粒子系统

学习了3D游戏的粒子系统，参考了I-remember上的例子光环，决定自己做一个。开始动手之前，需要细心观察并发现，光环分两层，一层顺时针旋转另外一层逆时针旋转，且中间部分粒子较多；粒子在旋转的同时会在光环之间游离。

基础准备

新建空对象ParticleCircle，再建两个子对象Clockwise和Anticlockwise，为其添加Particle System组件，新建ParticleCircle脚本并挂载在子对象上：

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using UnityEngine; using System.Collections; public class CirclePosition { public float radius = 0f, angle = 0f, time = 0f; public (float radius, float angle, float time) { this.radius = radius; this.angle = angle; this.time = time; } } public class ParticleCircle : MonoBehaviour { private ParticleSystem particleSys; // 粒子系统 private ParticleSystem.Particle[] particleArr; private CirclePosition[] circle; // 极坐标数组 public int count = 10000; // 粒子数量 public float size = 3f; // 粒子大小 public float minRadius = 4.0f; // 最小半径 public float maxRadius = 8.0f; // 最大半径 public bool clockwise = true; // 顺时针|逆时针 public float speed = 2f; // 速度 public float pingPong = 0.02f; // 游离范围 private int tier = 10; // 速度差分层数 public Gradient colorGradient; // 颜色控制 void RandomlySpread() // 随机布置粒子位置 { for (int i = 0; i < count; ++i) { float midRadius = (maxRadius + minRadius)/2; float minRate = Random.Range(1.0f, midRadius/minRadius); float maxRate = Random.Range(midRadius/maxRadius, 1.0f); float radius = Random.Range(minRadius * minRate, maxRadius * maxRate); float angle = Random.Range(0.0f, 360.0f); // 随机每个粒子的角度 float theta = angle/180 * Mathf.PI; float time = Random.Range(0.0f, 360.0f); // 随机每个粒子的游离起始时间 circle[i] = new CirclePosition(radius, angle, time); particleArr[i].position = new Vector3(circle[i].radius * Mathf.Cos(theta), 0f, circle[i].radius * Mathf.Sin(theta)); } particleSys.SetParticles(particleArr, particleArr.Length); } void Start () { particleArr = new ParticleSystem.Particle[count]; // 初始化粒子数组 circle = new CirclePosition[count]; particleSys = this.GetComponent<ParticleSystem>(); // 初始化粒子系统 particleSys.startSpeed = 0; particleSys.startSize = size; particleSys.loop = false; particleSys.maxParticles = count; // 设置最大粒子量 particleSys.Emit(count); // 发射粒子 particleSys.GetParticles(particleArr); RandomlySpread(); // 初始化各粒子位置 }

旋转粒子

在Update函数里逐渐改变粒子的角度使粒子旋转，其中tier使粒子角度改变量不一致，这样粒子旋转就不会看起来像是图片在旋转：

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void Update () { // 通过改变角度使粒子旋转 for (int i = 0; i < count; i++) { if (clockwise) circle[i].angle -= (i%tier + 1)*(speed/circle[i].radius/tier); else circle[i].angle += (i%tier + 1)*(speed/circle[i].radius/tier); circle[i].angle = (360.0f + circle[i].angle)%360.0f; // 保证angle在0~360度 float theta = circle[i].angle/180 * Mathf.PI; particleArr[i].position = new Vector3(circle[i].radius * Mathf.Cos(theta), 0f, circle[i].radius * Mathf.Sin(theta)); } particleSys.SetParticles(particleArr, particleArr.Length); }

游离粒子

Unity的Mathf的PingPong函数使得值在范围内来回变动，使用它让粒子半径来回变动。以下添加到Update函数中：

1 2	circle[i].time += Time.deltaTime; circle[i].radius += Mathf.PingPong(circle[i].time / minRadius / maxRadius, pingPong) - pingPong / 2.0f;

添加透明度

仔细观察i-remember会发现不同地方亮度不同，也可以说是透明度不同，使用Gradient类可以解决这个问题。一下添加到start函数中：

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GradientAlphaKey[] alphaKeys = new GradientAlphaKey[5]; // 初始化梯度颜色控制器 alphaKeys[0].time = 0.0f; alphaKeys[0].alpha = 1.0f; alphaKeys[1].time = 0.4f; alphaKeys[1].alpha = 0.4f; alphaKeys[2].time = 0.6f; alphaKeys[2].alpha = 1.0f; alphaKeys[3].time = 0.9f; alphaKeys[3].alpha = 0.4f; alphaKeys[4].time = 1.0f; alphaKeys[4].alpha = 0.9f; GradientColorKey[] colorKeys = new GradientColorKey[2]; colorKeys[0].time = 0.0f; colorKeys[0].color = Color.white; colorKeys[1].time = 1.0f; colorKeys[1].color = Color.white; 大专栏  粒子系统 class="line">colorGradient.SetKeys(colorKeys, alphaKeys);

