MagnetismHeroes/Assets/MagnetismHeroes/UnityRuntime/Presentation/ContactPlacement.cs

using System.Collections.Generic;
using UnityEngine;

namespace MagnetismHeroes.UnityRuntime.Presentation
{
    public static class ContactPlacement
    {
        // Leave the union of unit-sphere overlap intervals along the chosen contact direction.
        // Translating the whole friend preserves its shape, including two identical rows.
        public static float Clearance(IReadOnlyList<Vector3> moving, IReadOnlyList<Vector3> stationary, Vector3 direction)
        {
            var intervals = new List<(float start, float end)>();
            foreach (var source in moving)
                foreach (var target in stationary)
                {
                    var offset = source - target; float along = Vector3.Dot(offset, direction);
                    float perpendicularSquared = offset.sqrMagnitude - along * along;
                    if (perpendicularSquared >= 1) continue;
                    float half = Mathf.Sqrt(Mathf.Max(0, 1 - perpendicularSquared));
                    intervals.Add((-along - half, -along + half));
                }
            intervals.Sort((a, b) => a.start.CompareTo(b.start)); float distance = 0;
            foreach (var interval in intervals)
                if (interval.start < distance + .0001f && interval.end > distance) distance = interval.end;
            return distance;
        }
    }
}