unity的自动寻路之 ------ wayPoint寻路的实现方式

孙广东 2015.6.28

看了看  Unity的官方案例，就顺便看了 wayPoint相关。

效果：

WaypointProgressTracker.cs  【固定】

WaypointCircuit.cs  【固定】

using System;
using System.Collections;
using UnityEngine;
#if UNITY_EDITOR
using UnityEditor;

#endif

namespace UnityStandardAssets.Utility
{
    public class WaypointCircuit : MonoBehaviour
    {
        public WaypointList waypointList = new WaypointList();
        [SerializeField] private bool smoothRoute = true;
        private int numPoints;
        private Vector3[] points;
        private float[] distances;

        public float editorVisualisationSubsteps = 100;
        public float Length { get; private set; }

        public Transform[] Waypoints
        {
            get { return waypointList.items; }
        }

        // 这是在这里会保存 GC 分配
        private int p0n;
        private int p1n;
        private int p2n;
        private int p3n;

        private float i;
        private Vector3 P0;
        private Vector3 P1;
        private Vector3 P2;
        private Vector3 P3;

        // Use this for initialization
        private void Awake()
        {
            if (Waypoints.Length > 1)
            {
                CachePositionsAndDistances();
            }
            numPoints = Waypoints.Length;
        }


        public RoutePoint GetRoutePoint(float dist)
        {
            // 位置和方向
            Vector3 p1 = GetRoutePosition(dist);
            Vector3 p2 = GetRoutePosition(dist + 0.1f);
            Vector3 delta = p2 - p1;
            return new RoutePoint(p1, delta.normalized);
        }


        public Vector3 GetRoutePosition(float dist)
        {
            int point = 0;

            if (Length == 0)
            {
                Length = distances[distances.Length - 1];
            }

            dist = Mathf.Repeat(dist, Length);

            while (distances[point] < dist)
            {
                ++point;
            }


            // get nearest two points, ensuring points wrap-around start & end of circuit
			// 得到最近的两个点，确保点环绕电路的开始与结束
            p1n = ((point - 1) + numPoints)%numPoints;
            p2n = point;

            // found point numbers, now find interpolation value between the two middle points
			// 发现点的数目，现在找到中间两点之间内的一个插值
            i = Mathf.InverseLerp(distances[p1n], distances[p2n], dist);

            if (smoothRoute)
            {
                // 有关两点之间的光滑catmull-rom计算。


                // 获取周围的 2 点的指数，因为catmull-rom 函数要求四个点
                p0n = ((point - 2) + numPoints)%numPoints;
                p3n = (point + 1)%numPoints;

                // 第二个点可能已经是最后的 'last' 点了 - a dupe of the first,
                // (to give a value of max track distance instead of zero)
                // but now it must be wrapped back to zero if that was the case.
                p2n = p2n%numPoints;

                P0 = points[p0n];
                P1 = points[p1n];
                P2 = points[p2n];
                P3 = points[p3n];

                return CatmullRom(P0, P1, P2, P3, i);
            }
            else
            {
                // 两个点之间的简单线性插值:

                p1n = ((point - 1) + numPoints)%numPoints;
                p2n = point;

                return Vector3.Lerp(points[p1n], points[p2n], i);
            }
        }


        private Vector3 CatmullRom(Vector3 p0, Vector3 p1, Vector3 p2, Vector3 p3, float i)
        {
            // 这是 catmull-rom 方程
            // Un-magic this, lord vector!
            return 0.5f*
                   ((2*p1) + (-p0 + p2)*i + (2*p0 - 5*p1 + 4*p2 - p3)*i*i +
                    (-p0 + 3*p1 - 3*p2 + p3)*i*i*i);
        }


        private void CachePositionsAndDistances()
        {
            // transfer the position of each point and distances between points to arrays for
            // speed of lookup at runtime
			// 在运行时查找到阵列速度点之间传输的每个点和距离的位置
            points = new Vector3[Waypoints.Length + 1];
            distances = new float[Waypoints.Length + 1];

