【Unity3D BezierCurve绘制曲线】使用贝塞尔曲线公式与LineRenderer绘制曲线形成路径

近日，项目需求：前提：三维空间

1.动态添加（删除）路径点，通过两个以上的路径点来绘制曲线，删除点之后不影响其他点绘制曲线；

2.每个路径点都可以被拖拽发生位移，可以通过锁定某个轴，使该轴不发生位移；

3.每个路径点处有两个可调节点（首尾只有一个调节点），可通过调节点来调节曲线切线（速度方向线）斜率，以达到平滑曲线；

4.使该曲线形成路径，隐藏曲线，Player沿曲线完成自动寻路。

先看效果，再贴代码。（使用贝塞尔曲线公式与LineRenderer绘制3D可调节曲线）

代码如下：两个脚本。

1. DMDrawCurve.cs 挂载到任意对象即可

该脚本实现绘制曲线，动态添加（删除）点，发生位移时更新绘制曲线，以及隐藏该曲线。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace DM.Editor.View
{
    [RequireComponent(typeof(LineRenderer))]
    public class DMDrawCurve : MonoBehaviour
    {
        public List m_allPoints;
        private GameObject m_anchorPoint;
        private GameObject m_controlPoint;
        private GameObject m_pointParent;
        private LineRenderer m_lineRenderer;
        
        private int m_curveCount = 0;
        private int SEGMENT_COUNT = 60;//曲线取点个数（取点越多这个长度越趋向于精确）

        private static DMDrawCurve m_instance;
        public static DMDrawCurve Instance
        {
            get {
                if (null == m_instance)
                    m_instance = new DMDrawCurve();
                return m_instance;
            }
        }
        void Awake()
        {
            if (null == m_instance)
                m_instance = this;
            SetLine();
            if (null == m_anchorPoint)
                m_anchorPoint = Resources.Load("Prefabs/AnchorPoint") as GameObject;
            if (null == m_controlPoint)
                m_controlPoint = Resources.Load("Prefabs/ControlPoint") as GameObject;
        }
        void SetLine()
        {
            if (null == m_lineRenderer)
                m_lineRenderer = GetComponent();
            m_lineRenderer.material = Resources.Load("Materials/Line") as Material;
            m_lineRenderer.startColor = Color.red;
            m_lineRenderer.endColor = Color.green;
            m_lineRenderer.widthMultiplier = 0.2f;
        }

        public void Init(GameObject player)
        {//初始化一个基准点（Player）
            if (player == null) return;
            GameObject anchorPoint = LoadPoint(m_anchorPoint, player.transform.position);
            m_allPoints.Add(anchorPoint.transform);
        }      
        public void AddPoint(Vector3 anchorPointPos)
        {
            //初始化时m_allPoints添加了一个player
            if (m_allPoints.Count == 0) return;
            Transform lastPoint = m_allPoints[m_allPoints.Count - 1];
            GameObject controlPoint2 = LoadPoint(m_controlPoint, lastPoint.position+new Vector3(0,0,-1));   
            GameObject controlPoint = LoadPoint(m_controlPoint, anchorPointPos + new Vector3(0, 0, 1));
            GameObject anchorPoint = LoadPoint(m_anchorPoint, anchorPointPos);

            anchorPoint.GetComponent().m_controlObject = controlPoint;
            lastPoint.GetComponent().m_controlObject2 = controlPoint2;

            m_allPoints.Add(controlPoint2.transform);
            m_allPoints.Add(controlPoint.transform);
            m_allPoints.Add(anchorPoint.transform);

            DrawCurve();
        }
        public void DeletePoint(GameObject anchorPoint)
        {
            if (anchorPoint == null) return;
            CurvePointControl curvePoint = anchorPoint.GetComponent();
            if (curvePoint && anchorPoint.tag.Equals("AnchorPoint"))
            {
                if (curvePoint.m_controlObject)
                {
                    m_allPoints.Remove(curvePoint.m_controlObject.transform);
                    Destroy(curvePoint.m_controlObject);
                } 
                if (curvePoint.m_controlObject2)
                {
                    m_allPoints.Remove(curvePoint.m_controlObject2.transform);
                    Destroy(curvePoint.m_controlObject2);
                }
                if (m_allPoints.IndexOf(curvePoint.transform) == (m_allPoints.Count - 1))
                {//先判断删除的是最后一个元素再移除
                    m_allPoints.Remove(curvePoint.transform);
                    Transform lastPoint = m_allPoints[m_allPoints.Count - 2];
                    GameObject lastPointCtrObject = lastPoint.GetComponent().m_controlObject2;
                    if (lastPointCtrObject)
                    {
                        m_allPoints.Remove(lastPointCtrObject.transform);
                        Destroy(lastPointCtrObject);
                        lastPoint.GetComponent().m_controlObject2 = null;
                    }
                }
                else
                {
                    m_allPoints.Remove(curvePoint.transform);
                }
                Destroy(anchorPoint);
                if(m_allPoints.Count == 1)
                {
                    m_lineRenderer.positionCount = 0;
                }
            }

