Question Drawing a rectangle around an object on screen

Hi all,

I am trying to achieve an effect where a window will pop up on screen next to an object with it's information when the mouse is hovering over a gameobject.

The gameobject has a collider with IsTrigger = true. So onMouseXXX works.

It is easy to get the position of the object on screen but I am struggling to calculate the size of the object in screen co-ordinates and especially when the camera moves.

My code so far is:

Code (CSharp):

1. using UnityEngine;
2.  
3.  
4. public class SelectionScript : MonoBehaviour
5. {
6.     private bool IsMouseOver;
7.     private Rect WindowRect = new(0, 0, 100, 100);
8.     private int WindowID;
9.     private string WindowName;
10.     Renderer _renderer;
11.  
12.     private void Start()
13.     {
14.         WindowID = GetHashCode();
15.         WindowName = gameObject.name;
16.         _renderer = GetComponent<Renderer>();
17.     }
18.  
19.     private void OnGUI()
20.     {
21.         if (!IsMouseOver) return;
22.  
23.         Rect rect = new Rect();
24.         rect.position = WorldToGuiPoint(gameObject.transform.position);
25.         // Ok, fine so far but how do I find the size o fthe object in screen space co-ordinates?
26.         // I know I can use renderer.bounds. min and max but this doesn't seem to take perspective into consideration..
27.         rect.width = 100;
28.         rect.height = 100;
29.         Utils.DrawScreenRectBorder(rect, 2, new Color(0.0f, 0.0f, 0.0f)); // This is a seperate script but works.
30.         // I would like the onGUI window to pop up on the top Right of the object and not obscure it (if it does
31.         // this can lead to a flickering effect if the cursor is over the object but also in the window as the
32.         // onMouseOver toggles on/off eavery other frame)
33.         WindowRect = GUILayout.Window(WindowID, WindowRect, WindowFunc, WindowName);
34.     }
35.  
36.     void WindowFunc(int id)
37.     {
38.         GUILayout.Label("Hello World");
39.     }
40.  
41.     private void OnMouseOver()
42.     {
43.         IsMouseOver = true;
44.     }
45.  
46.     private void OnMouseExit()
47.     {
48.         IsMouseOver = false;
49.     }
50.  
51.     public Vector2 WorldToGuiPoint(Vector3 GOposition)
52.     {
53.         Vector2 guiPosition = Camera.main.WorldToScreenPoint(GOposition);
54.         guiPosition.y = Screen.height - guiPosition.y;
55.         return guiPosition;
56.     }
57.  
58.     // Not used but for investigation purposes!
59.     public void OnDrawGizmos()
60.     {
61.         Renderer r = GetComponent<Renderer>();
62.         if (r == null)
63.             return;
64.         Gizmos.matrix = Matrix4x4.identity;
65.         Gizmos.color = Color.blue;
66.         Gizmos.DrawWireCube(r.bounds.center, r.bounds.extents * 2);
67.     }
68.  
69. }

Has anyone solved this problem or have any good ideas? Thank you in advance.

Michael

 

[Solved] (In a way I like anyway...!) Others may find it useful.

Code (CSharp):

