Preset Collisions

In DOTS Dynamic Bone the Preset Collision System simpily refers to colliders generated with/within the DOTSDynamicBoneCollider Component. The reason for this system is to allow the developer to either define a specific set of Entities to collide with or to collide with simple some simple shape data. When you add the DOTSDynamicBoneCollider Component it adds a DynamicBuffer<DOTSDynamicBoneCollider_BufferElement> which holds the data retaining to your Preset Colliders. This data is used everyframe to perform come collision calculations.

Here's an example oh how to add a DOTS Dynamic Bone Entity to the Preset collision system:

public class DOTSDynamicBoneAddToPresetCollisionSystemExample : SystemBase
{
    protected override void OnUpdate()
    {
        // Get Collider Entity
        ...
        Entity colliderEntity;
        Unity.Physics.PhysicsCollider otherEntityCollider = GetComponentData<Unity.Physics.PhysicsCollider>(colliderEntity);

        ...


        Entities.
            WithName("AddBoneToPresetCollisionSystemJob")
            .WithoutBurst()
            .WithAll<DOTSDynamicBone_AddToPresetCollisionSystem_Tag>()
            .WithNone<DOTSDynamicBone.Collision.DOTSDynamicBoneNaturalCollider_Tag>()
            .WithReadOnly(colliderEntity)
            .WithReadOnly(otherEntityCollider)
            .ForEach((Entity e,ref DOTSDynamicBone.DOTSDynamicBone boneData,ref DynamicBuffer<DOTSDynamicBone.Particle> particles)=> {
                // set the UseNaturalColliders property to true to use the Particle's PhysicsCollider
                boneData.UseNaturalColliders = true;
                // add the buffer. NOTE: this should invalidate the DynamicBuffer<DOTSDynamicBone.Particle> buffer so we have to get it again
                DynamicBuffer<DOTSDynamicBoneCollider_BufferElement> m_Colliders = AddBuffer<DOTSDynamicBoneCollider_BufferElement>(e);
                particles = GetBuffer<DOTSDynamicBone.Particle>(e);

                //now let's add a preset collider
                m_Colliders.add(new DOTSDynamicBoneCollider_BufferElement
                    {
                        m_Direction = TransformsExtensions.Direction.Y,
                        enabled = true,
                        fallbackToParicleRadiusOnNullPhysicsCollider = true,
                        entity = colliderEntity,
                        m_Radius = 0.5f,
                        boneEntity = e,
                        transform = new ParticleTransform(), //<- you may want to set this yourself
                        useUnityPhysicsCollider = true,
                        useParticlePhysicsCollider = true,
                        m_Bound = TransformsExtensions.Bound.Outside,
                        m_Center = new float3(),
                        persistant = true,
                        colliderPtr = otherEntityCollider
                    });

                // let's add the Unity.Physics.PhysicsCollider to each respective particle.
                // let's also disable collision calculations for every Particle who ith index is divisiable by 2 just because we can. 
                for(int i = 0; i < particles.Length; i++)
                {
                    DOTSDynamicBone.Particle p = particles[i];

                    p.m_ExcludeFromCollision = i % 2 == 0;  // exclude from collision if i mod 2 == 0

                    // if the m_TransformEntity has a PhysicsCollider then set it
                    unsafe
                    {
                        if (HasComponent<Unity.Physics.PhysicsCollider>(p.m_TransformEntity))
                        {
                            Unity.Physics.PhysicsCollider col = GetComponent<Unity.Physics.PhysicsCollider>(p.m_TransformEntity);

                            if (col.IsValid && col.Value.IsCreated)
                                p.collider = col.ColliderPtr;
                            else p.collider = null;
                        }
                        else p.collider = null;
                    }

                    particles[i] = p;
                }

                // these two functions are not Burstable. this addition and removal should be done
                // elsewhere. This is just an example.
                EntityManager.AddComponentData(e, new DOTSDynamicBone.Collision.DOTSDynamicBoneNaturalCollider_Tag { });
                EntityManager.RemoveComponent<DOTSDynamicBone_AddToCollisionSystem_Tag>(e);

            })
            .Run();

    }
}
public struct DOTSDynamicBone_AddToPresetCollisionSystem_Tag : IComponentData { }
public struct DOTSDynamicBone_RemoveFromPresetCollisionSystem_Tag : IComponentData { }

[]

This Component has the data nessacary to perform wither a Natural Collision or a