游戏里面经常有转盘活动, 为了让转盘表现自然一点, 就需要自己模拟阻尼运动, 分为三个过程: 匀加速运动, 匀速运动, 匀减速运动

设定最高速度为MaxSpeed, SpeedUp1(匀加速运动的加速度), SpeedUp2(匀减速运动的加速度), Expect(期望停留的弧度点)

其实模拟只需要把两个加运动的区间模拟出来, 剩下的就是匀速运动的区间.

 

1     public struct DampingMotion 2     { 3         /// 最大速度 4         /// 加速运动1 5         /// 减速运动2 6         /// 期望停留在某个弧度 7         public DampingMotion(double maxSpeed, double speedUp1, double speedUp2, double expected) 8         { 9             this.maxSpeed = maxSpeed;10             this.speedUp1 = speedUp1;11             this.speedUp2 = speedUp2;12             this.expected = expected;13 14             time1 = maxSpeed / speedUp1;15             time3 = maxSpeed / speedUp2;16             distance1 = speedUp1 * Math.Pow(time1, 2) / 2;17             distance3 = speedUp2 * Math.Pow(time3, 2) / 2;18             distance2 = expected - (distance1 + distance3) % (Math.PI * 2) + Math.PI * 4;19             time2 = distance2 / maxSpeed;20         }21 22         //单位是秒23         public double GetRotate(double time)24         {25             if (time >= 0 && time < time1)26             {27                 return Math.Pow(time, 2) / 2 * speedUp1;28             }29             if (time >= time1 && time < time1 + time2)30             {31                 return distance1 + (time - time1) * maxSpeed;32             }33             if (time >= time1 + time2 && time < time1 + time2 + time3)34             {35                 var f = time - (time1 + time2);36                 return distance1 + distance2 + (37                     speedUp2 * Math.Pow(time3, 2) / 2 - 38                     speedUp2 * Math.Pow((time3 - f), 2) / 2 39                     );40             }41             return distance1 + distance2 + distance3;42         }43 44         public double maxSpeed;45         public double speedUp1;46         public double speedUp2;47         public double expected;48 49         public double time1; //第一段匀加速的时间50         public double time2; //第二段匀速运动时间51         public double time3; //第三段匀减速运动时间52         private double distance1;53         private double distance2;54         private double distance3;55     }

 

构造好之后, 只需要调用GetRotate函数, 就可以获取某一个时间转盘停留的弧度

这样一个50行不到的代码, 实际上可以当做一个面试题目