新增box复合体 修复vector2运算问题

source/src/Math/Vector2.ts

@@ -3,17 +3,6 @@ class Vector2 {
     public x: number = 0;
     public y: number = 0;
 
-    private static readonly zeroVector = new Vector2(0, 0);
-    private static readonly unitVector = new Vector2(1, 1);
-
-    public static get One(){
-        return this.unitVector;
-    }
-
-    public static get Zero(){
-        return this.zeroVector;
-    }
-
     /**
      * 从两个值构造一个带有X和Y的二维向量。
      * @param x 二维空间中的x坐标
@@ -25,26 +14,30 @@ class Vector2 {
     }
 
     public static add(value1: Vector2, value2: Vector2){
-        value1.x += value2.x;
-        value1.y += value2.y;
-        return value1;
+        let result: Vector2 = new Vector2(0, 0);
+        result.x = value1.x + value2.x;
+        result.y = value1.y + value2.y;
+        return result;
     }
 
     public static divide(value1: Vector2, value2: Vector2){
-        value1.x /= value2.x;
-        value1.y /= value2.y;
+        let result: Vector2 = new Vector2(0, 0);
+        result.x = value1.x / value2.x;
+        result.y = value1.y / value2.y;
         return value1;
     }
 
     public static multiply(value1: Vector2, value2: Vector2){
-        value1.x *= value2.x;
-        value1.y *= value2.y;
-        return value1;
+        let result: Vector2 = new Vector2(0, 0);
+        result.x = value1.x * value2.x;
+        result.y = value1.y * value2.y;
+        return result;
     }
 
     public static subtract(value1: Vector2, value2: Vector2){
-        value1.x -= value2.x;
-        value1.y -= value2.y;
+        let result: Vector2 = new Vector2(0, 0);
+        result.x = value1.x - value2.x;
+        result.y = value1.y - value2.y;
         return value1;
     }
 
@@ -55,6 +48,10 @@ class Vector2 {
         this.y *= val;
     }
 
+    public length(){
+        return Math.sqrt((this.x * this.x) + (this.y * this.y));
+    }
+
     /**
      * 返回两个向量的点积
      * @param value1 
@@ -77,4 +74,9 @@ class Vector2 {
     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));
     }
+
+    public static distance(value1: Vector2, value2: Vector2){
+        let v1 = value1.x - value2.x, v2 = value1.y - value2.y;
+        return Math.sqrt((v1 * v1) + (v2 * v2));
+    }
 }