弹跳球回到android
Nik*_*tel 3 java android accelerator
我已经使用SensorManager的加速器示例,其中画布(球)根据设备加速器旋转更新其位置.这是图像:
如图所示,有一个球和一条线.球的位置经常更新,而线的位置是静态的.
我想让球在接触线时反弹回来.我从3天开始尝试过,但是不明白我是怎么做到的.
这是我的代码:
public class ballsensor extends Activity implements SensorEventListener {
// sensor-related
private SensorManager mSensorManager;
private Sensor mAccelerometer;
// animated view
private ShapeView mShapeView;
// screen size
private int mWidthScreen;
private int mHeightScreen;
// motion parameters
private final float FACTOR_FRICTION = 0.5f; // imaginary friction on the
// screen
private final float GRAVITY = 9.8f; // acceleration of gravity
private float mAx; // acceleration along x axis
private float mAy; // acceleration along y axis
private final float mDeltaT = 0.5f; // imaginary time interval between each
// acceleration updates
// timer
private Timer mTimer;
private Handler mHandler;
private boolean isTimerStarted = false;
private long mStart;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// set the screen always portait
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
// initializing sensors
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
mAccelerometer = mSensorManager
.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
// obtain screen width and height
Display display = ((WindowManager) this
.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
mWidthScreen = display.getWidth();
mHeightScreen = display.getHeight() - 35;
// initializing the view that renders the ball
mShapeView = new ShapeView(this);
mShapeView.setOvalCenter((int) (mWidthScreen * 0.6),
(int) (mHeightScreen * 0.6));
setContentView(mShapeView);
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
@Override
public void onSensorChanged(SensorEvent event) {
// obtain the three accelerations from sensors
mAx = event.values[0];
mAy = event.values[1];
float mAz = event.values[2];
// taking into account the frictions
mAx = Math.signum(mAx) * Math.abs(mAx)
* (1 - FACTOR_FRICTION * Math.abs(mAz) / GRAVITY);
mAy = Math.signum(mAy) * Math.abs(mAy)
* (1 - FACTOR_FRICTION * Math.abs(mAz) / GRAVITY);
}
@Override
protected void onResume() {
super.onResume();
// start sensor sensing
mSensorManager.registerListener(this, mAccelerometer,
SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
protected void onPause() {
super.onPause();
// stop senser sensing
mSensorManager.unregisterListener(this);
}
// the view that renders the ball
private class ShapeView extends SurfaceView implements
SurfaceHolder.Callback {
private final int RADIUS = 30;
private final float FACTOR_BOUNCEBACK = 0.50f;
private int mXCenter;
private int mYCenter;
private RectF mRectF;
private final Paint mPaint;
private ShapeThread mThread;
private float mVx;
private float mVy;
public ShapeView(Context context) {
super(context);
getHolder().addCallback(this);
mThread = new ShapeThread(getHolder(), this);
setFocusable(true);
mPaint = new Paint();
mPaint.setColor(0xFFFFFFFF);
mPaint.setAlpha(192);
mPaint.setStyle(Paint.Style.FILL_AND_STROKE);
mPaint.setAntiAlias(true);
mRectF = new RectF();
}
// set the position of the ball
public boolean setOvalCenter(int x, int y) {
mXCenter = x;
mYCenter = y;
return true;
}
// calculate and update the ball's position
public boolean updateOvalCenter() {
mVx -= mAx * mDeltaT;
mVy += mAy * mDeltaT;
System.out.println("mVx is ::" + mVx);
System.out.println("mVy is ::" + mVy);
mXCenter += (int) (mDeltaT * (mVx + 0.6 * mAx * mDeltaT));
mYCenter += (int) (mDeltaT * (mVy + 0.6 * mAy * mDeltaT));
if (mXCenter < RADIUS) {
mXCenter = RADIUS;
mVx = -mVx * FACTOR_BOUNCEBACK;
}
if (mYCenter < RADIUS) {
mYCenter = RADIUS;
mVy = -mVy * FACTOR_BOUNCEBACK;
}
if (mXCenter > mWidthScreen - RADIUS) {
mXCenter = mWidthScreen - RADIUS;
mVx = -mVx * FACTOR_BOUNCEBACK;
}
if (mYCenter > mHeightScreen - 2 * RADIUS) {
mYCenter = mHeightScreen - 2 * RADIUS;
mVy = -mVy * FACTOR_BOUNCEBACK;
}
return true;
}
// update the canvas.