            float accumulateDistance = 0;
            for (int i = 0; i < points.Length; ++i)
            {
                var t1 = Waypoints[(i)%Waypoints.Length];
                var t2 = Waypoints[(i + 1)%Waypoints.Length];
                if (t1 != null && t2 != null)
                {
                    Vector3 p1 = t1.position;
                    Vector3 p2 = t2.position;
                    points[i] = Waypoints[i%Waypoints.Length].position;
                    distances[i] = accumulateDistance;
                    accumulateDistance += (p1 - p2).magnitude;
                }
            }
        }


        private void OnDrawGizmos()
        {
            DrawGizmos(false);
        }


        private void OnDrawGizmosSelected()
        {
            DrawGizmos(true);
        }


        private void DrawGizmos(bool selected)
        {
            waypointList.circuit = this;
            if (Waypoints.Length > 1)
            {
                numPoints = Waypoints.Length;

                CachePositionsAndDistances();
                Length = distances[distances.Length - 1];

                Gizmos.color = selected ? Color.yellow : new Color(1, 1, 0, 0.5f);
                Vector3 prev = Waypoints[0].position;
                if (smoothRoute)
                {
                    for (float dist = 0; dist < Length; dist += Length/editorVisualisationSubsteps)
                    {
                        Vector3 next = GetRoutePosition(dist + 1);
                        Gizmos.DrawLine(prev, next);
                        prev = next;
                    }
                    Gizmos.DrawLine(prev, Waypoints[0].position);
                }
                else
                {
                    for (int n = 0; n < Waypoints.Length; ++n)
                    {
                        Vector3 next = Waypoints[(n + 1)%Waypoints.Length].position;
                        Gizmos.DrawLine(prev, next);
                        prev = next;
                    }
                }
            }
        }


        [Serializable]
        public class WaypointList
        {
            public WaypointCircuit circuit;
            public Transform[] items = new Transform[0];
        }

        public struct RoutePoint
        {
            public Vector3 position;
            public Vector3 direction;


            public RoutePoint(Vector3 position, Vector3 direction)
            {
                this.position = position;
                this.direction = direction;
            }
        }
    }
}

/// 编辑器对 Inspector面板的定制
namespace UnityStandardAssets.Utility.Inspector
{
#if UNITY_EDITOR
    [CustomPropertyDrawer(typeof (WaypointCircuit.WaypointList))]
    public class WaypointListDrawer : PropertyDrawer
    {
        private float lineHeight = 18;
        private float spacing = 4;


        public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
        {
            EditorGUI.BeginProperty(position, label, property);

            float x = position.x;
            float y = position.y;
            float inspectorWidth = position.width;

            // 绘制 label


            // 不要缩进的子字段
            var indent = EditorGUI.indentLevel;
            EditorGUI.indentLevel = 0;

            var items = property.FindPropertyRelative("items");
            var titles = new string[] {"Transform", "", "", ""};
            var props = new string[] {"transform", "^", "v", "-"};
            var widths = new float[] {.7f, .1f, .1f, .1f};
            float lineHeight = 18;
            bool changedLength = false;
            if (items.arraySize > 0)
            {
                for (int i = -1; i < items.arraySize; ++i)
                {
                    var item = items.GetArrayElementAtIndex(i);

                    float rowX = x;
                    for (int n = 0; n < props.Length; ++n)
                    {
                        float w = widths[n]*inspectorWidth;

                        // Calculate rects
						// 计算 rects
                        Rect rect = new Rect(rowX, y, w, lineHeight);
                        rowX += w;

                        if (i == -1)
                        {
                            EditorGUI.LabelField(rect, titles[n]);
                        }
                        else
                        {
                            if (n == 0)
                            {
                                EditorGUI.ObjectField(rect, item.objectReferenceValue, typeof (Transform), true);
                            }
                            else
                            {
                                if (GUI.Button(rect, props[n]))
                                {
                                    switch (props[n])
                                    {
                                        case "-":
                                            items.DeleteArrayElementAtIndex(i);
                                            items.DeleteArrayElementAtIndex(i);
                                            changedLength = true;
                                            break;
                                        case "v":
                                            if (i > 0)
                                            {
                                                items.MoveArrayElement(i, i + 1);
                                            }
                                            break;
                                        case "^":
                                            if (i < items.arraySize - 1)
                                            {
                                                items.MoveArrayElement(i, i - 1);
                                            }
                                            break;
                                    }
                                }
                            }
                        }
                    }

