Create custom physic material

1) How can I create a physic material with custom properties?
For example, Unity's physic material has a few properties and I need one more just for holding a value inside.

I tried to create CustomPhysicMaterial script but I have a problem with asset creation of this script.



When Unity creates its physic material it takes a <.physicMaterial> type.
2) How can I create a <.physicMaterial> files from CustomPhysicMaterial script?

 

I am after this as well. I got to a point in my game where I would like to add some per physic material properties like footstep sounds and particles etc.

I am obviously using a scriptable object approach as of now, but I dont like it. It forces me to use a "Collidable" component on gameObjects that have a Collider just so I can reference this scriptable object. I could totally get rid of this component if I could inject my own data/fields in the PhysicMaterial asset instead...

It doesnt seem that complicated to implement, apparently PhysicMaterial is just a YAML file like ScriptableObject's. I came up with this code setup, but it doens't work, the Editor doesn't serialize the field.

Code (CSharp):

1.     public class CustomPhysicMaterial : PhysicMaterial
2.     {
3.         public AudioClip footstepSound;
4.  
5. #if UNITY_EDITOR
6.         [UnityEditor.MenuItem("Assets/Create/hickV/CustomPhysicMaterial")]
7.         public static void CreateAsset()
8.         {
9.             CustomPhysicMaterial cPM = new CustomPhysicMaterial();
10.  
11.             string path = UnityEditor.AssetDatabase.GetAssetPath(UnityEditor.Selection.activeObject);
12.  
13.             if (path == "")
14.             {
15.                 path = "Assets";
16.             }
17.             else if (Path.GetExtension(path) != "")
18.             {
19.                 path = path.Replace(Path.GetFileName(UnityEditor.AssetDatabase.GetAssetPath(UnityEditor.Selection.activeObject)), "");
20.             }
21.             UnityEditor.AssetDatabase.CreateAsset(cPM, UnityEditor.AssetDatabase.GenerateUniqueAssetPath(path + "/CustomPhysicMaterial.physicMaterial"));
22.         }
23. #endif
24.     }