Help : Need To Draw a Box

Questions & Answers
1

I need to know how to draw a box that starts at Input.GetMouseButtonDown(0) and continues to render and change size until Input.GetMouseButtonUp(0). And based on the mouse position. I cant figure out where to start.

2

Here’s an example to get you started:

using UnityEngine;

public class MouseBox : MonoBehaviour {

	bool _isValid;	// 
	bool _isDown;
	Vector2 _mouseDownPos;
	Vector2 _mouseLastPos;
	
	// Update is called once per frame
	void Update () {
		// Detect when mouse button is down
		if (Input.GetMouseButtonDown(0)) {
			_mouseDownPos = Input.mousePosition;
			_isDown = true;
			_isValid = true;
		}

		// Continue tracking mouse position until the button is raised
		if (_isDown) {
			_mouseLastPos = Input.mousePosition;
			if (Input.GetMouseButtonUp(0)) {
				_isDown = false;
				// If you want the box to vanish now, just set 'isValid' to false.
			}
		}
	}

	void OnGUI() {
		if (_isValid) {
			// Find the corner of the box
			Vector2 origin;
			origin.x = Mathf.Min(_mouseDownPos.x, _mouseLastPos.x);
			// GUI and mouse coordinates are the opposite way around.
			origin.y = Mathf.Max(_mouseDownPos.y, _mouseLastPos.y);
			origin.y = Screen.height - origin.y;	
			//Compute size of box
			Vector2 size = _mouseDownPos - _mouseLastPos;
			size.x = Mathf.Abs(size.x);
			size.y = Mathf.Abs(size.y);		
			// Draw it!
			Rect r = new Rect(origin.x, origin.y, size.x, size.y);
			GUI.Box(r, "");
		}
	}
}