Unity Basic Course: Implementing Jump Feature

In this course, we will learn how to implement the jump feature for 2D or 3D game characters in Unity. Jumping is one of the key elements in a game’s character movement mechanics and can significantly enhance the player’s experience. We will start by implementing a basic jump feature and then proceed to create smoother jumps using the physics engine and animations.

1. Setting Up the Project

To implement the jump feature in Unity, you first need to create a new project. Please follow the steps below to set it up.

1.1 Installing Unity and Creating a New Project

  1. Launch Unity Hub.
  2. Click the ‘New’ button to create a new project.
  3. Select either the 2D or 3D template. This course will use the 3D template.
  4. After setting the project name and save path, click the ‘Create’ button.

1.2 Configuring the Basic Environment

We will create a floor and a character to configure the basic environment.

  • Select 3D Object in the Hierarchy view and choose Cube to create the floor.
  • Adjust the Transform component of the created cube to set the size and position of the floor.
  • Similarly, create a new cube to represent the character and adjust it to an appropriate size.

2. Writing the Jump Script

Now, we will add a C# script to implement the jump feature for the character. Please follow the steps below to write the script.

2.1 Adding the Script

  1. Right-click on the Assets folder in the Project view and select Create > C# Script.
  2. Name the script PlayerController.
  3. Select the character cube in the Hierarchy view, then in the Inspector window, click Add Component and add the PlayerController script.

2.2 Writing the Script Content

Now, open the PlayerController script and write the content below.


using UnityEngine;

public class PlayerController : MonoBehaviour
{
    public float moveSpeed = 5f;
    public float jumpForce = 5f;
    private bool isGrounded;
    private Rigidbody rb;

    void Start()
    {
        rb = GetComponent();
    }

    void Update()
    {
        Move();

        if (Input.GetButtonDown("Jump") && isGrounded)
        {
            Jump();
        }
    }

    void Move()
    {
        float moveHorizontally = Input.GetAxis("Horizontal");
        Vector3 movement = new Vector3(moveHorizontally, 0f, 0f) * moveSpeed * Time.deltaTime;
        transform.position += movement;
    }

    void Jump()
    {
        rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
        isGrounded = false;
    }

    void OnCollisionEnter(Collision collision)
    {
        if (collision.collider.tag == "Ground")
        {
            isGrounded = true;
        }
    }
}

Script Explanation

The script above includes the character’s movement and jump features. Let’s take a look at the principles of each feature:

  • moveSpeed: Adjusts the speed of the character’s movement.
  • jumpForce: Adjusts the force of the character’s jump.
  • isGrounded: Checks whether the character is touching the ground.
  • Rigidbody: Implements jumping using Unity’s physics engine.
  • Move() method: Moves the character horizontally.
  • Jump() method: Performs the jump action.
  • OnCollisionEnter() method: Determines if it has touched the ground.

3. Applying the Physics Engine

To utilize the physics engine effectively in Unity, you need to add Rigidbody and Box Collider components to both the character and the floor cube.

3.1 Adding Rigidbody Component

  1. Select the character cube and click the Add Component button.
  2. Search for and add Rigidbody.
  3. Now add a Box Collider to the floor cube in the same way.

3.2 Adjusting Jump Physics

Try adjusting the Mass and Drag values of the Rigidbody. This allows you to select the character’s weight during jumps and the resistance experienced in the air.

Tip: If you want to modify the physical movement, try adjusting the Gravity Scale value of the Rigidbody. Setting it too low can cause unnatural movements during jumps.

4. Adding Jump Animation

Adding an animation when the character jumps makes the visuals more appealing. Let’s follow the steps below to set up the jump animation.

4.1 Creating and Setting Animation Clip

  1. In the Project view, select Right Click > Create > Animation to create a new animation clip. Name it JumpAnimation.
  2. Open the Animation window, select the character cube, and add the animation you will use to the clip.

4.2 Setting Up Animator

Now we will set up the Animator to play the jump animation based on the character’s state:

  1. In the Project view, select Right Click > Create > Animator Controller. Name it PlayerAnimator.
  2. Add the Animator Controller to the main character cube.
  3. Open the Animator and drag the JumpAnimation clip to add it to the state.

4.3 Adding Animation Trigger


void Jump()
{
    rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
    isGrounded = false;
    animator.SetTrigger("Jump");
}

5. Testing and Debugging

Now that all settings are complete, click the Play button to test the game. Check whether the jump function operates correctly, whether the jump animation plays smoothly, and whether the character makes contact with the ground.

5.1 Debugging Tips

  • If the character does not jump because it is not in contact with the ground, check whether the Is Kinematic property of the Rigidbody is checked.
  • If the animation does not play, verify that the animator’s trigger is set correctly.

6. Conclusion

In this course, you learned how to implement the jump feature for a character in Unity. We also explored how to enhance the jump feature with the physics engine and animation settings. Moving forward, consider adding various movement features or attempting more complex physical effects. Unity is a highly flexible engine, so keep trying new features and create your own game.

7. Additional Learning Resources

If you want to learn more advanced topics, we recommend the following resources: