【3D游戏】粒子光环

【3D游戏】粒子光环

参考 这类网站，使用粒子流编程控制制作一些效果， 如“粒子光环”

粒子分布

因为要实现的效果是粒子光环，因此可以用服从正态分布的光环半径来模拟粒子的分布。正态分布的数组可以通过Box-Muller算法得到。Box-Muller算法的效果是将均匀分布的随机数转为正态分布。

class Ndistribution {System.Random rand = new System.Random();public double getNormalDistribution(double mean, double stdDev) {double u1 = 1.0 - rand.NextDouble(); //uniform(0,1] random doublesdouble u2 = 1.0 - rand.NextDouble();double randStdNormal = Math.Sqrt(-2.0 * Math.Log(u1)) *Math.Sin(2.0 * Math.PI * u2); //random normal(0,1)double randNormal = mean + stdDev * randStdNormal; //random normal(mean,stdDev^2)return randNormal;}

光环初始化

每个粒子初始化时都通过Box-Muller算法得到的正态分布设定好收缩前后的粒子半径，同时设定好0到360度之间的随机角度，就初始化好了粒子光环。

		for (int i = 0; i < particleNum; i++) {float r = (NormalDistribution((minRadius+maxRadius)*0.5f, 1);float angle = UnityEngine.Random.Range(0.0f, 360.0f);particleAngle[i] = angle;particleR[i] = r;before[i] = r;after[i] = 0.7f * r;if (after[i] < minRadius * 1.1f) {float midRadius = minRadius * 1.05f;after[i] = UnityEngine.Random.Range(UnityEngine.Random.Range(minRadius, midRadius), (minRadius * 1.1f));}}

光环旋转

利用Update()函数实现粒子旋转的效果，使下标按奇偶性不同按相反方向旋转，并且根据速度等级不通实现不同速度旋转。

 			if (i % 2 == 0) {particleAngle[i] += (i % speedLevel + 1) * particleSpeed;  } else {particleAngle[i] -= (i % speedLevel + 1) * particleSpeed;  }  particleAngle[i] = particleAngle[i] % 360;float rad = particleAngle[i] / 180 * Mathf.PI;  particles[i].position = new Vector3(particleR[i] * Mathf.Cos(rad), particleR[i] * Mathf.Sin(rad), 0f); 

光环收缩

为光环中设置一个区域，鼠标悬停在此区域即收缩，离开则还原。

                if(particleR[i] > after[i]) {particleR[i] -= shrinkSpeed * (particleR[i] / after[i]) * Time.deltaTime;}} else {if (particleR[i] < before[i]) {particleR[i] += shrinkSpeed * (before[i] / particleR[i]) * Time.deltaTime;} else if (particleR[i] > before[i]) {particleR[i] = before[i];}}