                    y += lineHeight + spacing;
                    if (changedLength)
                    {
                        break;
                    }
                }
            }
            else
            {
                // add button
			    // 添加"+"按钮
                var addButtonRect = new Rect((x + position.width) - widths[widths.Length - 1]*inspectorWidth, y,
                                             widths[widths.Length - 1]*inspectorWidth, lineHeight);
                if (GUI.Button(addButtonRect, "+"))
                {
                    items.InsertArrayElementAtIndex(items.arraySize);
                }

                y += lineHeight + spacing;
            }

            // add all button
			// 添加所有按钮
            var addAllButtonRect = new Rect(x, y, inspectorWidth, lineHeight);
            if (GUI.Button(addAllButtonRect, "Assign using all child objects"))
            {
                var circuit = property.FindPropertyRelative("circuit").objectReferenceValue as WaypointCircuit;
                var children = new Transform[circuit.transform.childCount];
                int n = 0;
                foreach (Transform child in circuit.transform)
                {
                    children[n++] = child;
                }
                Array.Sort(children, new TransformNameComparer());
                circuit.waypointList.items = new Transform[children.Length];
                for (n = 0; n < children.Length; ++n)
                {
                    circuit.waypointList.items[n] = children[n];
                }
            }
            y += lineHeight + spacing;

            // rename all button
			// 重命名所有按钮
            var renameButtonRect = new Rect(x, y, inspectorWidth, lineHeight);
            if (GUI.Button(renameButtonRect, "Auto Rename numerically from this order"))
            {
                var circuit = property.FindPropertyRelative("circuit").objectReferenceValue as WaypointCircuit;
                int n = 0;
                foreach (Transform child in circuit.waypointList.items)
                {
                    child.name = "Waypoint " + (n++).ToString("000");
                }
            }
            y += lineHeight + spacing;

            // Set indent back to what it was
			// 设置缩进
            EditorGUI.indentLevel = indent;
            EditorGUI.EndProperty();
        }


        public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
        {
            SerializedProperty items = property.FindPropertyRelative("items");
            float lineAndSpace = lineHeight + spacing;
            return 40 + (items.arraySize*lineAndSpace) + lineAndSpace;
        }


        // comparer for check distances in ray cast hits
		// 比较器检查射线发射命中的距离
        public class TransformNameComparer : IComparer
        {
            public int Compare(object x, object y)
            {
                return ((Transform) x).name.CompareTo(((Transform) y).name);
            }
        }
    }
#endif
}

using System;
using UnityEngine;

namespace UnityStandardAssets.Utility
{
    public class WaypointProgressTracker : MonoBehaviour
    {
        // 此脚本可以用于任何对象，支持沿着一条路线为标志的waypoints。
		// 此脚本管理向前看沿路线的数量，并跟踪进度和圈数。

        [SerializeField] private WaypointCircuit circuit; // 一个引用关于 waypoint-based 我们应该沿着的路线

        [SerializeField] private float lookAheadForTargetOffset = 5;
        // 我们将目标，沿着路线的偏移

        [SerializeField] private float lookAheadForTargetFactor = .1f;
        // 一个倍数，增加目标与沿着线路的距离，基于当前速度

        [SerializeField] private float lookAheadForSpeedOffset = 10;
        // 前面的偏移的唯一路线速度调整(作为waypoint目标的rotation变换)

        [SerializeField] private float lookAheadForSpeedFactor = .2f;
        // 一个倍数，沿着路线调整速度添加距离

        [SerializeField] private ProgressStyle progressStyle = ProgressStyle.SmoothAlongRoute;
        // 进度样式：是否smoothly更新位置沿着路线(好的曲线路径)或只是正常到达每个航点。

        [SerializeField] private float pointToPointThreshold = 4;
        // 接近waypoint的阈值，一旦达到这个值，目标将切换到下一个目标地点：只用于PointToPoint模式。

        public enum ProgressStyle
        {
            SmoothAlongRoute,
            PointToPoint,
        }