@Override
protected void onDraw(Canvas canvas) {
if (mRectF != null) {
mRectF.set(mXCenter - RADIUS, mYCenter - RADIUS, mXCenter
+ RADIUS, mYCenter + RADIUS);
canvas.drawColor(0XFF000000);
// canvas.drawOval(mRectF, mPaint);
Bitmap kangoo = BitmapFactory.decodeResource(getResources(),
R.drawable.stripe1);
Bitmap ball = BitmapFactory.decodeResource(getResources(),
R.drawable.blackwhiteball);
canvas.drawBitmap(ball, mXCenter - RADIUS, mYCenter - RADIUS,
mPaint);
canvas.drawBitmap(kangoo, 130, 10, null);
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
mThread.setRunning(true);
mThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
mThread.setRunning(false);
while (retry) {
try {
mThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
}
class ShapeThread extends Thread {
private SurfaceHolder mSurfaceHolder;
private ShapeView mShapeView;
private boolean mRun = false;
public ShapeThread(SurfaceHolder surfaceHolder, ShapeView shapeView) {
mSurfaceHolder = surfaceHolder;
mShapeView = shapeView;
}
public void setRunning(boolean run) {
mRun = run;
}
public SurfaceHolder getSurfaceHolder() {
return mSurfaceHolder;
}
@Override
public void run() {
Canvas c;
while (mRun) {
mShapeView.updateOvalCenter();
c = null;
try {
c = mSurfaceHolder.lockCanvas(null);
synchronized (mSurfaceHolder) {
mShapeView.onDraw(c);
}
} finally {
if (c != null) {
mSurfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
}
}
Ric*_*lli 13
而不是尝试修复代码,而是通过开发具有两个组件的软件架构在设计层面工作:物理模型和显示.关键是将问题的物理特性与显示分开.与显示器分开进行时,物理建模变得更加容易.同样,显示也变得更容易.有两个独立的包 - 一个用于物理,一个用于显示.
从一个更简单的问题版本开始,物理世界只有一个点和一条线.模拟从线上反射的点.你有一些代码可以做到这一点.只需将其从当前代码中删除即可.确保物理学能够达到您的预期,而不必担心显示器.
设计一个球类.球具有速度和位置属性.它有一个移动方法,可以根据一次点击的速度更新位置.移动方法检查它是否与墙相互作用(碰撞)并根据您希望世界拥有的物理变化速度.碰撞检测是通过询问墙壁是否完成来完成的.物理学可以是入射角等于反射角,或者你可以在球上有一个旋转属性来改变球的反弹方式.关键是所有的物理建模都是与显示器分开完成的.同样,您可以为墙创建一个类.最初墙是固定的,但你可以添加移动.好的一点是,如果你设计了球类正确地改变墙壁使其移动不会影响球类的设计.此外,这些物理变化都不会影响显示的完成方式.
制作一个简单地将物理翻译成屏幕上的演示文稿的显示.
从那里,您可以增加模型的复杂性.将点设为圆.重做物理学以使其适应这种新的复杂性.显示器不会有太大变化,但要将它们分开.
我有我的CS1类做同样问题的版本.两年前,我让他们做了一场乒乓球比赛.去年是蜈蚣的一个版本.即将到来的学期他们将突破作为一个项目.当他们将物理模型与显示器分开建模时,他们就能使用它.当他们不这样做时,通常是一团糟.