            DrawCurve();
        }
        public void UpdateLine(GameObject anchorPoint, Vector3 offsetPos1, Vector3 offsetPos2)
        {
            if (anchorPoint == null) return;
            if (anchorPoint.tag.Equals("AnchorPoint"))
            {
                CurvePointControl curvePoint = anchorPoint.GetComponent();
                if (curvePoint)
                {
                    if (curvePoint.m_controlObject)
                        curvePoint.m_controlObject.transform.position = anchorPoint.transform.position + offsetPos1;
                    if (curvePoint.m_controlObject2)
                        curvePoint.m_controlObject2.transform.position = anchorPoint.transform.position + offsetPos2;
                }
            }
            DrawCurve();
        }
        public List HiddenLine(bool isHidden=false)
        {
            m_pointParent.SetActive(isHidden);
            m_lineRenderer.enabled = isHidden;
            List pathPoints = new List();
            if(!isHidden)
            {
                for(int i = 0; i < m_lineRenderer.positionCount; i++)
                {
                    pathPoints.Add(m_lineRenderer.GetPosition(i));
                }
            }
            return pathPoints;
        }

        private void DrawCurve()//画曲线
        {
            if (m_allPoints.Count < 4) return;
            m_curveCount = (int)m_allPoints.Count / 3;
            for (int j = 0; j < m_curveCount; j++)
            {
                for (int i = 1; i <= SEGMENT_COUNT; i++)
                {
                    float t = (float)i / (float)SEGMENT_COUNT;
                    int nodeIndex = j * 3;
                    Vector3 pixel = CalculateCubicBezierPoint(t, m_allPoints[nodeIndex].position, m_allPoints[nodeIndex + 1].position, m_allPoints[nodeIndex + 2].position, m_allPoints[nodeIndex + 3].position);
                    m_lineRenderer.positionCount = j * SEGMENT_COUNT + i;
                    m_lineRenderer.SetPosition((j * SEGMENT_COUNT) + (i - 1), pixel);
                }
            }
        }
        private GameObject LoadPoint(GameObject pointPrefab,Vector3 pos)
        {
            if (pointPrefab == null)
            {
                Debug.LogError("The Prefab is Null!");
                return null;
            }
            if (null == m_pointParent)
                m_pointParent = new GameObject("AllPoints");
            GameObject pointClone = Instantiate(pointPrefab);
            pointClone.name = pointClone.name.Replace("(Clone)", "");
            pointClone.transform.SetParent(m_pointParent.transform);
            pointClone.transform.position = pos;

            return pointClone;
        }

        //贝塞尔曲线公式：B(t)=P0*(1-t)^3 + 3*P1*t(1-t)^2 + 3*P2*t^2*(1-t) + P3*t^3 ,t属于[0,1].
        Vector3 CalculateCubicBezierPoint(float t, Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3)
        {
            float u = 1 - t;
            float tt = t * t;
            float uu = u * u;
            float uuu = uu * u;
            float ttt = tt * t;

            Vector3 p = uuu * p0;
            p += 3 * uu * t * p1;
            p += 3 * u * tt * p2;
            p += ttt * p3;

            return p;
        }
    }
}

2. CurvePointControl.cs （挂载到路径点与调节点上（两个预制体））

该脚本实现每个路径点对应的两个调节点，以及绘制调节点与路径点之间的切线。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;


namespace DM.Editor.View
{
    public class CurvePointControl : MonoBehaviour
    {
        [Header("锁定X轴")]
        public bool m_isLockX = false;
        [Header("锁定Y轴")]
        public bool m_isLockY = true;
        [Header("锁定Z轴")]
        public bool m_isLockZ = false;
       
        [HideInInspector]
        public GameObject m_controlObject;
        [HideInInspector]
        public GameObject m_controlObject2;


        private Vector3 offsetPos1 = Vector3.zero;
        private Vector3 offsetPos2 = Vector3.zero;
        private LineRenderer lineRenderer;
        void Start()
        {
            if (gameObject.tag.Equals("AnchorPoint") && !lineRenderer)
                lineRenderer = gameObject.AddComponent();
            if (lineRenderer)
            {
                lineRenderer.sortingOrder = 1;
                lineRenderer.material = new Material(Shader.Find("Particles/Alpha Blended"));
                lineRenderer.startColor = lineRenderer.endColor = Color.yellow;
                lineRenderer.widthMultiplier = 0.03f;
                lineRenderer.positionCount = 0;
            }
        }
        void OnMouseDown()
        {
            if (!gameObject.tag.Equals("AnchorPoint")) return;
            OffsetPos();
        }
        public List OffsetPos()
        {
            List offsetPosList = new List();
            if (m_controlObject)
                offsetPos1 = m_controlObject.transform.position - transform.position;
            if (m_controlObject2)
                offsetPos2 = m_controlObject2.transform.position - transform.position;
            offsetPosList.Add(offsetPos1);
            offsetPosList.Add(offsetPos2);


