Calculate orthographic size

Hi,

I'm trying to calculate the correct orthographic size.

My camera is rotate : 30,45,0
I have created a quad with the size of 20
The orthographic size should be around 10.6 to fill the screen with the quad.

But how can i calculate this value??

 

I made a component which may help you:

Code (CSharp):

1. using UnityEngine;
2.  
3. [ExecuteInEditMode]
4. public class CameraSizeFit : MonoBehaviour
5. {
6.     public Vector2 minSize = new Vector2(10, 5);
7.     public bool fitToObject;
8.     public bool lookAt;
9.     public GameObject fitObject;
10.  
11.     private Camera cam;
12.     private new Transform transform;
13.  
14.     void Awake ()
15.     {
16.         cam = GetComponent<Camera>();
17.         transform = GetComponent<Transform>();
18.     }
19.  
20.     void Update ()
21.     {
22.         if (lookAt && fitObject)
23.             transform.LookAt(fitObject.transform.position);
24.  
25.         var minSize = EvaluateSize();
26.         cam.orthographicSize = CalculateOrtographicSize(minSize);
27.     }
28.  
29.  
30.     private Vector2 EvaluateSize()
31.     {
32.         Vector2 size = minSize;
33.  
34.         if (fitToObject && fitObject) {
35.             Bounds bounds;
36.             if (FetchObjectBounds(fitObject, out bounds)) {
37.                 CalculateSizeFromBounds(bounds, ref size);
38.             }
39.         }
40.  
41.         return size;
42.     }
43.  
44.  
45.     private float CalculateOrtographicSize(Vector2 size)
46.     {
47.         float aspect = Screen.width / (float)Screen.height; // not using cam.aspect because it is not always updated immediately
48.         float height = size.x / aspect;
49.         if (height < size.y) height = size.y;
50.         return height / 2;
51.     }
52.  
53.  
54.     // returns false if object bounds could not be determined
55.     private bool FetchObjectBounds(GameObject obj, out Bounds bounds)
56.     {
57.         var renderer = obj.GetComponent<Renderer>();
58.         if (renderer) {
59.             bounds = renderer.bounds;
60.             return true;
61.         }
62.  
63.         var collider = obj.GetComponent<Collider>();
64.         if (collider) {
65.             bounds = collider.bounds;
66.             return true;
67.         }
68.  
69.         bounds = new Bounds();
70.         return false;
71.     }
72.  
73.  
74.     // returns false if calculated size was not valid
75.     private bool CalculateSizeFromBounds(Bounds bounds, ref Vector2 size)
76.     {
77.         bounds = TransformBounds(bounds);
78.         if (bounds.size.x > float.Epsilon && bounds.size.y > float.Epsilon) {
79.             size = bounds.size;
80.             return true;
81.         }
82.         return false;
83.     }
84.  
85.  
86.     private static Vector3[] extentPoints = new Vector3[8]; // array reused by TransformBounds method, don't do this in a multithreaded application
87.  
88.     private Bounds TransformBounds(Bounds bounds)
89.     {
90.         Vector3 cen = bounds.center;
91.         Vector3 ext = bounds.extents;
92.         extentPoints[0] = transform.InverseTransformPoint(new Vector3(cen.x - ext.x, cen.y - ext.y, cen.z - ext.z));
93.         extentPoints[1] = transform.InverseTransformPoint(new Vector3(cen.x + ext.x, cen.y - ext.y, cen.z - ext.z));
94.         extentPoints[2] = transform.InverseTransformPoint(new Vector3(cen.x - ext.x, cen.y - ext.y, cen.z + ext.z));
95.         extentPoints[3] = transform.InverseTransformPoint(new Vector3(cen.x + ext.x, cen.y - ext.y, cen.z + ext.z));
96.         extentPoints[4] = transform.InverseTransformPoint(new Vector3(cen.x - ext.x, cen.y + ext.y, cen.z - ext.z));
97.         extentPoints[5] = transform.InverseTransformPoint(new Vector3(cen.x + ext.x, cen.y + ext.y, cen.z - ext.z));
98.         extentPoints[6] = transform.InverseTransformPoint(new Vector3(cen.x - ext.x, cen.y + ext.y, cen.z + ext.z));
99.         extentPoints[7] = transform.InverseTransformPoint(new Vector3(cen.x + ext.x, cen.y + ext.y, cen.z + ext.z));
100.  
101.         Vector3 min = extentPoints[0];
102.         Vector3 max = extentPoints[0];
103.         foreach (Vector3 v in extentPoints) {
104.             min = Vector3.Min(min, v);
105.             max = Vector3.Max(max, v);
106.         }
107.  
108.         bounds.SetMinMax(min, max);
109.         return bounds;
110.     }
111.  
112. }
113.  

 

Great script! Helps me make my old school point and click adventure game with non moving backgrounds.