android实现简单的火焰效果

先上图

xz1.gif xz2.gif

其实比较简单，其实就是canvas绘制图形，步骤就不赘述了，直接上代码

public class Particle {
    //火焰粒子坐标
    private float x;
    private float y;
    public float xv = 1;//x轴加速度
    public float yv = 1;//y轴加速度
    public int alpha;

    public Particle(float x, float y) {
        this.x = x;
        this.y = y;
    }

    public float getX() {
        return x;
    }

    public void setX(float x) {
        this.x = x;
    }

    public float getY() {
        return y;
    }

    public void setY(float y) {
        this.y = y;
        //500-200为火焰的y轴左边范围，所以根据这个计算透明度
        alpha = (int) ((y-200)*255/300);
    }
}

粒子系统类

public class ParticleSystem {
    private List<Particle> particles = new ArrayList<>();
    private int border_width = 20;
    private Paint paint = new Paint();
    private Random random;

    public ParticleSystem(int particlesCount) {
        paint.setColor(Color.RED);
        random = new Random();
        for (int i = 0; i < particlesCount; i++) {
            Particle particle = new Particle(100 + 100 * random.nextFloat(), 500);
            particle.xv = 0.5f - 1 * random.nextFloat();
            particles.add(particle);
        }
    }

    public void onDraw(Canvas canvas) {
        for (int i = 0; i < particles.size(); i++) {
            Particle particle = particles.get(i);
            paint.setAlpha(particle.alpha);
            canvas.drawRect(particle.getX(), particle.getY(), particle.getX() + border_width, particle.getY() + border_width, paint);
        }
    }

    /**
     * 粒子集合更新方法
     *
     * @param wind wind是风，0时代表无风，粒子不偏移
     */
    public void update(float wind) {
        for (int i = 0; i < particles.size(); i++) {
            Particle particle = particles.get(i);
            if (particle.xv > 0) {
                //当初始加速度为正，就一直为正
                particle.xv += 0.01f + wind;
            } else {
                //当初始加速度为负，就一直为正
                particle.xv += -0.01f + wind;
            }
            particle.yv = particle.yv + 0.1f;
            particle.setX(particle.getX() + particle.xv);
            particle.setY(particle.getY() - particle.yv);
        }
        List<Particle> list = new ArrayList<>();
        list.addAll(particles);
        for (Particle particle : list) {
            if (particle.getY() < 200) {
                particles.remove(particle);
            }
        }
        for (int i = 0; i < 5; i++) {
            Particle particle = new Particle(100 + 100 * random.nextFloat(), 500);

            particle.xv = 0.5f - 1 * random.nextFloat();
            particles.add(particle);
        }
    }
}

public class MyView extends SurfaceView implements SurfaceHolder.Callback{
    private SurfaceHolder holder;
    private MyThread thread;
    public boolean running = true;
    private ParticleSystem particleSystem;
    private Paint paint;
    public MyView(Context context) {
        super(context);
        init();
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }
    private void init(){
        holder = getHolder();
        holder.addCallback(this);
        thread = new MyThread();
        particleSystem = new ParticleSystem(50);
        paint = new Paint();
        paint.setColor(Color.BLACK);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        running = true;
        thread.start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        running = false;
    }

    class  MyThread extends Thread{
        @Override
        public void run() {
            super.run();
            while(true){
                if(running){
                    drawUI();
                }
            }
        }
    }

    private void drawUI(){
        Canvas canvas = holder.lockCanvas();

        if(canvas==null){
            return;
        }
        canvas.drawRect(0,0,getWidth(),getHeight(),paint);
        particleSystem.onDraw(canvas);
        particleSystem.update(new Random().nextFloat()*0.18f);
        holder.unlockCanvasAndPost(canvas);
    }
}