烟花爆炸动效

    越来越多的地方都会用到烟花效果了，而且很多游戏都会有类似通关之后的爆炸特效，今天来分享一下烟花爆炸的动效。升空的动画就不用写了，主要就写个view的位移，重点就是四散开来的爆炸。下面见见效果：

下面就来看如何处理的吧，将烟花爆炸的火花转变为bitmap,然后根据这个火花的个数，创建出多个bitmap,给每一个bitmap一个随机的角度，为后面的四散做准备：

 private void init() {
        Random random = new Random(System.currentTimeMillis());
    // color = colors[random.nextInt(colors.length)];
    // 给每个火花设定一个随机的方向 0-360
        elements.clear();
        Log.d("zxc118", "Firework init mode = " + mode + " count = " + count);
        if (mode == 0) {
            for (int i = 0; i < count; i++) {
                color = bitmapColor[random.nextInt(bitmapColor.length)];
                InputStream is = context.getResources().openRawResource(color);
                Bitmap mBitmap = BitmapFactory.decodeStream(is);
                elements.add(new Element(color, Math.toRadians(random
                        .nextInt(360)), random.nextFloat() * launchSpeed,
                        mBitmap));
            }
        } else {
            float bitmapScale = 2;
            if (srceenWidth > 0) {
                bitmapScale = srceenWidth / screenWidthMeasure * bitmapScale;
            }
            for (int i = 0; i < count; i++) {
                InputStream is = context.getResources().openRawResource(color);//小星星图片资源id
                Bitmap mBitmap = BitmapFactory.decodeStream(is);
              /*  Bitmap shapeBitmap = Utils.drawShapeBitmap(mBitmap,
                        (int) (srceenWidth / screenWidthMeasure * starSize),
                        "star");*/

                Bitmap shapeBitmap = imageScale(mBitmap, 35, 35);


                elements.add(new Element(color, Math.toRadians(random
                        .nextInt(360)), random.nextFloat() * launchSpeed,
                        shapeBitmap));
            }


        }
        mPaint = new Paint();
        mPaint.setColor(Color.WHITE);
        timeCount = 1;
        animatorValue = timeCount;
    }

剩下就是爆炸，这个爆炸就是给火花一个随机的位置进行移动，然后通过不停的绘画，然后在屏幕上产生效果，当然这个中间会有不断的更新火花的位置，为这个火花下一次位置做准备。

 * 开始烟花爆炸动画
     */
    public void fire() {
        animator = ValueAnimator.ofFloat(1, 0);
        animator.setDuration(duration);
//从头开始动画
        animator.setRepeatMode(ValueAnimator.RESTART);
        animator.setInterpolator(new AccelerateInterpolator());
        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator valueAnimator) {
                animatorValue = (Float) valueAnimator.getAnimatedValue();
                Log.d("zxc55", "onAnimationUpdate animatorValue = " + animatorValue);
// 计算每个火花的位置
                isStart = true;
                for (Element element : elements) {
                    element.x = (float) (element.x
                            + Math.cos(element.direction) * element.speed
                            * animatorValue + windSpeed * windDirection);
                    element.y = (float) (element.y
                            - Math.sin(element.direction) * element.speed
                            * animatorValue + gravity * (1 - animatorValue));
                }
            }
        });
        animator.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                Log.d("zxc118", "onAnimationEnd clear animator");
                listener.onAnimationEnd(Firework.this);
                needRemove = true;
            }
        });
        animator.start();
//        if (mode == 0 && sounds != null) {
//            sounds.playSound(9, 0);
//        }

    }

再来看看将这个火花绘制到画布上，和更新位置的代码吧。

 public void draw(Canvas canvas) {
        mPaint.setAlpha((int) (225 * animatorValue));
        /*
         * 有些情况小星星动画不能停止，强制结束
         */
        n++;
        if (n > maxTime) {
            listener.onAnimationEnd(Firework.this);
        }
        Random random = new Random();
        for (Element element : elements) {
            float left = location.x + element.x/3;
            float top = location.y + element.y/3;
//            left=left-left*200/rangeSize;
//            top=top-top*200/rangeSize;
            mPaint.setAlpha(random.nextInt(225));
            canvas.drawBitmap(element.bitmap, left,
                    top, mPaint);
        }
        /*
         * 更新烟花位置
         */
        if (n > 2 && !isStart) {
            updateLocation();
        }
    }


    public void updateLocation() {
        animatorValue -= dif;
        if (animatorValue < 0) {
            listener.onAnimationEnd(Firework.this);
        }
        for (Element element : elements) {
            element.x = (float) (element.x
                    + Math.cos(element.direction) * element.speed
                    * animatorValue + windSpeed * windDirection);
            element.y = (float) (element.y
                    - Math.sin(element.direction) * element.speed
                    * animatorValue + gravity * (1 - animatorValue));


        }
    }

大概也就这些，下面给出demo地址：https://download.csdn.net/download/greatdaocaoren/12538519