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[英]Android sqlite - how to calculate the difference between 2 REAL entries in sqlite?
[英]Android Canvas.How to calculate difference between centres in loop?
我是新的android。 試圖實現反彈球。 像這樣
我的BouncingBallView類如下所示:
private ArrayList<Ball> balls;
public BouncingBallView(Context context) {
super(context);
this.balls = new ArrayList<>();
for(int i=0; i<2; i++)
this.balls.add(addBall());
}
public Ball addBall(){
Ball ball;
// Init the ball at a random location (inside the box) and moveAngle
Random rand = new Random();
int radius = 60;
int x = rand.nextInt(500 - radius * 2 - 20) + radius + 10;
int y = rand.nextInt(800- radius * 2 - 20) + radius + 10;
int speed = 10;
int angleInDegree = rand.nextInt(360);
ball = new Ball(x, y, radius, speed, angleInDegree);
return ball;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for(int i=0; i < balls.size(); i++)
balls.get(i).draw(canvas);
for(int i=0; i < balls.size(); i++){
balls.get(i).intersect(canvas);
// Update the ball's state with proper collision response if collided.
balls.get(i).update();
}
for(int i=0; i<balls.size(); i++){
balls.get(i).collide(balls);
}
invalidate();
}
並且Ball類具有方法collide();
public void collide(ArrayList<Ball> balls){
//Log.d("TEst", "LOG");
// Calculate difference between centres
float distX = balls.get(0).getBallX() - balls.get(1).getBallX();
float distY = balls.get(0).getBallY() - balls.get(1).getBallY();
// Get distance with Pythagora
double dist = Math.sqrt((distX * distX) + (distY * distY));
float r = ballRadius + ballRadius;
if ((float) dist <= r) {
Log.d("Collide", "Detected");
this.ballSpeedX = -this.ballSpeedX;
this.ballSpeedY = -this.ballSpeedY++;
}
/*for(int i=0; i < balls.size(); i++) {
for(int j=1; j<balls.size(); j++) {
// Calculate difference between centres
float distX = balls.get(i).getBallX() - balls.get(j).getBallX();
float distY = balls.get(i).getBallY() - balls.get(j).getBallY();
// Get distance with Pythagora
double dist = Math.sqrt((distX * distX) + (distY * distY));
*//*double distance = Math.sqrt(((balls.get(0).getBallX() - balls.get(1).getBallX()) * (balls.get(0).getBallX() - balls.get(1).getBallX())) + ((balls.get(0).getBallY()
- balls.get(1).getBallY()) * (balls.get(0).getBallY() - balls.get(1).getBallY())));*//*
float r = ballRadius + ballRadius;
if ((float) dist <= r) {
Log.d("Collide", "Detected");
this.ballSpeedX = -this.ballSpeedX;
this.ballSpeedY = -this.ballSpeedY++;
}
}
}*/
}
在這里,我使用畢達哥拉斯定理a ^ 2 + b ^ 2 = c ^ 2來計算兩個圓心之間的距離。 如果球數> 2,如何計算。我嘗試循環播放,但效果非常差(凍結球)。
您可以找到完整的代碼github
現在像這個視頻一樣工作我的彈跳球視頻
感謝幫助;)
抱歉,英語太差了。
您可以在每個階段都有一個用於球的計數器,當一個球被銷毀時(如果您將其銷毀),您可以更改計數並可以在collide方法中檢查(計數器)。
但是我沒關系,您不需要檢查這種情況,如果發生碰撞,那么可以,否則該方法什么也不會發生。
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