Mouse Position Woes

Unity Engine
1

I’ve done some serious googling related to placing objects on screen where the mouse is located. Currently I’m using this function, which is called in Update()

blah is a GameObject
point1 is a Vector3

void ScreenClick()
	{
		if(Input.GetKeyDown(KeyCode.Mouse0))
		{
				point1 = mainCam.ScreenToWorldPoint(Input.mousePosition);
				point1.z = 0;
				Debug.Log (point1);
				Debug.Log (Input.mousePosition);
				Instantiate(blah, point1, transform.rotation);
		}
	}

When I left click, it spawns object’s at the camera’s location [0,1,-10], regardless of where I click…(I set the z to 0 in the next line so the object always spawns in front of the camera @ [0,1,0].

What am I doing wrong? In the debug, point1 is always (0,1,0) and the mousePos is always correct/changing…but the ScreenToWorldPoint does not seem to be functioning.

2

setting z to 0 is not going to put it in front of the camera unless the camera z is below 0.

z should probably be mainCam.position.z + 10 (or maybe its minus… not sure off the top of my head)…

3

It is, the camera is -10…that’s not the problem though, I just wanted to clarify why I set it to 0. The problem is that the objects are always spawning at (0,1,0) when it should be (x,y,0) where x and y are the current mouse position in world space.

4

Firstly, you’re setting z to 0 in world space, not the local space of the camera.

Secondly, where are the colliders in your scene? ScreenToWorldPoint uses a raycast, so if there’s a hidden collider/trigger in front of your camera it may be hitting that, and if there’s not a collider on the thing you expect to hit it’ll be ignored.

Thirdly, how is your camera set up? I can’t remember what I was doing the other day, but I recall having similar results with an ortho camera… ah yes. I was moving something to the clicked position, but the thing I was moving was clickable itself, so every frame it moved closer to the camera by its radius (because every frame the mouse was down I was “clicking on it” and moving it to the point on its collider where I’d clicked).

5

I want a z of 0. The game is a side scroller, so all the objects have the same z value.

There are no colliders in the scene, save a cube and a sphere. Clicking on their locations does not alter where the objects is instantiated. After reading your post I created a plane with a mesh collider (disabled the mesh renderer) and put it in the scene. However, this did not fix the issue, it still spawns @ (0,1,0) everytime.

I’m using the default perspective camera.

Thanks for all the responses! Much appreciated!

EDIT: It makes sense now as to why I need a collider in the scene. The mouse to world position could change depending on where the collider is. I have a plane with mesh collider now encompassing the whole scene, and it does not seem to have changed anything. Do I need to use a simple collider?

6

maybe try using ViewportToWorldPoint

7

Solved

Thanks again everyone for the pointers. You helped me out a bunch. I solved this by setting the z to the camera plane.

Example code:

mousePos = Input.mousePosition;
mousePos.z = (Camera.main.farClipPlane-2);
point = Camera.main.ScreenToWorldPoint(mousePos);
Instantiate(blah, point, transform.rotation);

You can also use the nearClipPlane if you’d like. Anyway, once I used this, everything functioned correctly. Thanks again, I hope this helps someone in the future who has a similar problem.