8.弹幕系统
弹幕系统概述：
弹幕系统的设计体现了射击游戏的基本要素，玩家要在敌人放出的大量子弹（弹幕）的细小空隙间闪避，能在玩家闪躲弹幕的时候给玩家带来快感，接近满屏的子弹，增加了对玩家的视觉冲击力。
弹幕系统原理：
每一个敌机都持有一个弹幕实例，每个弹幕实例中包含多个子弹实例，通过配置弹幕的属性，使每个子弹实例在轨迹管理器的作用下，形成一种有规律性的直线运动，在视觉上给玩家展现出弹幕的效果。如图8-1所示。
图8-1
实现方法：
步骤1：
子弹类，定义子弹的属性和借口。
01 |
public class Bullet
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02 |
{ |
03 |
//从模板创建子弹Actor
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04 |
public void CreateActor ()
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05 |
{
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06 |
_obj = ActorManager.CreateFromTemplate(@"asset:bullet01.template",false);
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07 |
08 |
}
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09 |
10 |
//激活，显示子弹
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11 |
public void ActiveObj (Vector2 startPos)
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12 |
{
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13 |
_obj.Active();
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14 |
if (_obj.GetChildCount()>0)
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15 |
{
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16 |
_obj.GetChild(0).Active();
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17 |
}
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18 |
19 |
_obj.WorldPosition = new Vector3 (startPos.X,startPos.Y,2.0f);
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20 |
}
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21 |
22 |
//隐藏子弹
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23 |
public void DeactiveObj ()
|
24 |
{
|
25 |
_obj.Deactive();
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26 |
if (_obj.GetChildCount()>0)
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27 |
{
|
28 |
_obj.GetChild(0).Deactive();
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29 |
}
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30 |
}
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31 |
private Actor _obj = new Actor();
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32 |
private UInt32 _id;
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33 |
private UInt32 _target_id;
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34 |
private Vector2 _startPos;
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35 |
private bool _isShooted = false;
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36 |
} |
步骤2：
配置弹幕发射子弹的属性。
01 |
public class Barrage
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02 |
{
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03 |
//发射子弹
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04 |
public void ShootBullet (float elapsedTime, Vector3 pos)
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05 |
{
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06 |
timer += elapsedTime;
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07 |
if (timer >= _shoot_interval && _needshoot_id <= (Bullets.Count - 1))
|
08 |
{
|
09 |
Vector2 posV2 = new Vector2(pos.X,pos.Y);
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10 |
Bullets[_needshoot_id].ActiveObj(posV2);
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11 |
Bullets[_needshoot_id].SetShooted(true);
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12 |
_needshoot_id ++;
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13 |
timer = 0.0f;
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14 |
}
|
15 |
private UInt32 _id;
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16 |
private UInt32 _obj_id;
|
17 |
private float _start_speed;
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18 |
private float _accel_speed;
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19 |
private float _shoot_interval;
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20 |
private float _shoot_direction;
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21 |
private float _direction_offset;
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22 |
private List< Bullet> Bullets;
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private TrajectoryType _tt ;
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24 |
private float timer = 0.0f;
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25 |
private int _needshoot_id = 0;
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26 |
private Actor _owner;
|
27 |
}
|
28 |
}
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步骤3：
设计弹幕管理器，管理每一个弹幕实例的发射。
01 |
public class BarrageMgr
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02 |
{
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03 |
//请求子弹
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04 |
public bool AskForBullets (int count, List< Bullet> bullets, Actor owner)
|
05 |
{
