diff --git a/source/src/ECS/Entity.ts b/source/src/ECS/Entity.ts
index 4c61fe85..03e2911b 100644
--- a/source/src/ECS/Entity.ts
+++ b/source/src/ECS/Entity.ts
@@ -1,5 +1,8 @@
 class Entity {
+    private static _idGenerator: number;
+
     public name: string;
+    public readonly id: number;
     /** 当前实体所属的场景 */
     public scene: Scene;
     /** 封装实体的位置/旋转/缩放，并允许设置一个高层结构 */
@@ -9,6 +12,7 @@ class Entity {
     private _updateOrder: number = 0;
     private _enabled: boolean = true;
     private _isDestoryed: boolean;
+    private _tag: number = 0;
 
     public componentBits: BitSet;
 
@@ -116,10 +120,20 @@ class Entity {
         return this;
     }
 
+    public get tag(){
+        return this._tag;
+    }
+
+    public set tag(value: number){
+        this.setTag(value);
+    }
+
     constructor(name: string){
         this.name = name;
         this.transform = new Transform(this);
         this.components = new ComponentList(this);
+        this.id = Entity._idGenerator ++;
+
         this.componentBits = new BitSet();
     }
 
@@ -142,6 +156,20 @@ class Entity {
         }
     }
 
+    public setTag(tag: number): Entity{
+        if (this._tag != tag){
+            if (this.scene){
+                this.scene.entities.removeFromTagList(this);
+            }
+            this._tag = tag;
+            if (this.scene){
+                this.scene.entities.addToTagList(this);
+            }
+        }
+
+        return this;
+    }
+
     public attachToScene(newScene: Scene){
         this.scene = newScene;
         newScene.entities.add(this);
diff --git a/source/src/ECS/Utils/EntityList.ts b/source/src/ECS/Utils/EntityList.ts
index d3e20f73..5e19ceb2 100644
--- a/source/src/ECS/Utils/EntityList.ts
+++ b/source/src/ECS/Utils/EntityList.ts
@@ -4,6 +4,8 @@ class EntityList{
     private _entitiesToAdded: Entity[] = [];
     private _tempEntityList: Entity[] = [];
     private _entities: Entity[] = [];
+    private _entityDict: Map<number, Entity[]> = new Map<number, Entity[]>();
+    private _unsortedTags: number[] = [];
 
     constructor(scene: Scene){
         this.scene = scene;
@@ -40,6 +42,31 @@ class EntityList{
         return this._entitiesToAdded.firstOrDefault(entity => entity.name == name);
     }
 
+    public getTagList(tag: number){
+        let list = this._entityDict.get(tag);
+        if (!list){
+            list = [];
+            this._entityDict.set(tag, list);
+        }
+
+        return this._entityDict.get(tag);
+    }
+
+    public addToTagList(entity: Entity){
+        let list = this.getTagList(entity.tag);
+        if (!list.contains(entity)){
+            list.push(entity);
+            this._unsortedTags.push(entity.tag);
+        }
+    }
+
+    public removeFromTagList(entity: Entity){
+        let list = this._entityDict.get(entity.tag);
+        if (list){
+            list.remove(entity);
+        }
+    }
+
     public update(){
         for (let i = 0; i < this._entities.length; i++){
             let entity = this._entities[i];
@@ -58,6 +85,7 @@ class EntityList{
         }
 
         this._entities.length = 0;
+        this._entityDict.clear();
     }
 
     public updateLists(){
@@ -89,5 +117,13 @@ class EntityList{
             this._tempEntityList.forEach(entity => entity.onAddedToScene());
             this._tempEntityList.length = 0;
         }
+
+        if (this._unsortedTags.length > 0){
+            this._unsortedTags.forEach(tag => {
+                this._entityDict.get(tag).sort();
+            });
+
+            this._unsortedTags.length = 0;
+        }
     }
 }
\ No newline at end of file
diff --git a/source/src/Math/Rectangle.ts b/source/src/Math/Rectangle.ts
new file mode 100644
index 00000000..d88cdb9a
--- /dev/null
+++ b/source/src/Math/Rectangle.ts
@@ -0,0 +1,13 @@
+class Rectangle {
+    public x: number;
+    public y: number;
+    public width: number;
+    public height: number;
+
+    constructor(x: number, y: number, width: number, height: number){
+        this.x = x;
+        this.y = y;
+        this.width = width;
+        this.height = height;
+    }
+}
\ No newline at end of file
diff --git a/source/src/Math/Vector2.ts b/source/src/Math/Vector2.ts
index 15ea5983..438e66d7 100644
--- a/source/src/Math/Vector2.ts
+++ b/source/src/Math/Vector2.ts
@@ -3,10 +3,15 @@ class Vector2 {
     public x: number = 0;
     public y: number = 0;
 
