用javascript 面向对象制作坦克大战（三）

 1 // 碰撞检测对象 继承自顶级对象
 2 HitTestObject = function () { }
 3 
 4 HitTestObject.prototype = new TankObject();
 5 // 碰撞检测 参数为地图对象 返回true则不能移动
 6 HitTestObject.prototype.HitTest = function (battleField) {
 7 
 8     var nextObj = this.GetNextBattleFieldCell(battleField);
 9     if (nextObj == null) {
10         return true;// 场景越界
11     }
12     // 检测是否是障碍物
13     if (nextObj.obj instanceof Barrier) {
14 
15         if (nextObj.obj instanceof EmptyB) {
16             // 判断是否被其他坦克占用  Tank继承自Mover
17             return nextObj.occupier instanceof Mover;
18         }
19         return !nextObj.obj.CanAcross;
20     }
21 
22 
23 }
24 
25 // 返回对象移动下个位置的地图对象
26 HitTestObject.prototype.GetNextBattleFieldCell = function (battleField) {
27 
28     if (this.Direction == EnumDirection.Up && this.YPosition == 0 ||
29         this.Direction == EnumDirection.Down && this.YPosition == 12 ||
30         this.Direction == EnumDirection.Left && this.XPosition == 0 ||
31         this.Direction == EnumDirection.Right && this.XPosition == 12
32         ) {
33         return null;/* 场景越界 */
34     }
35 
36     var y = this.YPosition;
37     var x = this.XPosition;
38     var nextAxes = this.GetNextAxes(x, y);
39     return battleField[nextAxes.y][nextAxes.x];
40 }
41 
42 // 得到对象的下个位置的坐标
43 HitTestObject.prototype.GetNextAxes = function (x, y) {
44     var point = { x: x, y: y };
45     switch (this.Direction + "") {    // 加空字符转换为字符串类型
46         case EnumDirection.Up:
47             point.y--; break;
48         case EnumDirection.Right:
49             point.x++; break;
50         case EnumDirection.Down:
51             point.y++; break;
52         case EnumDirection.Left:
53             point.x--; break;
54     }
55     return point;
56 }
57 
58 
59 HitTestObject.prototype.OnHitTest = function (battleField) {
60     //  预留给炮弹对象重写
61 }

 1 //  炮弹对象,这个对象需要放在TANK对象前面，有先后顺序
 2 Bomb = function () {
 3     this.Owner = null;
 4     this.Power = 1;
 5     this.Speed = 7;
 6 }
 7 
 8 Bomb.prototype = new Mover();
 9 Bomb.prototype.Load = function (x,y) {
10     // 创建炮弹对象，初始化位置
11     this.UI = UtilityClass.CreateE("div", "", "bomb", document.getElementById("divMap"))
12     this.SetPosition(x * 40, y * 40);   /*父类方法*/
13 
14 }
15 
16 // 重写HitTest方法
17 Bomb.prototype.HitTest = function (battleField) {
18     var nextObj = this.GetNextBattleFieldCell(battleField);
19     if (nextObj == null) {
20         return true;
21     }
22     // 检测是否是障碍物
23     if (nextObj.obj instanceof Barrier) {
24         // 河流穿过
25         if (this instanceof Bomb && nextObj.obj instanceof RiverB) {
26             return false;
27         }
28 
29         return !nextObj.obj.CanAcross;
30     }
31 
32 }
33 
34 // 重写OnHitTest方法 当炮弹碰撞到不可穿过对象时调用
35 Bomb.prototype.OnHitTest = function (battleField) {
36 
37     // 播放爆炸效果
38     var ex = new Explode();
39     ex.Play(this.XPosition, this.YPosition);
40     this.Owner.BombUsed--;      /*已用弹药数减一*/
41     // 清空地图占有位置，移除元素
42     battleField[this.YPosition][this.XPosition].occupier = null;
43     UtilityClass.RemoveE(this.UI, document.getElementById("divMap"));
44 
45     var nextObj = this.GetNextBattleFieldCell(battleField);
46     if (nextObj == null) { return; }
47     // 炮弹打到了障碍物
48     if (nextObj.obj instanceof Barrier) {
49         if (nextObj.obj.CanBeAttacked) {
50             nextObj.obj.DefenVal -= this.Power;
51             // 障碍物防御值降到0，把障碍物变为空地
52             if (nextObj.obj.DefenVal <= 0) {
53                 var to = new EmptyB();
54                 to.UI = nextObj.obj.UI;
55                 to.XPosition = nextObj.obj.XPosition;
56                 to.YPosition = nextObj.obj.YPosition;
57                 nextObj.obj = to;
58                 to.UI.className = "";
59                 battleField[this.YPosition][this.XPosition].obj.UI.className = "";
60             }
61         }
62     }
63         
64 }