Building Placement Bug

Unity Engine
1

Hi everyone,

I’m encountering the following problem.
I have a button that instantiates a prefab to the current mouse position and can rotate with the mouse scroll wheel. But when I press the button to instantiate it, the prefab does something weird.
I have recorded a video about this problem and I hope there is someone here that can explain me why that I have this problem and how to solve it?

The link to the video:
https://drive.google.com/open?id=1elWyqspLpzizAx6eDlALUNtKww0UuyPi

The code that I use for placing objects:

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

public class BuildPrefab : MonoBehaviour
{
    //GAMEOBJECTS
    public GameObject placeableObjectPrefab;
    public GameObject currentPlaceableObject;

    //FLOATS
    private float mouseWheelRotation;
    public float RotationAmount = 45f;

    //BOOLEANS
    public bool isClicked = false;

    public void Select()
    {
        isClicked = true;
    }

    private void Update()
    {
        InstantiatePrefab();

        if (currentPlaceableObject != null)
        {
            MoveCurrentObjectToMouse();
            RotateFromMouseWheel();
            ReleaseIfClicked();
        }
    }

    private void InstantiatePrefab()
    {
        if (isClicked)
        {
            if (Input.GetMouseButtonDown(1))
            {
                currentPlaceableObject = null;
                isClicked = false;
            }
            else if (!Input.GetMouseButtonDown(1))
            {
                currentPlaceableObject = Instantiate(placeableObjectPrefab);
            }
        }
    }

    private void MoveCurrentObjectToMouse()
    {
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);

        RaycastHit hit;
        if (Physics.Raycast(ray, out hit))
        {
            currentPlaceableObject.transform.position = hit.point;
            currentPlaceableObject.transform.rotation = Quaternion.FromToRotation(Vector3.up, hit.normal);
        }
    }

    private void RotateFromMouseWheel()
    {
        Debug.Log(Input.mouseScrollDelta);
        mouseWheelRotation += Input.mouseScrollDelta.y;
        currentPlaceableObject.transform.Rotate(Vector3.up, mouseWheelRotation * RotationAmount);
    }

    private void ReleaseIfClicked()
    {
        if (Input.GetMouseButtonDown(0))
            currentPlaceableObject = null;

        isClicked = false;
    }
}
2

Your issue is that the raycast is hitting the object you just tried to place.

3

So how do I fix this? I’m still learning.

4

I did not download and watch the videos (it is probably better to upload them on a well-known portal), but assuming @lordconstant got it on point, then you have to ignore the object you want to place.

When there’s no more logic involved, you can choose either of those:

  1. Remove/disable the colliders of the object you want to place (or the preview object) and ensure you add/enable them afterwards.
  2. Assign a specific layer and make sure that layer is ignored by your raycast (there are overloads of the raycasting functions that take layer masks). There is already a pre-defined layer for that: the IgnoreRaycast layer. When you use that one, you won’t need to change the raycast at all, because that layer is already ignored by that API.
5

Thanks for answering, after somewhile I have finally found the solution to this!
I’ve wrote this line of code “currentPlaceableObject.layer = 11;” in the wrong place.
The wright place is that works for me:

private void ReleaseIfClicked()
    {
        if (Input.GetMouseButtonDown(0))
        {
            currentPlaceableObject.layer = 11;
            currentPlaceableObject = null;
        }

        isClicked = false;
    }