How to make a capsule collider detect which direction it collided with something?

I’m trying to implement ground detection through collision. I have a gameobject with a RigidBody and a Capsule Collider components. Objects tagged as "Ground" that collide with this gameobject would make it so that the gameobject is grounded (this means it can jump).

However, I realize it would be better if it also can distinguish where it collided. If an object with the tag "Ground" collided on the upper or middle part of the gameobject but not on the bottom where its feet would be, then the object collision should not register to the gameobject that it is grounded.

How do I account for that?

Here is my code so far:

// paste code here
  1. Add Multiple Colliders:
  • Keep the existing Capsule Collider for the overall collision detection.
  • Add additional colliders for specific areas, such as upper, middle, and lower parts of the gameobject.
  1. Raycasting:
  • Use raycasts to check for collisions at specific points or directions.
  • For example, you can cast rays downward from the upper, middle, and lower parts of the gameobject to check if they hit an object with the “Ground” tag.
  1. Handle Collisions:
  • When a collision is detected, check the hit point of the raycast.
  • If the collision occurs at the lower part (feet), consider it as grounding.
  • If the collision occurs at the upper or middle part, you may choose not to register it as grounding.

Here’s a simplified example in Unity:

GroundDetection.cs

public class GroundDetection : MonoBehaviour
{
    public LayerMask groundLayer;

    void Update()
    {
        // Perform raycasts from different points
        if (IsGrounded(transform.position)) 
        {
            // The object is grounded, allow jumping
        }
    }

    bool IsGrounded(Vector3 position)
    {
        float rayLength = 0.1f; // Adjust as needed
        Vector3 upperPoint = position + Vector3.up * 1.0f; // Example: upper part
        Vector3 middlePoint = position; // Example: middle part
        Vector3 lowerPoint = position - Vector3.up * 1.0f; // Example: lower part

        // Check for collisions using raycasts
        bool upperHit = Physics.Raycast(upperPoint, Vector3.down, rayLength, groundLayer);
        bool middleHit = Physics.Raycast(middlePoint, Vector3.down, rayLength, groundLayer);
        bool lowerHit = Physics.Raycast(lowerPoint, Vector3.down, rayLength, groundLayer);

        // Customize this logic based on your requirements
        return lowerHit;
    }
}

The collision object you get in your OnCollisionEnter contains a normal vector. Or rather, multiple normal vectors, because a collision can have multiple ContactPoints. Those vectors tell you a direction of the force applied by the collision.