init

.gitignore

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+# This .gitignore file should be placed at the root of your Unity project directory
+#
+# Get latest from https://github.com/github/gitignore/blob/master/Unity.gitignore
+#
+/[Ll]ibrary/
+/[Tt]emp/
+/[Oo]bj/
+/[Bb]uild/
+/[Bb]uilds/
+/[Ll]ogs/
+/[Mm]emoryCaptures/
+/[Cc]apture*/
+
+# Never ignore Asset meta data
+!/[Aa]ssets/**/*.meta
+
+# Uncomment this line if you wish to ignore the asset store tools plugin
+# /[Aa]ssets/AssetStoreTools*
+
+# Autogenerated Jetbrains Rider plugin
+[Aa]ssets/Plugins/Editor/JetBrains*
+
+# Visual Studio cache directory
+.vs/
+
+# Gradle cache directory
+.gradle/
+
+# Autogenerated VS/MD/Consulo solution and project files
+ExportedObj/
+.consulo/
+*.csproj
+*.unityproj
+*.sln
+*.suo
+*.tmp
+*.user
+*.userprefs
+*.pidb
+*.booproj
+*.svd
+*.pdb
+*.mdb
+*.opendb
+*.VC.db
+
+# Unity3D generated meta files
+*.pidb.meta
+*.pdb.meta
+*.mdb.meta
+
+# Unity3D generated file on crash reports
+sysinfo.txt
+
+# Builds
+*.apk
+*.unitypackage
+
+# Crashlytics generated file
+crashlytics-build.properties

