {
            characterController.stepOffset = 0;

            if (jumping && Input.GetButtonDown("Jump"))
            {
                yVelocity = doubleJumpSpeed;
            }
        }

        Vector3 velocity = movementDirection * speed;
        velocity.y = yVelocity;

        characterController.Move(velocity * Time.deltaTime);

        if (movementDirection != Vector3.zero)
        {
            Quaternion fromRotation = transform.rotation;
            Quaternion toRotation = Quaternion.LookRotation(movementDirection, Vector3.up);
            transform.rotation = Quaternion.RotateTowards(fromRotation, toRotation, rotationAnglePerSecond * Time.deltaTime);
        }
    }
}

The first thing we’ve done is add a public variable to hold the double jump speed. 

We only want the double jump to occur if the player presses the jump button again while the character is jumping, so we've added a private boolean variable to keep track of whether the character is currently jumping. We're setting this to true when the character jumps, and we're setting it to false when the character is on the ground.

We've then added a check to see if the jump button has been pressed again while the character is off the ground and already jumping. If it has, then we add the doubleJumpSpeed to the Y velocity.

We’ll save the script, switch back to Unity and set the double jump speed to 4, which is slightly lower than the original jump speed of 5. 

Setting the double jump speed

If we play the game now we can press the space bar to make the character jump, and if we press it again we’ll get a double jump.

There’s a problem though. There’s currently no limit to the amount of jumps we can do. If we keep hitting the space bar then the character will eventually jump out of sight.

Character double jumping off the screen

Let’s make the following changes to the script to fix this. 

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public float speed;
    public float rotationAnglePerSecond;
    public float jumpSpeed;
    public float doubleJumpSpeed;

    private CharacterController characterController;
    private float yVelocity;
    private float stepOffset;
    private bool jumping;
    private bool doubleJumping;

    void Start()
    {
        characterController = GetComponent<CharacterController>();
        stepOffset = characterController.stepOffset;
    }

    void Update()
    {
        float horizontal = Input.GetAxis("Horizontal");
        float vertical = Input.GetAxis("Vertical");

        Vector3 movementDirection = new Vector3(horizontal, 0, vertical);
        movementDirection.Normalize();

        yVelocity += Physics.gravity.y * Time.deltaTime;

        if (characterController.isGrounded)
        {
            jumping = false;
            doubleJumping = false;

            characterController.stepOffset = stepOffset;

            if (Input.GetButtonDown("Jump"))
            {
                yVelocity = jumpSpeed;
                jumping = true;
            }
            else
            {
                yVelocity = -1.0f;
            }
        }
        else
        {
            characterController.stepOffset = 0;

            if (jumping && doubleJumping == false && Input.GetButtonDown("Jump"))
            {
                yVelocity = doubleJumpSpeed;
                doubleJumping = true;
            }
        }

        Vector3 velocity = movementDirection * speed;
        velocity.y = yVelocity;

        characterController.Move(velocity * Time.deltaTime);

        if (movementDirection != Vector3.zero)
        {
            Quaternion fromRotation = transform.rotation;
            Quaternion toRotation = Quaternion.LookRotation(movementDirection, Vector3.up);
            transform.rotation = Quaternion.RotateTowards(fromRotation, toRotation, rotationAnglePerSecond * Time.deltaTime);
        }
    }
}

We’ve added another boolean variable to keep track of whether our character is currently double jumping. We're setting this to true when the double jump starts, and we're setting it to false when the character is on the ground.

Then we have added another check so that the double jump speed isn’t applied if the character is already double jumping.

If we save the script and try this out again, the character is now limited to a double jump no matter how many times the space bar is pressed.

That covers everything for this tutorial. We hope that you found it useful. Please leave any questions or feedback in the comments below, and don't forget to subscribe to get notified when we publish our next post.

Thanks.

Comments

  1. Ishtiaque_Ahmed1 June 2022 at 16:43

    It'd be really helpful if you could do a double jump tutorial for 3D Platformers as well :)

    ReplyDelete

Post a Comment

Popular posts from this blog

Rotating a Character in the Direction of Movement - Unity Game Development Tutorial

-
Image
In this Unity game development tutorial we're going to look at how we can rotate an object so that it faces the direction it’s moving in. You can either watch the video version below or continue reading for written instructions. Right, let's get started by creating a new 3D project in Unity Hub. We'll add a Plane to represent our floor by clicking the plus button on the Hierarchy and selecting 3D Object->Plane. We'll set the scale of the Plane to ten on the X axis and ten on the Z axis. Next, we'll create a material to change the colour of the floor. To do this, we'll click the plus button on the Project panel and select Material. We'll name this material 'Floor'. We'll then click on the box next to Albedo in the Inspector panel, and choose a green colour.  We can now drag the material on to the Plane to assign it. We now need a character to move around our scene. For this we'll head over to the Asset Store by selecting Window->A
Read more

Changing the Colour of a Material - Unity Game Development Tutorial

-
Image
In this Unity game development tutorial we're going to look at how we can write a script to change the Albedo colour of a material. We’ll cover how to change the colour of all objects with the same material and how to change individual instances. You can either watch the video version below or continue reading for written instructions. Right, let's get started by creating a new 3D project in Unity Hub. We'll add a cube to the scene by clicking the plus button in the hierarchy and selecting 3D Object->Cube. Next, we'll create a material. To do this we’ll click on the plus button on the Project panel and select Material. We’ll name this material 'Cube'. We'll click on this box next to Albedo, and choose a green colour.  We can now drag the material onto the Cube to assign it. Next, we'll add a script to change the colour when the mouse is over the cube. To do this we’ll select the cube in the hierarchy, click on 'Add Component' and search
Read more

Creating Terrain from Heightmaps - Unity Game Development Tutorial

-
Image
In this Unity game development tutorial we're going to look at how we can create realistic looking terrain from real world height data. You can either watch the video version below or continue reading for written instructions. You can hand sculpt terrain using the tools in Unity, but in this tutorial we're going to look at an alternative - using images known as heightmaps. A heightmap is a grayscale image that contains height information. The darker pixels represent areas of low height and the lighter pixels represent higher areas. Below is an example of a heightmap. There are various sources online that you can get free heightmaps, but we're going to look at this one that allows you to create heightmaps of the real world - https://cs.heightmap.skydark.pl/ This resource was created for generating terrain for the game Cities Skylines but it will work just as well in Unity. Basically, it allows us to select any 18km square area on the map and then create a hei
Read more