UniVRM/Assets/VRM10_Samples/ClothSample/SphereTriangle/TriangleCapsuleGizmo.cs

using UnityEngine;


namespace SphereTriangle
{
    public class TriangleCapsuleGizmo : MonoBehaviour
    {
        public Transform B;
        public Transform C;
        public SphereCapsuleCollider Capsule;

        void Reset()
        {
            for (int i = 0; i < transform.childCount; ++i)
            {
                switch (i)
                {
                    case 0:
                        if (this.B == null) B = transform.GetChild(i);
                        break;

                    case 1:
                        if (this.C == null) C = transform.GetChild(i);
                        break;
                }
            }
        }

        [SerializeField]
        TriangleCapsuleCollisionSolver _solver = new();

        public void OnDrawGizmos()
        {
            if (B == null) return;
            if (C == null) return;
            var t = new Triangle(transform.position, B.position, C.position);

            if (Capsule?.Tail == null) return;
            var capsule = new LineSegment(Capsule.transform.position, Capsule.Tail.position);

            _solver.BeginFrame();
            var result = _solver.Collide(t, Capsule, capsule, Capsule.Radius);
            var type = result.TryGetClosest(out var l);
            if (!type.HasValue)
            {
                Gizmos.color = Color.gray;
                t.DrawGizmos();
                return;
            }

            _solver.DrawGizmos(t, 1.0f, Capsule.Radius);

            Gizmos.color = Color.magenta;
            Gizmos.DrawLine(l.Start, l.End);
            Gizmos.DrawSphere(l.End, 0.01f);
            Gizmos.DrawWireSphere(l.Start, 0.02f);

            var delta = l.Vector.normalized * (Capsule.Radius - l.Length);
            Gizmos.color = Color.green;
            Gizmos.DrawLine(l.End, l.End + delta);
            Gizmos.DrawSphere(l.End + delta, 0.01f);
        }
    }
}