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06 |
if (ReloadBullet.Count == 0)
|
07 |
{
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08 |
return false;
|
09 |
}
|
10 |
11 |
if (count >= ReloadBullet.Count)
|
12 |
{
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13 |
count = ReloadBullet.Count;
|
14 |
}
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15 |
16 |
for (int i = 0; i < count; i++)
|
17 |
{
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18 |
ReloadBullet[i].DeactiveObj();
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19 |
Vector2 pos = new Vector2(owner.WorldPosition.X,owner.WorldPosition.Y);
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20 |
21 |
ReloadBullet[i].setPos(pos);
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22 |
bullets.Add(ReloadBullet[i]);
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23 |
24 |
}
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25 |
ReloadBullet.RemoveRange(0,count);
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26 |
return true;
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27 |
}
|
28 |
//处理轨迹
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29 |
public void DealTrajectory (Barrage barrage,float elapsedTime)
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30 |
{
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31 |
_trajectoryMgr.MoveBarrage(barrage,elapsedTime);
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32 |
}
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33 |
//更新弹幕位置
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34 |
public void Tick(float elapsedTime)
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35 |
{
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36 |
foreach (KeyValuePair< uint,Barrage> pair in _barrageDict)
|
37 |
{
|
38 |
39 |
Barrage barrage = pair.Value;
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40 |
|
41 |
DealTrajectory(barrage,elapsedTime);
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42 |
barrage.DestroyBullet();
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43 |
if (!barrage.IsOwnerActive() && barrage.IsAllBulletsDeactive())
|
44 |
{
|
45 |
barrage.Reload();
|
46 |
}
|
47 |
}
|
48 |
Debug.Dbgout( _barrageDict.Count.ToString() );
|
49 |
}
|
50 |
51 |
}
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步骤4：
设计轨迹管理器，使子弹形成一种有规律性的直线运动。
01 |
public class Trajectory
|
02 |
{ |
03 |
//直线轨迹算法
|
04 |
public static Vector2 GoStraight(Vector2 start_pos, float direction,
|
05 |
float start_speed, float accel_speed, float use_time, outVector2 pos)
|
06 |
{
|
07 |
float angle = direction * (float)Math.PI / 180.0f;
|
08 |
float seconds = (float)use_time;
|
09 |
float move_length = start_speed * seconds + accel_speed * seconds * seconds / 2.0f;
|
10 |
pos.X = move_length * (float)Math.Cos(angle) + start_pos.X;
|
11 |
pos.Y = move_length * (float)Math.Sin(angle) + start_pos.Y;
|
12 |
return pos;
|
13 |
}
|
14 |
|
15 |
//这里的跟踪算法主要适用于匀速圆周运动类型的要跟踪,速率不变,一定的旋转角度
|
16 |
//追踪轨迹算法
|
17 |
public static Vector2 Tracking(Vector2 start_pos, ref float direction, Vector2 dest_pos,
|
18 |
float start_speed, float accel_speed, float track_degree,float use_time)
|
19 |
{
|
20 |
Vector2 newpos = new Vector2(0, 0);
|
21 |
|
22 |
if (direction < 0)
|
23 |
{
|
24 |
direction += 360;
|
25 |
}
|
26 |
else
|
27 |
{
|
28 |
direction = direction % 360;
|
29 |
}
|
30 |
|
31 |
//判断目标与飞行的夹角
|
32 |
float degree =(float) (Math.Atan2(dest_pos.Y - start_pos.Y,
|
33 |
dest_pos.X - start_pos.X) * 180 / Math.PI);
|
34 |
if (degree < 0)
|
35 |
{
|
36 |
degree += 360;
|
37 |
}
|
38 |
|
39 |
//最小目标夹角
|
40 |
float dest_degree = (float)Math.Abs(degree - direction) % 360;
|
41 |
if (dest_degree > 180)
|
42 |
{
|
43 |
dest_degree = 360 - dest_degree;
|
44 |
}
|
45 |
if (dest_degree < 0.000001)
|
46 |
{
|
47 |
GoStraight(start_pos, direction, start_speed, accel_speed, use_time,out newpos);
|
48 |
return newpos;
|
49 |
}
|
50 |
|
51 |
//计算最终旋转的夹角
|
52 |
float use_seconds = use_time / 1000.0f;
|
53 |
float rotate_degree = track_degree * use_seconds;
|
54 |
if (rotate_degree > dest_degree)
|
55 |
{
|
56 |
rotate_degree = dest_degree;
|
57 |
}
|
58 |
double inner_degree = degree - direction;
|
59 |
if (inner_degree > 180)
|
60 |
{
|
61 |
direction -= rotate_degree;
|
62 |
}
|
63 |
else if (inner_degree <= 180 && inner_degree >= 0)
|
64 |
{
|
65 |
direction += rotate_degree;
|
66 |
}
|
67 |
else if (inner_degree < -180)
|
68 |
{
|
69 |
direction += rotate_degree;
|
70 |
}
|
71 |
else if (inner_degree >= -180 && inner_degree <= 0)
|
72 |
{
|
73 |
direction -= rotate_degree;
|
74 |
}
|
75 |
|
76 |
GoStraight(start_pos, direction, start_speed, accel_speed, use_time, out newpos);
|
77 |
return newpos;
|
78 |
}
|
79 |
80 |
} |
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