[Solved] Instantiate Object on Raycast2D hit and rotate Instance

Unity Engine
1

I want to move an instance of a gameObject along the outline of another gameobject. Its a 2D Project in Unity.
My current Code:

Vector3 mousePosition = m_camera.ScreenToWorldPoint(Input.mousePosition);
    RaycastHit2D hit = Physics2D.Raycast(new Vector2(mousePosition.x, mousePosition.y), new Vector2(player.transform.position.x, player.transform.position.y));
    if (hit.collider != null &&  hit.collider.gameObject.tag == "Player") {
        if (!pointerInstance) {
            pointerInstance = Instantiate(ghostPointer, new Vector3(hit.point.x, hit.point.y, -1.1f), Quaternion.identity);
        } else if(pointerInstance) {
            pointerInstance.gameObject.transform.position = new Vector3(hit.point.x, hit.point.y, -1.1f);
            pointerInstance.gameObject.transform.eulerAngles = new Vector3(0f, 0f, hit.normal.x);
        }

    }

Unfortunately, the gameObject doesn’t rotate towards the mouse and the position on the left side of the playerObject is also sometimes off. I tried to use Instantiate() with Quaternion.LookRotation(hit.normal), but no luck either.

Here a rough sketch of what I want to achieve:

Any help is appreciated. Thanks!

2

Have you tried looking at the documentation for Physics2D.Raycast ? That shows you that the second argument is a direction, not a world position which I presume is your problem.

If you want to perform a cast between two points (line segment) then use Physics2D.Linecast.

If your player is just a circle of a specific radius then you do not need to use physics queries, just some simple math. From your diagram, calculate a normalized direction from the player position (2D) to the mouse position (2D) and scale that by the player radius. Here’s some pseudo code:

Vector2 mousePos = <blah>;
Vector2 playerPos = <blah>;
float playerRadius = <blah>;
var hitPoint = playerPos + ((mousePos - playerPos).normalized * playerRadius);
3

Thank you! In the meantime, I found a workaround but this information is definitely helpful for future projects.

I also learned that it’s better to use Mathematical way instead of a physical way(Raycasting) because in raycasting you have to throw ray several time for checking hit point, it could make your game lag.

4

Raycasting is fast, more so if you use the non-allocating ones. You’re doing something wrong if they’re taking too much time.

Less code is always faster so yeah, if there’s a simple algorithm then use it.