Using collision attributes in complex scenes

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My personal understanding is this. When there are many types of objects in the scene, collisions need to be detected between each pair, which may consume a lot of performance.
This area of the document is relatively thin. I checked a lot of information and got a rough idea of how to use it, but I personally think it needs to be verified.

In this case we can use collisionMask and collisionGroup together.
collisionGroup：default is -1, collisions can only occur if they are in the same group :yum:
collisionMask: default is -1, it can set which group to collide with
1）If the value of MeshA’s collisionMask is the same as the value of MeshB’s collisionGroup, it can definitely collide. But that’s not what I want to explain
2）The values of MeshA’s collisionGroup and MeshB’s collisionGroup are equal, but MeshA.collisionMask !== MeshB.collisionGroup, can this situation collide? The answer I got so far is false, The priority of collisionMask is greater than collisionGroup :thinking:
3）collisionMask can specify multiple collisionGroups through the mask’s characteristics. Convert to binary bitwise AND，If the same digits are all 1, they can collide， as follows:

  • Group A: 0b0001 (1)
  • Group B: 0b0010 (2)
  • Group C: 0b0100 (4)
  • Group D: 0b1000 (8)
    box.collisionMask = 0b0110 (6), can Can collide with Group B and Group C
    If collisionMask is ob1111 then it can collide with a b c d
    :stuck_out_tongue_winking_eye:

If there is no problem with my understanding, I hope my post can help some people

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I want to modify the second point. The equal here is incorrect. Refer to the third point. The bitwise AND of the same bits is equal to 1.

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