CatmullRomSpline曲线

CatmullRomSpline.cs

using System.Collections.Generic;
using UnityEngine;

public static class CatmullRomSpline
{
    public static void DrawCatmullRomSpline(LineRenderer lineRenderer, params Vector3[] targets)
    {
        if (targets == null || targets.Length <= 0) return;
        var pos = new List<Vector3>();

        var current = 0;
        // 绘制 0 ~ n-1
        for (; current < targets.Length - 1; current++)
        {
            // 第一个点相关的四个点为 0,0,1,2
            if (current == 0)
            {
                GetCatmullRomSplinePos(pos, targets[0], targets[0], targets[1], targets[2]);
            }
            // 倒数第二个点  n-3, n-2, n-1, n-1
            else if (current == targets.Length - 2)
            {
                GetCatmullRomSplinePos(pos, targets[current - 1], targets[current], targets[current + 1], targets[current + 1]);
            }
            else
            {
                GetCatmullRomSplinePos(pos, targets[current - 1], targets[current], targets[current + 1], targets[current + 2]);
            }
        }

        lineRenderer.positionCount = pos.Count;
        lineRenderer.SetPositions(pos.ToArray());
    }

    private static void GetCatmullRomSplinePos(List<Vector3> pos, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
    {
        var resulotion = 0.01f;
        var loops = Mathf.FloorToInt(1f / resulotion);
        for (var i = 0; i <= loops; i++)
        {
            pos.Add(GetCatmullRomPosition(i * resulotion, p0, p1, p2, p3));
        }
    }

    private static Vector3 GetCatmullRomPosition(float t, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
    {
        var a = 2 * p1;
        var b = p2 - p0;
        var c = 2 * p0 - 5 * p1 + 4 * p2 - p3;
        var d = -p0 + 3 * p1 - 3 * p2 + p3;

        return 0.5f * (a + (b * t) + (c * t * t) + (d * t * t * t));
    }
}

推荐阅读：

• 知乎专栏：https://zhuanlan.zhihu.com/p/141977882
• 猫教程，贝塞尔相关：https://catlikecoding.com/unity/tutorials/curves-and-splines/
• Unity插件：https://assetstore.unity.com/packages/tools/utilities/curvy-splines-8-212532
• Unity商店也有不少Spline相关的插件