as 关于BOX2D刚体有时无法休眠的原因及处理方法

这段是b2Island.as的方法..

 

//if (minSleepTime >= b2Settings.b2_timeToSleep)
这个是BOX2D原来的判定...
b2Settings.b2_timeToSleep指向的值是0.5
minSleepTime 是根据时间步的值来增加的..
如果只有一个刚体..时间步是1/24的话..即使要休眠也达不到0.5的要求..

b2Settings.b2_timeToSleep的意思是最小休眠时间....

不过0.5一样还有问题...

于是我就把这段函数改了下..

增加了两句:
var needSleep:Boolean = true;
needSleep = contactsOkay && needSleep;

并把判定改为:
minSleepTime >= step.dt && needSleep

这样位置修正也没问题..也可以休眠了

 

1  Report(contactSolver.m_constraints);
 2
 3                
 4
 5  if (allowSleep){
 6
 7                        
 8
 9          var minSleepTime:Number = Number.MAX_VALUE;
10
11                        
12
13          var linTolSqr:Number = b2Settings.b2_linearSleepTolerance * b2Settings.b2_linearSleepTolerance;
14
15          var angTolSqr:Number = b2Settings.b2_angularSleepTolerance * b2Settings.b2_angularSleepTolerance;
16
17                        
18
19           for (i = 0; i < m_bodyCount; ++i)
20
21          {
22
23                 b = m_bodies[i];
24
25                 if (b.m_invMass == 0.0)
26
27                {
28
29                        continue;
30
31                }
32
33                                
34
35               if ((b.m_flags & b2Body.e_allowSleepFlag) == 0 ||
36
37                                        b.m_angularVelocity * b.m_angularVelocity > angTolSqr ||
38
39                                        b2Math.b2Dot(b.m_linearVelocity, b.m_linearVelocity) > linTolSqr)
40
41           {
42
43                    b.m_sleepTime = 0.0;
44
45                    minSleepTime = 0.0;
46
47            }
48
49           else
50
51          {
52
53                 b.m_sleepTime += step.dt;
54
55                 minSleepTime = b2Math.b2Min(minSleepTime, b.m_sleepTime);
56
57           }
58
59     }
60
61
62     if (minSleepTime >= step.dt && needSleep)
63
64    {
65
66          for (i = 0; i < m_bodyCount; ++i)
67
68          {
69
70                 b = m_bodies[i];
71
72                 if ( b.m_sleepTime >= step.dt)
73
74                {
75
76                      b.m_flags |= b2Body.e_sleepFlag;
77
78                      b.m_linearVelocity.SetZero();
79
80                      b.m_angularVelocity = 0.0;
81
82                 }
83
84        }
85
86 }

 上面的代码还是有点问题,改了后.会无缘无故的漂浮..

但是可以增加是否有碰撞..就可以解决无缘无故的漂浮..

..我给BODY类加了一个碰撞属性..

碰撞时改为TRUE..

然后睡眠时再判定是不是有碰撞..

具体代码我就不贴了..