1- // Adjust Box Collider to fit child meshes inside
2- // Usage: You have empty parent transform, with child meshes inside, add box collider to parent then use this
3- 41using UnityEngine ;
52using UnityEditor ;
63
@@ -13,48 +10,62 @@ static void FitColliderToChildren(MenuCommand command)
1310 {
1411 BoxCollider col = ( BoxCollider ) command . context ;
1512
16- // record undo
13+ // Record undo
1714 Undo . RecordObject ( col . transform , "Fit Box Collider To Children" ) ;
1815
19- // first reset transform rotation
20- var origRot = col . transform . rotation ;
21- col . transform . rotation = Quaternion . identity ;
16+ // Get world-space bounds of all child meshes
17+ var worldBounds = GetRecursiveMeshBounds ( col . gameObject ) ;
2218
23- // get child mesh bounds
24- var b = GetRecursiveMeshBounds ( col . gameObject ) ;
19+ if ( worldBounds . size == Vector3 . zero )
20+ {
21+ Debug . LogWarning ( "No valid meshes found to fit the BoxCollider." ) ;
22+ return ;
23+ }
2524
26- // set collider local center and size
27- col . center = col . transform . root . InverseTransformVector ( b . center ) - col . transform . position ;
25+ // Convert world-space center to local space
26+ Vector3 localCenter = col . transform . InverseTransformPoint ( worldBounds . center ) ;
2827
29- // keep size positive
30- var size = b . size ;
31- size . x = Mathf . Abs ( size . x ) ;
32- size . y = Mathf . Abs ( size . y ) ;
33- size . z = Mathf . Abs ( size . z ) ;
28+ // Convert world-space size to local space
29+ Vector3 localSize = col . transform . InverseTransformVector ( worldBounds . size ) ;
3430
35- col . size = b . size ;
31+ // Ensure size is positive
32+ localSize = new Vector3 ( Mathf . Abs ( localSize . x ) , Mathf . Abs ( localSize . y ) , Mathf . Abs ( localSize . z ) ) ;
33+ 34+ // Fix potential center flipping
35+ if ( Vector3 . Dot ( col . transform . right , Vector3 . right ) < 0 )
36+ {
37+ localCenter . x = - localCenter . x ;
38+ }
39+ if ( Vector3 . Dot ( col . transform . up , Vector3 . up ) < 0 )
40+ {
41+ localCenter . y = - localCenter . y ;
42+ }
43+ if ( Vector3 . Dot ( col . transform . forward , Vector3 . forward ) < 0 )
44+ {
45+ localCenter . z = - localCenter . z ;
46+ }
3647
37- // restore rotation
38- col . transform . rotation = origRot ;
48+ // Apply to collider
49+ col . center = localCenter ;
50+ col . size = localSize ;
3951 }
4052
4153 public static Bounds GetRecursiveMeshBounds ( GameObject go )
4254 {
43- var r = go . GetComponentsInChildren < Renderer > ( ) ;
44- if ( r . Length > 0 )
45- {
46- var b = r [ 0 ] . bounds ;
47- for ( int i = 1 ; i < r . Length ; i ++ )
48- {
49- b . Encapsulate ( r [ i ] . bounds ) ;
50- }
51- return b ;
52- }
53- else // TODO no renderers?
54- {
55- //return new Bounds(Vector3.one, Vector3.one);
55+ Renderer [ ] renderers = go . GetComponentsInChildren < Renderer > ( ) ;
56+ 57+ if ( renderers . Length == 0 )
5658 return new Bounds ( ) ;
59+ 60+ // Start with the first renderer’s bounds in world space
61+ Bounds worldBounds = renderers [ 0 ] . bounds ;
62+ 63+ for ( int i = 1 ; i < renderers . Length ; i ++ )
64+ {
65+ worldBounds . Encapsulate ( renderers [ i ] . bounds ) ;
5766 }
67+ 68+ return worldBounds ;
5869 }
5970 }
6071}
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