Raycast from 2D canvas object to world space

Questions & Answers
1

After playing around with the code long enough, I answered my own question. I’ll post it here for all or any who have the same problem I had:

Using a Main Camera, with a child Canvas, with a child ‘Square UI Object’(cursor). How to make Main Camera use a Raycast that aims at the ‘cursor’. And find and get the ‘Selected’ object returned and use for other scripts…

Using C# in Unity 5.6…

public class MainCameraControl : MonoBehaviour {

    public GameObject cursor;
	public float cursorSpeed;
	public GameObject Selected;

	float posX;
	float posY;

	void Start() {}

	void Update () {
		KeyboardMove ();

		if (Input.GetKeyUp (KeyCode.RightShift))  //The "{ }" doesn't need to be called because there's only one solution
			CheckRay ();                          //Since it's update, you don't want the ray called every frame

		if (Input.GetKeyUp (KeyCode.RightControl)) {
			if (Selected != null) {
				//Destroy (Selected);
				Debug.Log ("Last selected: " + Selected.name);
			}		
		}

	}

	private void CheckRay() {
		
		posX = cursor.transform.localPosition.x + 375f;   //These offsets may be needed, or changed for different purposes
		posY = cursor.transform.localPosition.y + 150f;   //Check your scene while game is running, and make sure DrawRay is active

		Ray ray = Camera.main.ScreenPointToRay(new Vector3(posX, posY, 0));
			//Debug.DrawRay(ray.origin, ray.direction * 10, Color.yellow);      //DrawRay - delete back slashes to activate
		RaycastHit hit;
		if (Physics.Raycast(ray, out hit, 100))
			Debug.Log("You have selected the " + hit.collider.name);
		Selected = hit.collider.gameObject;
	}

	private void KeyboardMove(){         //I created these functions down here, to clean the Update space

		if (Input.GetKey (KeyCode.UpArrow))
			cursor.transform.Translate(Vector2.up * cursorSpeed * Time.deltaTime);
		if (Input.GetKey (KeyCode.DownArrow))
			cursor.transform.Translate(Vector2.down * cursorSpeed * Time.deltaTime);
		if (Input.GetKey (KeyCode.LeftArrow))
			cursor.transform.Translate(Vector2.left * cursorSpeed * Time.deltaTime);
		if (Input.GetKey (KeyCode.RightArrow))
			cursor.transform.Translate(Vector2.right * cursorSpeed * Time.deltaTime);
	}
}
2

I finally figured it out! The cursor position on the canvas is not only different from worldspace, but it is also a different position when you call ScreenPointToRay (which counts pixels out from the bottom left corner of the canvas, being 0,0).

Here is the proper code for Unity 5.6 in C#:

public GameObject cursor; //drag n drop UI object in inspector
public Canvas canvas; //drag n drop canvas in inspector
float pixelX;
float pixelY;
float posX;
float posY;

void Start () 
{
	pixelX = canvas.worldCamera.pixelWidth;
	pixelY = canvas.worldCamera.pixelHeight;
}

void Update(){
	
	CheckRay();
}

void CheckRay(){
	
	posX = cursor.transform.localPosition.x + pixelX / 2f;   
	posY = cursor.transform.localPosition.y + pixelY / 2f;   
	Vector3 cursorPos = new Vector3 (posX, posY, 0);
	//OR- Ray ray = Camera.main.ScreenPointToRay(new Vector3(posX, posY, 0));
	Ray ray = Camera.main.ScreenPointToRay(cursorPos);
		Debug.DrawRay(ray.origin, ray.direction * 10, Color.yellow);

}