Ground Check Unity: Best Step-By-Step Guide

Ground check unity can be easily implemented in Unity, which is a common assertion, but properly understanding this seemingly simple mechanism may elevate your platformer to a delight to play. While the basic implementation is simple, creating a strong and subtle ground check is the secret sauce for responsive jumps and smooth player movement. Fear not, intrepid developer; in this guide, we’ll delve deeply into the BoxCast technique, a great tool for ensuring your players always have solid ground beneath their feet.

ground check unity

Setting up Ground Check In Unity

1. Create a New Layer for the Ground Tilemap

Begin by organizing your scene. Create a new layer specifically for the ground tilemap. Assign this layer to all the tiles that represent the ground in your level.

Click on the add layer in the inspector:

click on add layer

And then create a new layer by writing the name of the new layer on an empty slot:

Write name of new layer

2. Define Box Collider Variable

In your script, create a variable of type BoxCollider2D. This variable will be assigned the Box Collider component attached to the player character in the Start method.

private BoxCollider2D boxColl;

void Start()
{
    boxColl = GetComponent<BoxCollider2D>();
}

3. Implement a LayerMask Variable

Next, declare a variable of type LayerMask named “groundLayer.” This variable will be used to filter the objects the BoxCast should interact with, ensuring it only detects the ground layer.

[SerializeField] private LayerMask groundLayer; 

4. Create the IsGrounded Function

Now, implement a function named “IsGrounded” with a return type of boolean. This function will use Physics2D.BoxCast to ground check in unity.

bool IsGrounded()
{
    return Physics2D.BoxCast(boxColl.bounds.center, boxColl.bounds.size, 0f, Vector2.down, 0.1f, groundLayer);
}

The parameters of the BoxCast are as follows:

  • Origin (boxColl.bounds.center): The center point of the BoxCollider.
  • Size (boxColl.bounds.size): The size of the BoxCollider.
  • Rotation (0f): The rotation of the BoxCollider.
  • Direction (Vector2.down): The direction of the cast, in this case, downwards.
  • Distance (0.1f): The maximum distance for the cast.
  • Layer Mask (groundLayer): The layer mask specifying which layers to include in the cast.

Click here To Learn More About BoxCast Function:

5. Integrate Ground Check in Jumping Mechanism

Incorporate the ground check into your jumping logic. Modify the jump statement to include a check for whether the player is grounded using the IsGrounded function.

if (Input.GetButtonDown("Jump") && IsGrounded())
{
    rb.velocity = new Vector2(rb.velocity.x, jumpHeight);
}

6. Assign the Ground Layer in Inspector

In the Unity Inspector, assign the newly created ground layer to the player character’s script. This step ensures that the BoxCast only interacts with objects on the designated ground layer.

Click here to learn to make terrain using Tilemap in Unity:

assign the ground layer to the timemap Terrain

7. Test and Debug

Finally, play your scene and check for any errors. Ensure that the ground check is functioning as expected, allowing the player to jump only when grounded.

Click Here To Create A Basic Player Controller For 2D Platformer:

Full Code With Movement Controller:

Below is attached the full code of the player character with all the movement animations and the ground check unity implemented.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour
{
    [SerializeField] private float speed = 5f;
    [SerializeField] private float jumpHeight = 10f;
    [SerializeField] private float gravity = 3f;
    [SerializeField] private LayerMask groundLayer;

    private Rigidbody2D rb;
    
    private Animator animator;
    private SpriteRenderer spriteRenderer;
    private float horizontalInput;
    private BoxCollider2D boxColl;

    private enum MovementState {idle, running, jumping, falling};
    private MovementState state;


    


    void Start()
    {
        boxColl = GetComponent<BoxCollider2D>();
        animator = GetComponent<Animator>();
        rb = GetComponent<Rigidbody2D>();
        rb.gravityScale = gravity;
        spriteRenderer = GetComponent<SpriteRenderer>();
}

    void Update()
    {
        if (Input.GetButtonDown("Jump") && isGrounded())
        {
            rb.velocity = new Vector2(rb.velocity.x, jumpHeight);
        }

        horizontalInput = Input.GetAxisRaw("Horizontal");

        rb.velocity = new Vector2(speed * horizontalInput, rb.velocity.y);
        AnimatePlayer();

    }

    void AnimatePlayer()
    {
        MovementState state;

        if (horizontalInput > 0)
        {
            state = MovementState.running;
            spriteRenderer.flipX = false;
        }
        else if (horizontalInput < 0)
        {
            state = MovementState.running;
            spriteRenderer.flipX = true;
        }
        else
        {
            
            state = MovementState.idle;
        }

        if(rb.velocity.y > .1f)
        {
            state = MovementState.jumping;
        }
        else if(rb.velocity.y < -.1f)
        {
            state = MovementState.falling;
        }

        animator.SetInteger("state", (int)state);
    }

    private bool isGrounded()
    {
        return Physics2D.BoxCast(boxColl.bounds.center, boxColl.bounds.size, 0f, Vector2.down, 0.1f, groundLayer);
    }
}


You Might Ask:

What is a ground check in Unity platformers?

A ground check is a basic but important mechanism ensuring precise player interactions, especially during jumps, by detecting if the player is on the ground.

Why is a ground check important in Unity game development?

A ground check ensures accurate jumping mechanics, preventing unintended mid-air actions and contributing to a more responsive gameplay experience.

How does the BoxCast method contribute to ground checking?

The BoxCast method in Unity enables developers to cast a box-shaped ray in a specified direction, allowing for efficient detection of ground surfaces and ensuring reliable ground checks.

What role does the LayerMask play in the ground check process?

The LayerMask filters the objects the BoxCast interacts with, ensuring that the ground check focuses exclusively on desired layers, such as the layer assigned to the ground tilemap.

Can the ground check be customized for different game scenarios?

Yes, the ground check parameters, such as box size, cast distance, and layer assignment, can be adjusted to suit the specific requirements of different Unity 2D platformer projects.

How can I troubleshoot and ensure my ground check is working correctly?

To verify the ground check, playtest the game and monitor for any unexpected behaviors. Additionally, ensure that the ground layer is correctly assigned in the Unity Inspector and that the BoxCast parameters align with your game’s needs.

How to check if player is grounded?

You can check if player is grounded by using the Boxcast function which makes an invisible box where you specify, and if the box collides with something beneath then the player is grounded.