焰火粒子系统
此效果类似放烟花的效果，粒子从一个以不同速度点向上喷出，达到最高点然后向下散落，和上一个小球的示例类似，两个线程进行控制，一个控制改变添加粒子和改变他们的轨迹，另一个线程不停地绘制屏幕元素。两者结合完成此效果。代码如下：
MainActivity：
package com.home.particle;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
import android.app.Activity;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// 设置不显示标题
requestWindowFeature(Window.FEATURE_NO_TITLE);
// 设置全屏模式
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
ParticleView pv = new ParticleView(this);
setContentView(pv);
}
}
ParticleView：
package com.home.particle;
import java.util.ArrayList;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
/**
* 试图类
*
* @author Administrator
*
*/
public class ParticleView extends SurfaceView implements SurfaceHolder.Callback {
public static final int DIE_OUT_LINE = 500;// 屏幕下边缘界限
DrawThread dt;
ParticleSet ps;
ParticleThread pt;
String fps = "FPS:N/A";// 帧速率
public ParticleView(Context context) {
super(context);
this.getHolder().addCallback(this);
dt = new DrawThread(this, getHolder());
ps = new ParticleSet();
pt = new ParticleThread(this);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// 启动线程
if (!dt.isAlive()) {
dt.start();
}
if (!pt.isAlive()) {
pt.start();
}
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
dt.flag = false;
dt = null;
pt.flag = false;
pt = null;
}
public void doDraw(Canvas canvas) {
canvas.drawColor(Color.BLACK);// 清除屏幕
ArrayList<Particle> particleSet = ps.particleSet;
Paint paint = new Paint();
for (int i = 0; i < particleSet.size(); i++) {
Particle p = particleSet.get(i);
paint.setColor(p.color);
int tempX = p.x;
int tempY = p.y;
int tempRadius = p.r;
RectF oval = new RectF(tempX, tempY, tempX + 2 * tempRadius, tempY
+ 2 * tempRadius);
canvas.drawOval(oval, paint);// 绘制椭圆粒子
}
paint.setColor(Color.WHITE);
paint.setTextSize(18);
paint.setAntiAlias(true);
canvas.drawText(fps, 15, 15, paint);// 绘制帧速率
}
}
DrawThread：
package com.home.particle;
import android.graphics.Canvas;
import android.view.SurfaceHolder;
/**
* 绘制屏幕的线程
*
* @author Administrator
*
*/
public class DrawThread extends Thread {
ParticleView pv;
SurfaceHolder holder;
boolean flag;
int sleepSpan = 15;
long start = System.nanoTime();
int count = 0;// 记录帧数，该变量用于计算帧速率
public DrawThread(ParticleView pv, SurfaceHolder holder) {
this.pv = pv;
this.holder = holder;
this.flag = true;
}
@Override
public void run() {
Canvas canvas = null;
while (flag) {
try {
canvas = holder.lockCanvas(null);
synchronized (holder) {
pv.doDraw(canvas);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (canvas != null) {
holder.unlockCanvasAndPost(canvas);
}
}
this.count++;
if (count == 20) {
count = 0;
long tempStamp = System.nanoTime();
long span = tempStamp - start;
start = tempStamp;
// 计算帧速率
double fps = Math.round(100000000000.0 / span * 20) / 100.0;
pv.fps = "FPS:" + fps;
}
try {
Thread.sleep(sleepSpan);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
ParticleThread：
package com.home.particle;
import java.util.ArrayList;
/**
* 添加粒子和改变轨迹的线程
*
* @author Administrator
*
*/
public class ParticleThread extends Thread {
boolean flag;// 线程执行的标志
ParticleView father;// ParticleView对象的引用
int sleepSpan = 80;// 线程休眠时间
double time = 0;// 物理引擎的时间轴
double span = 0.15;// 每次计算粒子位移的时间间隔
public ParticleThread(ParticleView father) {
this.father = father;
this.flag = true;
}
@Override
public void run() {
while (flag) {
father.ps.add(5, time);// 每次添加5个粒子
// 获取粒子集合
ArrayList<Particle> tempSet = father.ps.particleSet;
int count = tempSet.size();
// 遍历粒子集合修改其轨迹
for (int i = 0; i < count; i++) {
Particle particle = tempSet.get(i);
// 计算从程序开始到现在经过的时间
double timeSpan = time - particle.startTime;
// 计算x坐标
int tempx = (int) (particle.startX + particle.horizontal_v
* timeSpan);
// 计算y坐标
int tempy = (int) (particle.startY + 4.9 * timeSpan * timeSpan + particle.vertical_v
* timeSpan);
if (tempy > ParticleView.DIE_OUT_LINE) {// 如果粒子超过屏幕下边缘
tempSet.remove(particle);// 移除
count = tempSet.size();// 重设置粒子个数
}
// 修改粒子坐标
particle.x = tempx;
particle.y = tempy;
}
time += span;// 将时间延长
try {
Thread.sleep(sleepSpan);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
Particle：
package com.home.particle;
/**
* 粒子实体类
*
* @author Administrator
*
*/
public class Particle {
int color;// 颜色
int r;// 半径
double vertical_v;// 垂直速度
double horizontal_v;// 水平速度
int startX;// 初始x坐标
int startY;// 初始y坐标
int x;// 实时x坐标
int y;// 实时y坐标
double startTime;// 起始时间
public Particle(int color, int r, double vertical_v, double horizontal_v,
int x, int y, double startTime) {
this.color = color;
this.r = r;
this.vertical_v = vertical_v;
this.horizontal_v = horizontal_v;
this.startX = x;
this.startY = y;
this.x = x;
this.y = y;
this.startTime = startTime;
}
}
ParticleSet：
package com.home.particle;
import java.util.ArrayList;
import android.graphics.Color;
/**
* 负责管理和添加粒子对象
*
* @author Administrator
*
*/
public class ParticleSet {
ArrayList<Particle> particleSet;// 存放粒子对象的集合
public ParticleSet() {
particleSet = new ArrayList<Particle>();
}
/**
* 向粒子集合添加指定个数的粒子对象
*
* @param count
* @param startTime
*/
public void add(int count, double startTime) {
for (int i = 0; i < count; i++) {
int tempColor = this.getColor(i);
int tempR = 1;
// 随机产生粒子竖直方向的速度
double tempv_v = -30 + 10 * (Math.random());
// 随机产生粒子水平方向的速度
double tempv_h = 10 - 20 * (Math.random());
int tempX = 260;
// 随机产生粒子Y坐标，90~100之间
int tempY = (int) (100 - 10 * (Math.random()));
// 创建粒子对象
Particle particle = new Particle(tempColor, tempR, tempv_v,
tempv_h, tempX, tempY, startTime);
particleSet.add(particle);// 加入集合
}
}
/**
* 根据索引得到不同的颜色
*
* @param i
* @return
*/
public int getColor(int i) {
int color = Color.RED;
switch (i % 4) {
case 0:
color = Color.RED;
break;
case 1:
color = Color.GREEN;
break;
case 2:
color = Color.YELLOW;
break;
case 3:
color = Color.GRAY;
break;
}
return color;
}
}
附上一张图片：
