RaycastHit2D.normal

説明

レイにより衝突された表面の法線ベクトル

The normal vector of a surface is the vector that points outward perpendicularly at a given point on that surface. This vector can be useful in raycasting as a way to determine reflections or ricochets from projectiles or to align a character so that it stands upright on the surface.

using UnityEngine;

public class Example : MonoBehaviour
{
    public GameObject sprite;

    void Update()
    {
        if (Input.GetMouseButton(0))
        {
            Vector2 worldPoint = Camera.main.ScreenToWorldPoint(Input.mousePosition);
            RaycastHit2D hit = Physics2D.Raycast(worldPoint, sprite.transform.position);

            if (hit.collider != null)
            {
                // Draws a line from the normal of the object that you clicked
                Debug.DrawLine(sprite.transform.position, hit.normal, Color.yellow, 10.0f);
            }
        }
    }
}

Note: If a hit occurs starting inside a collider the collision normal is the opposite direction of the line/ray query.