Standard Selecting Rectangle

Hey,

Sorry for this pretty easy question. Im new to Unity.

Can someone tell me how to draw a rectangle on the screen.
Like in any strategy game or on Windows Desktop etc.

Press somewhere with left mouse button.
Keep button pressed.
Move mouse around and see a rectangle from starting point to the actual mouse position.

Therefor I need to know 2 things:
1. Input.mousePosition is a bit weird, because it is a 3D-Vector. But the screen ist just 2D obviously.
So can I simply use Input.mousePosition.x and Input.mousePosition.y ?

2. What is the best way to draw the rectangle ?
Shall I use GUI.Box or anything else ?

Greetings,
Shera

 

Hi there!
1) Yes, Input.mousePosition is Vector3, but z-property of it always 0, so you can use x and y properties for screen coordinates.
2) I thing that using of GUI.Box with custom style is the easiest and most convinient way to draw rectangle on sceen.

 

This is an old post, but when I was looking for a solution to get a selection rectangle drawing in game mode, also in a build version, then there were not really satisfying answers. Most tried via some assets packages or either Line Renderer or Shaders, which I found to be overloaded for what I was trying to achieve.

I finally managed to build it myself with very few code and want to share for everyone else googling in the future, enjoy:

Code (CSharp):

1.  
2. using UnityEngine;
3. /// <summary>
4. /// Draws a selection rectangle on the left mouse button down & dragging
5. ///
6. /// You only need an InputReceiverManager that basically tracks
7. /// - if the left mouse button is currently down and saves it in "LeftMouseButtonDown"
8. /// - saves the initial click position when mouse button was clicked  and saves it in "InitialMousePositionOnLeftClick"
9. /// - updates the current mouse position and saves it in "CurrentMousePosition"
10. ///
11. /// </summary>
12. public class SelectionRectangleDrawer : MonoBehaviour
13. {
14.     //set color via inspector for the selection rectangles filler color
15.     public Color SelectionRectangleFillerColor;
16.     //set color via inspector for the selection rectangles border color
17.     public Color SelectionRectangleBorderColor;
18.     //set selection rectangles  border thickness
19.     public int SelectionRectangleBorderThickness = 2;
20.     private Texture2D _selectionRectangleFiller;
21.     private Texture2D _selectionRectangleBorder;
22.     private bool _drawSelectionRectangle;
23.     private float _x1, _x2, _y1, _y2;
24.     private Vector2 pos1, pos2;
25.     void Start()
26.     {
27.         _selectionRectangleFiller = new Texture2D(1, 1);
28.         _selectionRectangleFiller.SetPixel(0, 0, SelectionRectangleFillerColor);
29.         _selectionRectangleFiller.Apply();
30.         _selectionRectangleFiller.wrapMode = TextureWrapMode.Clamp;
31.         _selectionRectangleFiller.filterMode = FilterMode.Point;
32.         _selectionRectangleBorder = new Texture2D(1, 1);
33.         _selectionRectangleBorder.SetPixel(0, 0, SelectionRectangleBorderColor);
34.         _selectionRectangleBorder.Apply();
35.         _selectionRectangleBorder.wrapMode = TextureWrapMode.Clamp;
36.         _selectionRectangleBorder.filterMode = FilterMode.Point;
37.     }
38.     void Update()
39.     {
40.         if (InputReceiverManager.Instance.LeftMouseButtonDown && !Mathf.Approximately(Vector2.Distance(InputReceiverManager.Instance.CurrentMousePosition,
41.                                                                                                        InputReceiverManager.Instance.InitialMousePositionOnLeftClick), 0f))
42.             _drawSelectionRectangle = true;
43.         else if (!InputReceiverManager.Instance.LeftMouseButtonDown && _drawSelectionRectangle)
44.             _drawSelectionRectangle = false;
45.     }
46.     private void OnGUI()
47.     {
48.         if (_drawSelectionRectangle)
49.             drawSelectionRectangle();
50.     }
51.     private void drawSelectionRectangle()
52.     {
53.         pos1 = InputReceiverManager.Instance.InitialMousePositionOnLeftClick;
54.         pos2 = InputReceiverManager.Instance.CurrentMousePosition;
55.         //check initial mouse position on X axis versus dragging mouse position
56.         if (pos1.x < pos2.x)
57.         {
58.             _x1 = pos1.x;
59.             _x2 = pos2.x;
60.         }
61.         else
62.         {
63.             _x1 = pos2.x;
64.             _x2 = pos1.x;
65.         }
66.         //check initial mouse position on Y axis versus dragging mouse position
67.         if (pos1.y < pos2.y)
68.         {
69.             _y1 = pos1.y;
70.             _y2 = pos2.y;
71.         }
72.         else
73.         {
74.             _y1 = pos2.y;
75.             _y2 = pos1.y;
76.         }
77.         //filler
78.         GUI.DrawTexture(new Rect(_x1, Screen.height - _y1, _x2 - _x1, _y1 - _y2), _selectionRectangleFiller, ScaleMode.StretchToFill);
79.         //top line
80.         GUI.DrawTexture(new Rect(_x1, Screen.height - _y1, _x2 - _x1, -SelectionRectangleBorderThickness), _selectionRectangleBorder, ScaleMode.StretchToFill);
81.         //bottom line
82.         GUI.DrawTexture(new Rect(_x1, Screen.height - _y2, _x2 - _x1, SelectionRectangleBorderThickness), _selectionRectangleBorder, ScaleMode.StretchToFill);
83.         //left line
84.         GUI.DrawTexture(new Rect(_x1, Screen.height - _y1, SelectionRectangleBorderThickness, _y1 - _y2), _selectionRectangleBorder, ScaleMode.StretchToFill);
85.         //right line
86.         GUI.DrawTexture(new Rect(_x2, Screen.height - _y1, -SelectionRectangleBorderThickness, _y1 - _y2), _selectionRectangleBorder, ScaleMode.StretchToFill);
87.     }
88. }
89.  
90.  
91.