Raycast to Mouse Inaccurate

Unity Engine
1

I can’t understand why this isn’t working, I’m casting a ray to my mouse with a fairly simple script, but it seems to be casting it a little off to the left or right. If I try to cast straight up, it will cast maybe 10 degrees to the right? I’m casting the ray from the player, here’s my script,

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

public class GrapplingHook : MonoBehaviour
{
    public bool grappling;

    LineRenderer ropeRenderer;

    [SerializeField] Transform anchor,grappleHook;

    Camera cam;

    [SerializeField] float maxGrappleDistance = 20;
    [SerializeField] LayerMask groundLayer;


    private void Start()
    {
        cam = Camera.main;
        ropeRenderer = GetComponent<LineRenderer>();
    }
    private void Update()
    {
        if (Input.GetMouseButtonDown(0))
        {
            LaunchGrapple();
        }
        if (Input.GetMouseButtonDown(1))
        {
            ReleaseGrapple();
        }

        if (grappling)
        {
            ropeRenderer.positionCount = 2;
            ropeRenderer.SetPosition(0, anchor.position);
            ropeRenderer.SetPosition(1, grappleHook.position);
        }
       
    }

    void LaunchGrapple()
    {

        RaycastHit2D hit = Physics2D.Raycast(anchor.position,cam.ScreenToWorldPoint(Input.mousePosition),maxGrappleDistance,groundLayer);

        if (hit.collider != null)
        {
            grappling = true;
            grappleHook.transform.position = hit.point;
           
        }
    }
    void ReleaseGrapple()
    {
        grappling = false;
        ropeRenderer.positionCount = 0;
        grappleHook.transform.position = transform.position;
    }


}

And here’s a video showing the issue,

So as you can see I’m drawing a line from the anchor position(which is a child of the player) to the grapple point(which is a child of the anchor) and moving the grapple point to the ray’s point. But why does it seem to be off? Unless I aim it at a perfect up-right or up-left angle…

Thanks.

2

The second parameter should be the direction vector of your array, not the target position of the array. You would want something like this:

RaycastHit2D hit = Physics2D.Raycast( anchor.position, cam.ScreenToWorldPoint(Input.mousePosition) - anchor.position, maxGrappleDistance, groundLayer);
2 Likes
3

Raycast takes an origin and direction. You’re passing it two points in space. You want to use Linecast, or change your second parameter.

1 Like
4

Using @GroZZleR 's solution could also work, however LineCast would not continue past the mouse’s position (if I understand it correctly), and would need a bit more complicated math to get it to do what you wanted.

5

Ohh, that’s right. 2D rays always throw me for a loop lol. It’s working now, thank you :slight_smile:

6

This is for non-2D raycast, but the same applies to 2D: Use named arguments ALWAYS.

Use Physics.Raycast() always with named arguments because it contains many poorly-designed overloads:

https://discussions.unity.com/t/758115/8

By naming the arguments you would instantly spot the error.

1 Like