ScreenToWorldPoint gives inaccurate values

Unity Engine
1

Hi guys,

I am having a problem in ScreenToWorldPoint conversion and I cannot figure out the problem. Here is the problem.

I have a cube in the scene in the position of -21.59, 1.28, -95.24 Rotation -90.00 in the Y axis. I want to get the cube position in the word space when I click on the object. The idea is I want to get the position of the cube when the screen coordinates are given.

This is the script

public class CoordinatesConverter : MonoBehaviour {

    public GameObject CCTVcamera;
    private Camera currCamera;
    void Start () {
        currCamera = CCTVcamera.GetComponent<Camera> () as Camera;
    }
 
    // Update is called once per frame
    void Update () {
        if (Input.GetMouseButtonDown (0)) {
            Vector3 mousePosFar = new Vector3 (Input.mousePosition.x, Input.mousePosition.y, currCamera.farClipPlane);
            Vector3 mousePosNear = new Vector3 (Input.mousePosition.x, Input.mousePosition.y, currCamera.nearClipPlane);

            Vector3 mousePosF = currCamera.ScreenToWorldPoint (mousePosFar);
            Vector3 mousePosN = currCamera.ScreenToWorldPoint (mousePosNear);

            Debug.DrawRay (mousePosN,mousePosF-mousePosN,Color.green);

            print ("mouse xy " + Input.mousePosition.x + " #### " + Input.mousePosition.y);
            print ("world xyz " + mousePosN.x + " $$ " + mousePosN.y + " $$ " + mousePosN.z);
        }
    }

}

The problem is the word xyz values are not correct. y and z values are somewhat correct but the x value various when I move the camera. I think the problem is with z-depth value. I am using currCamera.nearClipPlane . What I found is when I go close to the cube and click on it, it gives almost correct position for the cube. When I go far away from the cube it gives wrong x value. Need some help to figure out the problem. :slight_smile:

Basically speaking I want to get the position of the object when I give the screen coordinates. Below is a picture of my scene.

2

You can’t get the world position of the cube using ScreenToWorldPoint as you need to know the Z value (the one you supply to the ScreenToWorldPoint function). To get the exact point you could use Camera.ScreenPointToRay which would tell you exactly where on the cube the pixel is (under the screen point).

3

Thank you for correcting me.I will try it out :slight_smile:

4

@tonemcbride Thanks a lot! It worked :slight_smile:

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