This script gives you objects screen size in pixels

Here is a script that gives you an objects bounding size in pixels. So, you can use it to calculate lod or anything else like that.

usage: pixelSize variable is what you need, make a circle texture and put it in, and move your object around to see the size of it.

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class AngleT : MonoBehaviour {
5.    
6.     public Transform target;
7.     public Texture2D texture;
8.    
9.     private float distance;
10.     private float diameter;
11.     private float angularSize;
12.     private float pixelSize;
13.     private Vector3 scrPos;
14.    
15.     void Start () {
16.         diameter = target.collider.bounds.extents.magnitude;
17.     }
18.    
19.     void Update () {
20.         distance = Vector3.Distance(target.position, Camera.main.transform.position);
21.         angularSize = (diameter / distance) * Mathf.Rad2Deg;
22.         pixelSize = ((angularSize * Screen.height) / Camera.main.fieldOfView);
23.         scrPos = Camera.main.WorldToScreenPoint (target.position);
24.     }
25.    
26.     void OnGUI () {
27.         GUI.DrawTexture (new Rect(scrPos.x-pixelSize/2, Screen.height-scrPos.y-pixelSize/2, pixelSize, pixelSize), texture);
28.     }
29. }

 

nice, thanks for sharing this, i have seen many people asking for something like this before

 

A slight addition, and it should be a bit faster because it only uses one division:

Code (CSharp):

1.  
2. //Get the screen size of an object in pixels, given its distance and diameter.
3. float DistanceAndDiameterToPixelSize(float distance, float diameter){
4.        
5.     float pixelSize = (diameter * Mathf.Rad2Deg * Screen.height) / (distance * Camera.main.fieldOfView);
6.     return pixelSize;
7. }
8.  
9. //Get the distance of an object, given its screen size in pixels and diameter.
10. float PixelSizeAndDiameterToDistance(float pixelSize, float diameter){
11.  
12.     float distance = (diameter * Mathf.Rad2Deg * Screen.height) / (pixelSize * Camera.main.fieldOfView);
13.     return distance;
14. }
15.  
16. //Get the diameter of an object, given its screen size in pixels and distance.
17. float PixelSizeAndDistanceToDiameter(float pixelSize, float distance){
18.  
19.     float diameter = (pixelSize * distance * Camera.main.fieldOfView) / (Mathf.Rad2Deg * Screen.height);
20.     return diameter;
21. }
22.