            return offsetPosList;
        }
        void OnMouseDrag()
        {
            //if (gameObject.tag.Equals("AnchorPoint")) return;
            Vector3 pos0 = Camera.main.WorldToScreenPoint(transform.position);
            Vector3 mousePos = new Vector3(Input.mousePosition.x, Input.mousePosition.y, pos0.z);
            Vector3 mousePosInWorld= Camera.main.ScreenToWorldPoint(mousePos);
            Vector3 thisPos = mousePosInWorld;
            if (m_isLockX)
                thisPos.x = transform.position.x;
            if (m_isLockY)
                thisPos.y = transform.position.y;
            if (m_isLockZ)
                thisPos.z = transform.position.z;
            transform.position = thisPos;
            DMDrawCurve.Instance.UpdateLine(gameObject, offsetPos1, offsetPos2);   
        }      
        private void DrawControlLine()
        {
            if (!gameObject.tag.Equals("AnchorPoint") || (!m_controlObject && !m_controlObject2)) return;
            if (lineRenderer)
            {
                lineRenderer.positionCount = (m_controlObject && m_controlObject2) ? 3 : 2;
                if (m_controlObject && !m_controlObject2)
                {
                    lineRenderer.SetPosition(0, m_controlObject.transform.position);
                    lineRenderer.SetPosition(1, transform.position);
                }
                if (m_controlObject2 && !m_controlObject)
                {
                    lineRenderer.SetPosition(0, transform.position);
                    lineRenderer.SetPosition(1, m_controlObject2.transform.position);
                }
                if (m_controlObject && m_controlObject2)
                {
                    lineRenderer.SetPosition(0, m_controlObject.transform.position);
                    lineRenderer.SetPosition(1, transform.position);
                    lineRenderer.SetPosition(2, m_controlObject2.transform.position);
                }
            }
        }
        void Update()
        {
            DrawControlLine();
        }
    }
}

对应Inspector，如图

3. Test.cs （任意挂载）

该脚本实现Player自动寻路。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace DM.Editor.View
{
    public class Test : MonoBehaviour
    {
        public GameObject m_player;
        public List m_pathPoints;
        void Start()
        {
            DMDrawCurve.Instance.Init(m_player);
        }

        IEnumerator Move()
        {
            if (m_pathPoints.Count == 0) yield break;
            int item = 1;
            while (true)
            {
                m_player.transform.LookAt(m_pathPoints[item]);
                m_player.transform.position = Vector3.Lerp(m_pathPoints[item - 1], m_pathPoints[item], 1f);
                item++;
                if (item >= m_pathPoints.Count)
                {
                    item = 1;
                    yield break;
                }
                yield return new WaitForEndOfFrame();
            }
        }
        void Update()
        {
            if (Input.GetKey(KeyCode.LeftControl) && (Input.GetMouseButtonUp(0) || Input.GetMouseButtonUp(1)))
            {
                Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
                RaycastHit hit;
                if (Physics.Raycast(ray, out hit))
                {
                    if (Input.GetMouseButtonUp(0) && hit.collider.tag.Equals("Terrain"))
                    {
                        Vector3 pointPos = new Vector3(hit.point.x, m_player.transform.position.y, hit.point.z);
                        DMDrawCurve.Instance.AddPoint(pointPos);
                    }
                    else if (Input.GetMouseButtonUp(1) && hit.collider.tag.Equals("AnchorPoint"))
                    {
                        DMDrawCurve.Instance.DeletePoint(hit.collider.gameObject);
                    }
                }
            }
            if (Input.GetKeyUp(KeyCode.A))
                m_pathPoints = DMDrawCurve.Instance.HiddenLine(false);
            else if (Input.GetKeyUp(KeyCode.Escape))
            {
                DMDrawCurve.Instance.HiddenLine(true);
                m_pathPoints.Clear();
            }
            if (Input.GetKeyUp(KeyCode.B))
            {
                StartCoroutine(Move());
            }
        }
    }
}

注意：需要添加两个Tag值(Terrain，AnchorPoint)，也可动态添加，一个给场景地面，一个给路径点（AnchorPoint），调节点不需要Tag。

开发测试Demo以及.unitypackage的网盘链接如下，需要的自行下载：

链接：https://pan.baidu.com/s/1dwIOxcMB-Lhq_Tlxenb4fQ 密码：7g8y

以上就是近日开发结果，如有不足，请批评指正。如有疑问，请留言，看到自然回复。

如转载，请注明出处：IT_yanghui的博客