然后在Update中根据粒子的角度改变粒子的透明度:

1	particleArr[i].color = colorGradient.Evaluate(circle[i].angle / 360.0f);

修改参数

修改主摄像机到合适位置：

另外一层是逆时针旋转的，因此把clockwise的勾去掉，同时修改参数直到效果满意：

完整代码

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using UnityEngine; using System.Collections; public class CirclePosition { public float radius = 0f, angle = 0f, time = 0f; public (float radius, float angle, float time) { this.radius = radius; this.angle = angle; this.time = time; } } public class ParticleCircle : MonoBehaviour { private ParticleSystem particleSys; // 粒子系统 private ParticleSystem.Particle[] particleArr; private CirclePosition[] circle; // 极坐标数组 public int count = 10000; // 粒子数量 public float size = 3f; // 粒子大小 public float minRadius = 4.0f; // 最小半径 public float maxRadius = 8.0f; // 最大半径 public bool clockwise = true; // 顺时针|逆时针 public float speed = 2f; // 速度 public float pingPong = 0.02f; // 游离范围 private int tier = 10; // 速度差分层数 public Gradient colorGradient; // 颜色控制 void RandomlySpread() // 随机布置粒子位置 { for (int i = 0; i < count; ++i) { float midRadius = (maxRadius + minRadius)/2; float minRate = Random.Range(1.0f, midRadius/minRadius); float maxRate = Random.Range(midRadius/maxRadius, 1.0f); float radius = Random.Range(minRadius * minRate, maxRadius * maxRate); float angle = Random.Range(0.0f, 360.0f); // 随机每个粒子的角度 float theta = angle/180 * Mathf.PI; float time = Random.Range(0.0f, 360.0f); // 随机每个粒子的游离起始时间 circle[i] = new CirclePosition(radius, angle, time); particleArr[i].position = new Vector3(circle[i].radius * Mathf.Cos(theta), 0f, circle[i].radius * Mathf.Sin(theta)); } particleSys.SetParticles(particleArr, particleArr.Length); } void Start () { particleArr = new ParticleSystem.Particle[count]; // 初始化粒子数组 circle = new CirclePosition[count]; particleSys = this.GetComponent<ParticleSystem>(); // 初始化粒子系统 particleSys.startSpeed = 0; particleSys.startSize = size; particleSys.loop = false; particleSys.maxParticles = count; // 设置最大粒子量 particleSys.Emit(count); // 发射粒子 particleSys.GetParticles(particleArr); RandomlySpread(); // 初始化各粒子位置 GradientAlphaKey[] alphaKeys = new GradientAlphaKey[5]; // 初始化梯度颜色控制器 alphaKeys[0].time = 0.0f; alphaKeys[0].alpha = 1.0f; alphaKeys[1].time = 0.4f; alphaKeys[1].alpha = 0.4f; alphaKeys[2].time = 0.6f; alphaKeys[2].alpha = 1.0f; alphaKeys[3].time = 0.9f; alphaKeys[3].alpha = 0.4f; alphaKeys[4].time = 1.0f; alphaKeys[4].alpha = 0.9f; GradientColorKey[] colorKeys = new GradientColorKey[2]; colorKeys[0].time = 0.0f; colorKeys[0].color = Color.white; colorKeys[1].time = 1.0f; colorKeys[1].color = Color.white; colorGradient.SetKeys(colorKeys, alphaKeys); } void Update () { // 通过改变角度使粒子旋转 for (int i = 0; i < count; i++) { if (clockwise) circle[i].angle -= (i%tier + 1)*(speed/circle[i].radius/tier); else circle[i].angle += (i%tier + 1)*(speed/circle[i].radius/tier); circle[i].angle = (360.0f + circle[i].angle)%360.0f; // 保证angle在0~360度 float theta = circle[i].angle/180 * Mathf.PI; particleArr[i].position = new Vector3(circle[i].radius * Mathf.Cos(theta), 0f, circle[i].radius * Mathf.Sin(theta)); circle[i].time += Time.deltaTime; // 使粒子半径波动 circle[i].radius += Mathf.PingPong(circle[i].time/minRadius/maxRadius, pingPong) - pingPong/2.0f; particleArr[i].color = colorGradient.Evaluate(circle[i].angle/360.0f); // 根据角度改变透明度 } particleSys.SetParticles(particleArr, particleArr.Length); } }

ParticleSea

以下是另外一个利用粒子系统写的粒子海洋，有兴趣可以做做：