simple raycasting issue

Unity Engine
1

Setup:
I have the project setup in 2D (the camera’s projection is orthographic). The scene contains only 1 camera and a sprite.
The sprite has a Circle Collider 2D component and its bounding circle encompasses the entire sprite.
The camera contains the following script :

	void Update()
	{
		GameObject.Find("MousePositionText").guiText.text = 
Input.mousePosition.x.ToString() + ", " + Input.mousePosition.y.ToString();

		if( Input.GetMouseButtonDown(0) )
		{
			RaycastHit hit;
			Ray ray = Camera.main.ScreenPointToRay( Input.mousePosition );
			
			if( Physics.Raycast(ray, out hit) )
				GameObject.Find("TargetHitText").guiText.text = "We clicked on the sprite!";
			else
				GameObject.Find("TargetHitText").guiText.text = "We missed the sprite!";
		}
	}

The camera is positioned at (0,0,-10) with its near plane = 0.3 and far = 1000.
The sprite is positioned at (-4,2,0)

I keep on getting “We missed the sprite!” every single time I click on the sprite. Can someone help me out? Thanks!

2

Try the Physics2D.Raycast.

              RaycastHit2D hit;
              Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
              
              if(Physics2D.Raycast(ray, out hit))
3

I don’t think the Physics2D.Raycast is the correct API I should be using for this purpose. From the documentation (Unity - Scripting API: Physics2D.Raycast) it seems like it’s only for casting a ray along the xy-plane, where as I want to cast a ray from from a point on screen into the 3D world.

Anyway, I changed the camera’s projection to Perspective and it still doesn’t work… so maybe it’s not an issue with whether it’s orthographic or not but something else I’m doing wrong?

4

There isn’t any support for that yet but Unity has said it will be added. You could use a tiny circle collider trigger instead and just check if it fires a message.

5

Sooo… I just found out something interesting… if I create a cube in the scene and I click on it, this

if( Physics.Raycast(ray, out hit) )
                GameObject.Find("TargetHitText").guiText.text = "We clicked on the sprite!";

is true and the appropriate text appears.

Why does it work with 3D objects but not sprites?

6

Because it’s part of Physx only, not Box2D.

7

Do you mean that there isn’t any support for raycast detection against sprites?

[edit]
Oh I see…