Resolved How do I change the collision filter of an entity through code?

Here's what I tried (doesn't work):

Code (CSharp):

1. Unity.Entities.Entity myEntity = [...]
2. Unity.Entities.EntityManager myManager = [...]
3. Unity.Physics.CollisionFilter newFilter = [...]
4.  
5. Unity.Physics.PhysicsCollider pc = myManager.GetComponentData<Unity.Physics.PhysicsCollider>(myEntity);
6. pc.Value.Value.Filter = newFilter;
7. myManager.SetComponentData(myEntity, pc);

In

pc.Value.Value.Filter

the first "Value" is a field and the second "Value" is a get-only property BUT it returns a ref, which is why I thought I should be able to set it. Guess not.

How do I change the filter? Does it involve pc.ColliderPtr and unsafe code?

 

Hello!

I found the scene that makes custom filter, that is located in Physics samples, domo>Quiery > CustomCollector.scene

But they did some magic here, Only game objects with named "Glass Wall" are converted to entity with custom filter which is "transparent"

.
But I don't know how they made this!

You can find the code from there. BUt they are not located near the scene directory.

https://drive.google.com/file/d/1izC1-DEO4wRLKh_DWD8eBSs4Gbm_T_OR/view?usp=sharing

 

https://drive.google.com/file/d/18IVGgk3T6XuCdZRBb8w_3TFnA_v7k4DD/view?usp=sharing


Apologies, this custom "transparent" tag was in physics shape inspector. And was created in the editor manually.

 

Have tried doing this but it didn't work:

Code (CSharp):

1. Unity.Entities.Entity myEntity = [...]
2. Unity.Entities.EntityManager myManager = [...]
3.  
4. UnityEngine.Debug.Log(1u << (9));  //512 (original)
5. UnityEngine.Debug.Log(1u << (5));  //32 (desired)
6.  
7. Unity.Physics.PhysicsCollider pc = myManager.GetComponentData<Unity.Physics.PhysicsCollider>(myEntity);
8. UnityEngine.Debug.Log(pc.Value.Value.Filter.BelongsTo);  //512 (original filter)
9. unsafe {
10.     Unity.Physics.Collider* c1 = pc.ColliderPtr;
11.     Unity.Physics.CollisionFilter cf1 = c1->Filter;
12.     cf1.BelongsTo = 1u << (5);
13.     cf1.CollidesWith = 1u << (5);
14.     c1->Filter = cf1;
15.     Unity.Physics.Collider* c2 = (Unity.Physics.Collider*) pc.Value.GetUnsafePtr();
16.     Unity.Physics.CollisionFilter cf2 = c2->Filter;
17.     cf2.BelongsTo = 1u << (5);
18.     cf2.CollidesWith = 1u << (5);
19.     c2->Filter = cf2;
20. }
21. UnityEngine.Debug.Log(pc.Value.Value.Filter.BelongsTo);  //512 (still original filter)
22. myManager.SetComponentData(myEntity, pc);

Do I have to create a new Unity.Physics.PhysicsCollider and can't modify the existing one?

Edit:

pc.ColliderPtr

and

pc.Value.GetUnsafePtr()

points to the same thing. If I cast the pointer to Unity.Physics.MeshCollider instead of just Unity.Physics.Collider then

c1->Filter

becomes a get-only property instead of a get-set property. I really don't want to have to make a new MeshCollider just to update the filter, someone help me out here. Calling Unity.Physics.MeshCollider.Create() is expensive.

 

Tried going through the leaves of the MeshCollider and changing their CollisionFilters (

polyCol->Filter

below is a get-set property). Didn't work.

Code (CSharp):

1. //{ (inside the change collision filter method)
2.     Unity.Physics.PhysicsCollider pc = myManager.GetComponentData<Unity.Physics.PhysicsCollider>(myEntity);
3.     unsafe {
4.         Unity.Physics.Collider* c1 = pc.ColliderPtr;
5.         if (c1->Type==Unity.Physics.ColliderType.Mesh) {
6.             Unity.Physics.MeshCollider* mc = (Unity.Physics.MeshCollider*)pc.ColliderPtr;
7.             LeafCollector collector = new LeafCollector();
8.             mc->GetLeaves<LeafCollector>(ref collector);
9.         } else {
10.             //unimplemented
11.         }
12.     }
13.     myManager.SetComponentData(myEntity, pc);
14. //}
15.  
16. private struct LeafCollector : Unity.Physics.ILeafColliderCollector {
17.     public void AddLeaf(Unity.Physics.ColliderKey key, ref Unity.Physics.ChildCollider leaf) {
18.         unsafe {
19.             Unity.Physics.CollisionFilter cf = new Unity.Physics.CollisionFilter();
20.             cf.BelongsTo = 1u << (5);
21.             cf.CollidesWith = 1u << (5);
22.             Unity.Physics.PolygonCollider* polyCol = (Unity.Physics.PolygonCollider*)leaf.Collider;
23.             polyCol->Filter = cf;
24.         }
25.     }
26.     public void PopCompositeCollider(uint numCompositeKeyBits, Unity.Physics.Math.MTransform worldFromParent) {}
27.     public void PushCompositeCollider(Unity.Physics.ColliderKeyPath compositeKey, Unity.Physics.Math.MTransform parentFromComposite, out Unity.Physics.Math.MTransform worldFromParent) {worldFromParent = parentFromComposite;}
28. }

Halp!

 

Ah, this seems like an issue.

Setting the filter directly on the mesh collider makes no sense, because it's just a combination of child filters. However, when you change individual filters of leaf colliders (triangles), mesh needs to rebuild that combined filter, and I suppose it doesn't.

Unfortunately, I think you'll need to change the code a bit to make this work. After changing the filters of all leaf colliders, you need to "inform" the mesh of new filter. In the Create() method there is a block of code:

// Calculate combined filter
meshCollider->m_Header.Filter = mesh.Sections.Length > 0 ? mesh.Sections[0].Filters[0] : CollisionFilter.Default;
for (int i = 0; i < mesh.Sections.Length; ++i)
{
for (var j = 0; j < mesh.Sections.Filters.Length; ++j)
{
var f = mesh.Sections.Filters[j];
meshCollider->m_Header.Filter = CollisionFilter.CreateUnion(meshCollider->m_Header.Filter, f);
}
}

Try putting it in a method and calling that method after you change the filters. Something like "UpdateMeshFilter()" or similar.

I'll investigate a proper fix. Let me know if this works for you.

 

@petarmHavok: I don't think I will venture into modifying Unity's code, if I edit Unity.Physics.MeshCollider.Create() now chances are I will need to do it again in the next version of DOTS, or it will no longer be needed in which case I've just wasted time that could have been spent on the actual game. So I'll wait for that proper fix.

If not setFilter() or setMaterial() can be implemented then maybe a quicker version of Unity.Physics.MeshCollider.Create() that takes an already-created MeshCollider as 1st parameter and copies everything from it except the filter and material (parameter 2 and 3)?

Edit: Changing the thread's prefix from "Help Wanted" to "Resolved" but it's not really resolved.
I'm just waiting for that fix.

 

Working on that fix at the moment. Hopefully I can get it in for next release (mid-December is current guess).

 

Out of curiosity, what is your use case with changing the filter of the mesh collider?

 

Nice!

The game can have units that exist in the same spot but can't interact because they are on different "planes of existence" however they can pass into each others "planes" through certain spots and should then start colliding with stuff on that "plane". Kind of like if they are ghosts to each other until they move onto the same "plane".

 

Just an update that the fix went in and will be available mid-January. Let me know if it works for you.