Update BoxColliderFitChildren.cs

fix rotated objects, fix negative scale

Author: unitycoder

Assets/Scripts/Editor/ContextMenu/BoxColliderFitChildren.cs

@@ -1,6 +1,5 @@
 // Adjust Box Collider to fit child meshes inside
 // Usage: You have empty parent transform, with child meshes inside, add box collider to parent then use this
-// NOTE: Doesnt work if root transform is rotated
 
 using UnityEngine;
 using UnityEditor;
@@ -10,44 +9,52 @@ namespace UnityLibrary
     public class BoxColliderFitChildren : MonoBehaviour
     {
         [MenuItem("CONTEXT/BoxCollider/Fit to Children")]
-        static void FixSize(MenuCommand command)
+        static void FitColliderToChildren(MenuCommand command)
         {
             BoxCollider col = (BoxCollider)command.context;
 
-            // Record undo for undo functionality
+            // record undo
             Undo.RecordObject(col.transform, "Fit Box Collider To Children");
 
-            // Get transformed bounds relative to the collider object
-            Bounds localBounds = GetLocalBounds(col.transform);
+            // first reset transform rotation
+            var origRot = col.transform.rotation;
+            col.transform.rotation = Quaternion.identity;
 
-            // Set collider local center and size
-            col.center = localBounds.center;
-            col.size = localBounds.size;
-        }
+            // get child mesh bounds
+            var b = GetRecursiveMeshBounds(col.gameObject);
 
-        public static Bounds GetLocalBounds(Transform parent)
-        {
-            var renderers = parent.GetComponentsInChildren<Renderer>();
-            if (renderers.Length == 0)
-                return new Bounds(Vector3.zero, Vector3.zero); // No renderers
+            // set collider local center and size
+            col.center = col.transform.root.InverseTransformVector(b.center) - col.transform.position;
 
-            // Initialize bounds in local space
-            Bounds bounds = new Bounds(parent.InverseTransformPoint(renderers[0].bounds.center), 
-                                       parent.InverseTransformVector(renderers[0].bounds.size));
+            // keep size positive
+            var size = b.size;
+            size.x = Mathf.Abs(size.x);
+            size.y = Mathf.Abs(size.y);
+            size.z = Mathf.Abs(size.z);
 
-            // Encapsulate all child renderers
-            for (int i = 1; i < renderers.Length; i++)
-            {
-                var worldBounds = renderers[i].bounds;
+            col.size = b.size;
 
-                // Convert world bounds to local space
-                Vector3 localCenter = parent.InverseTransformPoint(worldBounds.center);
-                Vector3 localSize = parent.InverseTransformVector(worldBounds.size);
+            // restore rotation
+            col.transform.rotation = origRot;
+        }
 
-                bounds.Encapsulate(new Bounds(localCenter, localSize));
+        public static Bounds GetRecursiveMeshBounds(GameObject go)
+        {
+            var r = go.GetComponentsInChildren<Renderer>();
+            if (r.Length > 0)
+            {
+                var b = r[0].bounds;
+                for (int i = 1; i < r.Length; i++)
+                {
+                    b.Encapsulate(r[i].bounds);
+                }
+                return b;
+            }
+            else // TODO no renderers?
+            {
+                //return new Bounds(Vector3.one, Vector3.one);
+                return new Bounds();
             }
-
-            return bounds;
         }
     }
 }