-    private static readonly unitVector2 = new Vector2(1, 1);
+    private static readonly zeroVector = new Vector2(0, 0);
+    private static readonly unitVector = new Vector2(1, 1);
 
     public static get One(){
-        return this.unitVector2;
+        return this.unitVector;
+    }
+
+    public static get Zero(){
+        return this.zeroVector;
     }
 
     /**
@@ -50,6 +55,25 @@ class Vector2 {
         this.y *= val;
     }
 
+    /**
+     * 返回两个向量的点积
+     * @param value1 
+     * @param value2 
+     */
+    public static dot(value1: Vector2, value2: Vector2): number{
+        return (value1.x * value2.x) + (value1.y * value2.y);
+    }
+
+    /**
+     * 返回两个向量之间距离的平方
+     * @param value1 
+     * @param value2 
+     */
+    public static distanceSquared(value1: Vector2, value2: Vector2){
+        let v1 = value1.x - value2.x, v2 = value1.y - value2.y;
+        return (v1 * v1) + (v2 * v2);
+    }
+
     public static transform(position: Vector2, matrix: Matrix2D){
         return new Vector2((position.x * matrix.m11) + (position.y * matrix.m21), (position.x * matrix.m12) + (position.y * matrix.m22));
     }
diff --git a/source/src/Physics/Collision.ts b/source/src/Physics/Collision.ts
new file mode 100644
index 00000000..bef32cbb
--- /dev/null
+++ b/source/src/Physics/Collision.ts
@@ -0,0 +1,198 @@
+enum PointSectors {
+    center = 0,
+    top = 1,
+    bottom = 2,
+    topLeft = 9,
+    topRight = 5,
+    left = 8,
+    right = 4,
+    bottomLeft = 10,
+    bottomRight = 6
+}
+
+class Collisions {
+    public static isLineToLine(a1: Vector2, a2: Vector2, b1: Vector2, b2: Vector2): boolean {
+        let b = Vector2.subtract(a2, a1);
+        let d = Vector2.subtract(b2, b1);
+        let bDotDPerp = b.x * d.y - b.y * d.x;
+
+        // 如果b*d = 0，表示这两条直线平行，因此有无穷个交点
+        if (bDotDPerp == 0)
+            return false;
+
+        let c = Vector2.subtract(b1, a1);
+        let t = (c.x * d.y - c.y * d.x) / bDotDPerp;
+        if (t < 0 || t > 1)
+            return false;
+
+        let u = (c.x * b.y - c.y * b.x) / bDotDPerp;
+        if (u < 0 || u > 1)
+            return false;
+
+        return true;
+    }
+
+    public static lineToLineIntersection(a1: Vector2, a2: Vector2, b1: Vector2, b2: Vector2): Vector2 {
+        let intersection = Vector2.Zero;
+
+        let b = Vector2.subtract(a2, a1);
+        let d = Vector2.subtract(b2, b1);
+        let bDotDPerp = b.x * d.y - b.y * d.x;
+
+        // 如果b*d = 0，表示这两条直线平行，因此有无穷个交点
+        if (bDotDPerp == 0)
+            return intersection;
+
+        let c = Vector2.subtract(b1, a1);
+        let t = (c.x * d.y - c.y * d.x) / bDotDPerp;
+        if (t < 0 || t > 1)
+            return intersection;
+
+        let u = (c.x * b.y - c.y * b.x) / bDotDPerp;
+        if (u < 0 || u > 1)
+            return intersection;
+
+        intersection = Vector2.add(a1, new Vector2(t * b.x, t * b.y));
+
+        return intersection;
+    }
+
+    public static closestPointOnLine(lineA: Vector2, lineB: Vector2, closestTo: Vector2) {
+        let v = Vector2.subtract(lineB, lineA);
+        let w = Vector2.subtract(closestTo, lineA);
+        let t = Vector2.dot(w, v) / Vector2.dot(v, v);
+        t = MathHelper.clamp(t, 0, 1);
+
+        return Vector2.add(lineA, new Vector2(v.x * t, v.y * t));
+    }
+
+    public static isCircleToCircle(circleCenter1: Vector2, circleRadius1: number, circleCenter2: Vector2, circleRadius2: number): boolean {
+        return Vector2.distanceSquared(circleCenter1, circleCenter2) < (circleRadius1 + circleRadius2) * (circleRadius1 + circleRadius2);
+    }
+
+    public static isCircleToLine(circleCenter: Vector2, radius: number, lineFrom: Vector2, lineTo: Vector2): boolean {
+        return Vector2.distanceSquared(circleCenter, this.closestPointOnLine(lineFrom, lineTo, circleCenter)) < radius * radius;
+    }
+
+    public static isCircleToPoint(circleCenter: Vector2, radius: number, point: Vector2): boolean {
+        return Vector2.distanceSquared(circleCenter, point) < radius * radius;
+    }
+
+    public static isRectToCircle(rect: Rectangle, cPosition: Vector2, cRadius: number): boolean {
+        if (this.isRectToPoint(rect.x, rect.y, rect.width, rect.height, cPosition))
+            return true;
+