1.  
2. using UnityEngine;
3.  
4. public class SelectionScript : MonoBehaviour
5. {
6.  
7.     public bool IsSelected;
8.     private bool IsMouseOver;
9.  
10.     private Rect WindowRect;
11.     private int WindowID;
12.     private string WindowName;
13.     Renderer _renderer;
14.     Color rectColour = Color.green;
15.     Vector2[] points;
16.  
17.     private void Start()
18.     {
19.         WindowID = GetHashCode();
20.         WindowName = gameObject.name;
21.         _renderer = GetComponent<Renderer>();
22.         points = new Vector2[8];
23.     }
24.  
25.     private void OnGUI()
26.     {
27.         if (!IsSelected) if (!IsMouseOver) return;
28.  
29.         Rect rect = Rect.zero;
30.         rect.position = WorldToGuiPoint(_renderer.bounds.center);
31.  
32.         float x = _renderer.bounds.extents.x;
33.         float y = _renderer.bounds.extents.y;
34.         float z = _renderer.bounds.extents.z;
35.  
36.         points[0] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(x, y, z));
37.         points[1] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(x, -y, z));
38.         points[2] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(x, y, -z));
39.         points[3] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(x, -y, -z));
40.         points[4] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(-x, y, z));
41.         points[5] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(-x, -y, z));
42.         points[6] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(-x, y, -z));
43.         points[7] = WorldToGuiPoint(_renderer.bounds.center + new Vector3(-x, -y, -z));
44.  
45.         foreach (Vector2 point in points)
46.         {
47.             rect = GrowRectangleToInlcudePoint(rect, point);
48.         }
49.  
50.         Utils.DrawScreenRectBorder(rect, 2, rectColour);
51.  
52.         WindowRect.position = new Vector2(rect.xMax, rect.yMin - WindowRect.height);
53.         WindowRect = GUILayout.Window(WindowID, WindowRect, WindowFunc, WindowName, GUILayout.MinWidth(80));
54.     }
55.  
56.     void WindowFunc(int id)
57.     {
58.         GUILayout.Label("Hello World", GUILayout.MinWidth(100));
59.     }
60.  
61.     private void OnMouseEnter()
62.     {
63.         IsMouseOver = true;
64.     }
65.  
66.     private void OnMouseExit()
67.     {
68.         IsMouseOver = false;
69.     }
70.  
71.     private void OnMouseDown()
72.     {
73.         IsSelected = !IsSelected;
74.         if (IsSelected)
75.         {
76.             rectColour = Color.red;
77.         }
78.         else
79.         {
80.             rectColour = Color.green;
81.         }
82.     }
83.  
84.     public Vector2 WorldToGuiPoint(Vector3 pos)
85.     {
86.         Vector2 guiPosition = Camera.main.WorldToScreenPoint(pos);
87.         guiPosition.y = Screen.height - guiPosition.y;
88.         return guiPosition;
89.     }
90.  
91.  
92.     Rect GrowRectangleToInlcudePoint(Rect rect, Vector2 p)
93.     {
94.         if (!rect.Contains(p))
95.         {
96.             if (p.x < rect.xMin)
97.                 rect.xMin = p.x;
98.             else if (p.x > rect.xMax)
99.                 rect.xMax = p.x;
100.  
101.             if (p.y < rect.yMin)
102.                 rect.yMin = p.y;
103.             else if (p.y > rect.yMax)
104.                 rect.yMax = p.y;
105.         }
106.         return rect;
107.     }
108.  
109.     // Not used but for investigation purposes!
110.     //public void OnDrawGizmos()
111.     //{
112.     //    Renderer r = GetComponent<Renderer>();
113.     //    if (r == null)
114.     //        return;
115.     //    Gizmos.matrix = Matrix4x4.identity;
116.     //    Gizmos.color = Color.blue;
117.     //    Gizmos.DrawWireCube(r.bounds.center, r.bounds.extents * 2);
118.     //    Gizmos.DrawSphere(r.bounds.center, 0.1f);
119.     //    float x = r.bounds.extents.x;
120.     //    float y = r.bounds.extents.y;
121.     //    float z = r.bounds.extents.z;
122.     //    Gizmos.color = Color.yellow;
123.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(x, y, z), 0.1f);
124.     //    Gizmos.color = Color.blue;
125.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(x, -y, z), 0.1f);
126.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(x, y, -z), 0.1f);
127.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(x, -y, -z), 0.1f);
128.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(-x, y, z), 0.1f);
129.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(-x, -y, z), 0.1f);
130.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(-x, y, -z), 0.1f);
131.     //    Gizmos.DrawSphere(r.bounds.center + new Vector3(-x, -y, -z), 0.1f);
132.     //}
133.  
134. }

 

Oh, and Utils is...(which I've lifted form somewhere but I can't remember who coded it originally - sorry)

Code (CSharp):

1. using UnityEngine;
2.  
3. public static class Utils
4. {
5.     public static Rect GetScreenRect(Vector3 screenPosition1, Vector3 screenPosition2)
6.     {
7.         // Move origin from bottom left to top left
8.         screenPosition1.y = Screen.height - screenPosition1.y;
9.         screenPosition2.y = Screen.height - screenPosition2.y;
10.         // Calculate corners
11.         var topLeft = Vector3.Min(screenPosition1, screenPosition2);
12.         var bottomRight = Vector3.Max(screenPosition1, screenPosition2);
13.         // Create Rect
14.         return Rect.MinMaxRect(topLeft.x, topLeft.y, bottomRight.x, bottomRight.y);
15.     }
16.  
17.     public static Bounds GetViewportBounds(Camera camera, Vector3 screenPosition1, Vector3 screenPosition2)
18.     {
19.         var v1 = Camera.main.ScreenToViewportPoint(screenPosition1);
20.         var v2 = Camera.main.ScreenToViewportPoint(screenPosition2);
21.         var min = Vector3.Min(v1, v2);
22.         var max = Vector3.Max(v1, v2);
23.  
24.         min.z = camera.nearClipPlane;
25.         max.z = camera.farClipPlane;
26.  
27.         var bounds = new Bounds();
28.  
29.         bounds.SetMinMax(min, max);
30.  
31.         return bounds;
32.     }
33.  
34.     public static void DrawScreenRect(Rect rect, Color color)
35.     {
36.         GUI.color = color;
37.         GUI.DrawTexture(rect, Texture2D.whiteTexture);
38.         GUI.color = Color.white;
39.     }
40.  
41.     public static void DrawScreenRectBorder(Rect rect, int thickness, Color color)
42.     {
43.         Utils.DrawScreenRect(new Rect(rect.xMin, rect.yMin, rect.width, thickness), color);
44.         Utils.DrawScreenRect(new Rect(rect.xMin, rect.yMin, thickness, rect.height), color);
45.         Utils.DrawScreenRect(new Rect(rect.xMax - thickness, rect.yMin, thickness, rect.height), color);
46.         Utils.DrawScreenRect(new Rect(rect.xMin, rect.yMax - thickness, rect.width, thickness), color);
47.     }
48. }