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Question Raycast registers one hit per collider

Discussion in 'Physics for ECS' started by Drayanlia, Jul 13, 2023.

  1. Drayanlia


    Jan 14, 2021
    Hi there,

    I have a very simple scene with just a box entity with a physics shape and a physics body set to kinematic.
    I am trying to cast a ray through it and get the number of resulting hits. I expect to get two hits, one from "entering" the collider and one from "exiting" but only get one.

    I am under the impression it should be working since this is a very basic setup. Am I missing something ?

    Any help is much appreciated

    Code (CSharp):
    1.             var CollisionWorld = SystemAPI.GetSingleton<PhysicsWorldSingleton>().CollisionWorld;
    3.             var worldPosition = new int3(100, 200, 100);
    4.             var rayDirection = new int3(0, -1, 0);
    6.             var rayEnd = worldPosition + 1000 * rayDirection;
    8.             RaycastInput input = new RaycastInput()
    9.             {
    10.                 Start = worldPosition,
    11.                 End = rayEnd,
    12.                 Filter = new CollisionFilter
    13.                 {
    14.                     BelongsTo = 1u << 0,
    15.                     CollidesWith = 1u << 1,
    16.                     GroupIndex = 0,
    17.                 },
    18.             };
    20.             var hits = new NativeList<Unity.Physics.RaycastHit>(Allocator.Temp);
    22.             CollisionWorld.CastRay(input, ref hits);
    24.             var hitCount = hits.Length;
    25.             Debug.Log($"{hitCount}");
  2. Drayanlia


    Jan 14, 2021
    Seems like it actually is the intended behaviour. My bad.

    A straightforward solution is to cast a new ray from every new intersection point until no intersection is found but this sounds quite inefficient for my use case (checking if a point is inside a group of meshes). Will explore other solutions.