Spline.cs

using System.Collections.Generic;
using UnityEngine;
 
namespace ARLocation
{
    public enum SplineType
    {
        CatmullromSpline,
        LinearSpline,
    }
 
    public abstract class Spline
    {
 
        public Vector3[] Points { get; protected set; }
 
        protected Curve[] segments;
 
        protected int segmentCount = 0;
 
        public float Length { get; protected set; }
 
        protected float[] lengths;
 
        public abstract void CalculateSegments(int n);
 
        public Vector3 GetPointAtArcLength(float s)
        {
            s = Mathf.Clamp(s, 0, Length);
 
            for (var i = 0; i < segmentCount; i++)
            {
                if (s <= lengths[i])
                {
                    var offset = i == 0 ? 0 : lengths[i - 1];
                    return segments[i].GetPointAtLength(s - offset);
                }
            }
            return segments[segmentCount - 1].GetPoint(1);
        }
 
        public CurvePointData GetPointAndTangentAtArcLength(float s)
        {
            s = Mathf.Clamp(s, 0, Length);
 
            for (var i = 0; i < segmentCount; i++)
            {
                if (s <= lengths[i])
                {
                    var offset = i == 0 ? 0 : lengths[i - 1];
                    return segments[i].GetPointAndTangentAtLength(s - offset);
                }
            }
            return segments[segmentCount - 1].GetPointAndTangentAtLength(1);
        }
 
        public void DrawCurveWithLineRenderer(LineRenderer renderer, System.Func<Vector3, Vector3> func, int n = 100)
        {
            var points = new List<Vector3>();
 
            float s = 0.0f;
            while (s <= Length)
            {
                var pointData = GetPointAndTangentAtArcLength(s);
                points.Add(func(pointData.point));
                s += Length / (n + 1.0f);
            }
 
            var arr = points.ToArray();
            renderer.positionCount = arr.Length;
            renderer.SetPositions(arr);
        }
 
        public Vector3[] SamplePoints(int n, System.Func<Vector3, Vector3> func)
        {
            var sample = new Vector3[n + 2];
            var delta = Length / (n + 1.0f);
 
            var s = 0.0f;
            for (var i = 0; i < (n + 2); i++)
            {
                sample[i] = func(GetPointAtArcLength(s));
                s += delta;
            }
 
            return sample;
        }
 
        public Vector3[] SamplePoints(int n)
        {
            return SamplePoints(n, (p) => p);
        }
 
        public void DrawGizmos()
        {
            DrawPointsGizmos();
            DrawCurveLengthGizmos();
        }
 
        private void DrawPointsGizmos()
        {
            foreach (var p in Points)
            {
                Gizmos.color = Color.blue;
                Gizmos.DrawSphere(p, 0.1f);
            }
        }
 
        private void DrawCurveLengthGizmos()
        {
            var p = GetPointAtArcLength(0f);
            float s = 0.0f;
            while (s <= Length)
            {
                Gizmos.color = Color.green;
                var pointData = GetPointAndTangentAtArcLength(s);
                Vector3 n = pointData.point;
                Gizmos.DrawLine(p, n);
                p = n;
                s += 0.1f;
                Gizmos.color = Color.magenta;
                var tan = pointData.tangent;
                Gizmos.color = Color.blue;
                Gizmos.DrawLine(n, n + tan);
            }
        }
    }
}