        // 这些是public，由其他对象读取。让一个AI知道在哪里头！
        public WaypointCircuit.RoutePoint targetPoint { get; private set; }
        public WaypointCircuit.RoutePoint speedPoint { get; private set; }
        public WaypointCircuit.RoutePoint progressPoint { get; private set; }

        public Transform target;

        private float progressDistance; // 圆形（环形）路线的进展，平滑smooth模式中使用。
        private int progressNum; // 当前waypoint数，点对点point-to-point模式中使用。
        private Vector3 lastPosition; // 用于计算当前速度(因为我们可能没有一个刚体组件)
        private float speed; // 此对象的当前速度(从最后一帧的delta计算) 

        // 设置脚本属性
        private void Start()
        {
// 我们使用transform表示目标点，这个点被认为是为即将到来的变化的速度点。这允许此信息传递给 AI 而无需进一步依赖此组件。您可以手动创建transform设置该组件 *and* AI，然后此组件将更新它，和 AI 可以阅读它。

            if (target == null)
            {
                target = new GameObject(name + " Waypoint Target").transform;
            }

            Reset();
        }


        // 对象重置为合理的值
        public void Reset()
        {
            progressDistance = 0;
            progressNum = 0;
            if (progressStyle == ProgressStyle.PointToPoint)
            {
                target.position = circuit.Waypoints[progressNum].position;
                target.rotation = circuit.Waypoints[progressNum].rotation;
            }
        }


        private void Update()
        {
            if (progressStyle == ProgressStyle.SmoothAlongRoute)
            {
                // 确定我们目前目标的位置 (这是不同于当前的进展位置，它是一个确定值沿着前方路线的) 我们使用 lerp 作为一种随着时间的推移速度进行平滑处理的简单方式。
                if (Time.deltaTime > 0)
                {
                    speed = Mathf.Lerp(speed, (lastPosition - transform.position).magnitude/Time.deltaTime,
                                       Time.deltaTime);
                }
                target.position =
                    circuit.GetRoutePoint(progressDistance + lookAheadForTargetOffset + lookAheadForTargetFactor*speed)
                           .position;
                target.rotation =
                    Quaternion.LookRotation(
                        circuit.GetRoutePoint(progressDistance + lookAheadForSpeedOffset + lookAheadForSpeedFactor*speed)
                               .direction);


                // 得到我们的当前路线的进展
                progressPoint = circuit.GetRoutePoint(progressDistance);
                Vector3 progressDelta = progressPoint.position - transform.position;
                if (Vector3.Dot(progressDelta, progressPoint.direction) < 0)
                {
                    progressDistance += progressDelta.magnitude*0.5f;
                }

                lastPosition = transform.position;
            }
            else
            {
                // 点对点模式。 如果我们足够近，只是增加Waypoint：

                Vector3 targetDelta = target.position - transform.position;
                if (targetDelta.magnitude < pointToPointThreshold)
                {
                    progressNum = (progressNum + 1)%circuit.Waypoints.Length;
                }


                target.position = circuit.Waypoints[progressNum].position;
                target.rotation = circuit.Waypoints[progressNum].rotation;

                // 得到我们的当前路线的进展
                progressPoint = circuit.GetRoutePoint(progressDistance);
                Vector3 progressDelta = progressPoint.position - transform.position;
                if (Vector3.Dot(progressDelta, progressPoint.direction) < 0)
                {
                    progressDistance += progressDelta.magnitude;
                }
                lastPosition = transform.position;
            }
        }


        private void OnDrawGizmos()
        {
            if (Application.isPlaying)
            {
                Gizmos.color = Color.green;
                Gizmos.DrawLine(transform.position, target.position);
                Gizmos.DrawWireSphere(circuit.GetRoutePosition(progressDistance), 1);
                Gizmos.color = Color.yellow;
                Gizmos.DrawLine(target.position, target.position + target.forward);
            }
        }
    }
}

最后： 看看Unity5的 sample中的 Car 和 飞机 的AI案例中：