+        let edgeFrom: Vector2;
+        let edgeTo: Vector2;
+        let sector = this.getSector(rect.x, rect.y, rect.width, rect.height, cPosition);
+
+        if ((sector & PointSectors.top) != 0) {
+            edgeFrom = new Vector2(rect.x, rect.y);
+            edgeTo = new Vector2(rect.x + rect.width, rect.y);
+            if (this.isCircleToLine(cPosition, cRadius, edgeFrom, edgeTo))
+                return true;
+        }
+
+        if ((sector & PointSectors.bottom) != 0) {
+            edgeFrom = new Vector2(rect.x, rect.y + rect.height);
+            edgeTo = new Vector2(rect.x + rect.width, rect.y + rect.height);
+            if (this.isCircleToLine(cPosition, cRadius, edgeFrom, edgeTo))
+                return true;
+        }
+
+        if ((sector & PointSectors.left) != 0) {
+            edgeFrom = new Vector2(rect.x, rect.y);
+            edgeTo = new Vector2(rect.x, rect.y + rect.height);
+            if (this.isCircleToLine(cPosition, cRadius, edgeFrom, edgeTo))
+                return true;
+        }
+
+        if ((sector & PointSectors.right) != 0) {
+            edgeFrom = new Vector2(rect.x + rect.width, rect.y);
+            edgeTo = new Vector2(rect.x + rect.width, rect.y + rect.height);
+            if (this.isCircleToLine(cPosition, cRadius, edgeFrom, edgeTo))
+                return true;
+        }
+
+        return false;
+    }
+
+    public static isRectToLine(rect: Rectangle, lineFrom: Vector2, lineTo: Vector2){
+        let fromSector = this.getSector(rect.x, rect.y, rect.width, rect.height, lineFrom);
+        let toSector = this.getSector(rect.x, rect.y, rect.width, rect.height, lineTo);
+
+        if (fromSector == PointSectors.center || toSector == PointSectors.center){
+            return true;
+        } else if((fromSector & toSector) != 0){
+            return false;
+        } else{
+            let both = fromSector | toSector;
+            // 线对边进行检查
+            let edgeFrom: Vector2;
+            let edgeTo: Vector2;
+
+            if ((both & PointSectors.top) != 0){
+                edgeFrom = new Vector2(rect.x, rect.y);
+                edgeTo = new Vector2(rect.x + rect.width, rect.y);
+                if (this.isLineToLine(edgeFrom, edgeTo, lineFrom, lineTo))
+                    return true;
+            }
+
+            if ((both & PointSectors.bottom) != 0){
+                edgeFrom = new Vector2(rect.x, rect.y + rect.height);
+                edgeTo = new Vector2(rect.x + rect.width, rect.y + rect.height);
+                if (this.isLineToLine(edgeFrom, edgeTo, lineFrom, lineTo))
+                    return true;
+            }
+
+            if ((both & PointSectors.left) != 0){
+                edgeFrom = new Vector2(rect.x, rect.y);
+                edgeTo = new Vector2(rect.x, rect.y + rect.height);
+                if (this.isLineToLine(edgeFrom, edgeTo, lineFrom, lineTo))
+                    return true;
+            }
+
+            if ((both & PointSectors.right) != 0){
+                edgeFrom = new Vector2(rect.x + rect.width, rect.y);
+                edgeTo = new Vector2(rect.x + rect.width, rect.y + rect.height);
+                if (this.isLineToLine(edgeFrom, edgeTo, lineFrom, lineTo))
+                    return true;
+            }
+        }
+
+        return false;
+    }
+
+    public static isRectToPoint(rX: number, rY: number, rW: number, rH: number, point: Vector2) {
+        return point.x >= rX && point.y >= rY && point.x < rX + rW && point.y < rY + rH;
+    }
+
+    /**
+     * 位标志和帮助使用Cohen–Sutherland算法
+     * 
+     * 位标志:
+     * 1001 1000 1010
+     * 0001 0000 0010
+     * 0101 0100 0110
+     * @param rX 
+     * @param rY 
+     * @param rW 
+     * @param rH 
+     * @param point 
+     */
+    public static getSector(rX: number, rY: number, rW: number, rH: number, point: Vector2): PointSectors {
+        let sector = PointSectors.center;
+
+        if (point.x < rX)
+            sector |= PointSectors.left;
+        else if (point.x >= rX + rW)
+            sector |= PointSectors.right;
+
+        if (point.y < rY)
+            sector |= PointSectors.top;
+        else if (point.y >= rY + rH)
+            sector |= PointSectors.bottom;
+
+        return sector;
+    }
+}
\ No newline at end of file