Assets/Boids/Boids.cs

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+using System.Collections;
+using System.Collections.Generic;
+using Unity.Collections;
+using Unity.Mathematics;
+using UnityEngine;
+using UnityEngine.Jobs;
+using Unity.Jobs;
+using Unity.Burst;
+using Random = Unity.Mathematics.Random;
+
+public class Boids : MonoBehaviour {
+
+    #region Job
+    [BurstCompile]
+    struct UpdateMove : IJobParallelForTransform {
+        public NativeArray<Vector3> position;
+        public NativeArray<Vector3> velocity;
+        public NativeArray<Vector3> accel;
+        public Vector2 limit;
+        public float dt;
+
+        void IJobParallelForTransform.Execute(int id, TransformAccess t) {
+            var vel = velocity[id] + accel[id] * dt;
+            var dir = Vector3.Normalize(vel);
+            var mag = Vector3.Magnitude(vel);
+            vel = math.clamp(mag, limit.x, limit.y) * dir;
+            t.position += vel * dt;
+            t.rotation = Quaternion.LookRotation(dir);
+            accel[id] = Vector3.zero;
+            position[id] = t.position;
+            velocity[id] = vel;
+        }
+    }
+
+    [BurstCompile]
+    struct UpdateWall : IJobParallelFor {
+        [ReadOnly] public NativeArray<Vector3> position;
+        public NativeArray<Vector3> accel;
+        public Vector3 scale;
+
+        public void Execute(int id) {
+            var p = position[id];
+            var s = scale * 0.5f;
+            accel[id] += Condition(-s.x - p.x, Vector3.right) +
+                         Condition(-s.y - p.y, Vector3.up) +
+                         Condition(-s.z - p.z, Vector3.forward) +
+                         Condition(+s.x - p.x, Vector3.left) +
+                         Condition(+s.y - p.y, Vector3.down) +
+                         Condition(+s.z - p.z, Vector3.back);
+        }
+
+        Vector3 Condition(float dst, Vector3 dir) {
+            var threshold = 3f;
+            var weight = 2f;
+            var d = math.abs(dst);
+            return d < threshold ? dir * (weight / (d / threshold)) : Vector3.zero;
+        }
+    }
+
+    [BurstCompile]
+    struct UpdateSmlt : IJobParallelFor {
+        [ReadOnly]  public NativeArray<Vector3> position;
+        [ReadOnly]  public NativeArray<Vector3> velocity;
+        public NativeArray<Vector3> accel;
+        public Vector3 weights;
+        public float dstThreshold;
+        int n => position.Length;
+
+        public void Execute(int id) {
+            Vector3 avgSpr = Vector3.zero,
+                    avgVel = Vector3.zero,
+                    avgPos = Vector3.zero,
+                    pos    = position[id],
+                    vel    = velocity[id];
+
+            for (int j = 0; j < n; j++) {
+                if (j == id) continue;
+                var tgtPos = position[j];
+                var tgtVel = velocity[j];
+                var tgtDif = pos - tgtPos;
+                if (tgtDif.magnitude < dstThreshold) {
+                    avgSpr += tgtDif.normalized;
+                    avgVel += tgtVel;
+                    avgPos += tgtPos;
+                }
+            }
+            accel[id] += (avgSpr * weights.x + avgVel * weights.y + avgPos * weights.z) / n;
+        }
+    }
+
+    [Unity.Burst.BurstCompile]
+    struct CountJob : IJob {
+        public NativeArray<Vector3> position;
+        public NativeArray<int> result;
+        int n => position.Length;
+
+        public void Execute() {
+            result[0] = 0;
+            for (int i = 0; i < n; i++) {
+                if(position[i].x > 0) result[0] += 1;
+            }
+        }
+    }
+
+    #endregion
+
+    [SerializeField] protected int num;
+    [SerializeField] protected GameObject prefab; 
+    [SerializeField] protected Vector3 areaSize;
+    [SerializeField] protected float distThreshold;
+    [SerializeField] Vector2 velThreshold;
+    [SerializeField] Vector3 simWeight;
+    protected Transform[] objs;
+    protected NativeArray<Vector3> pos, vel, acc;
+    protected TransformAccessArray trs;
+    protected NativeArray<Random>  rnd;
+    protected NativeArray<int> rst;
+    protected Random seed;
+
+    void Start() {
+        objs = new Transform[num];
+        for (int i = 0; i < num; i++) {
+            var obj = Instantiate(prefab).transform;
+            obj.position = Vector3.zero;
+            objs[i] = obj;
+        }
+
+        pos = new NativeArray<Vector3>(num, Allocator.Persistent);
+        vel = new NativeArray<Vector3>(num, Allocator.Persistent);
+        acc = new NativeArray<Vector3>(num, Allocator.Persistent);
+        trs = new TransformAccessArray(objs);
+        rst = new NativeArray<int>(1, Allocator.Persistent);
+        rnd = new NativeArray<Random>(num, Allocator.Persistent);
+
+        for (int i = 0; i < num; i++) {
+            pos[i] = Vector3.zero;
+            vel[i] = UnityEngine.Random.insideUnitSphere;
+            acc[i] = Vector3.zero;
+        }
+        seed = new Random(1);
+    }
+
+    void Update() {
+        for (int i = 0; i < num; i++) rnd[i] = new Random(seed.NextUInt());
+        var jobWall = new UpdateWall { position = pos, accel = acc, scale = areaSize};
+        var jobSmlt = new UpdateSmlt { position = pos, velocity = vel, accel = acc, dstThreshold = distThreshold, weights = simWeight};
+        var jobMove = new UpdateMove { position = pos, velocity = vel, accel = acc, dt = Time.deltaTime, limit = velThreshold};
+        var handlerWall = jobWall.Schedule(num, 0);
+        var handlerSmlt = jobSmlt.Schedule(num, 0, handlerWall);
+        var handlerMove = jobMove.Schedule(trs, handlerSmlt);
+        handlerMove.Complete();
+    }
+
+    void OnDrawGizmos() {
+        Gizmos.DrawWireCube(Vector3.zero, areaSize);
+    }
+    void OnGUI() {
+    }
+
+    void OnDestroy() {
+        pos.Dispose();
+        vel.Dispose();
+        acc.Dispose();
+        trs.Dispose();
+        rst.Dispose();
+        rnd.Dispose();
+    }
+}

Assets/Boids/Cube.prefab

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