java - 碰撞相同程式碼，跑出來的值會不一樣
MainActivity.java
B[CURRENT_BALL].Vx = (float) (-(event.getX()-B[CURRENT_BALL].BX)/s);
B[CURRENT_BALL].Vy = (float) (-(event.getY()-B[CURRENT_BALL].BY)/s);
B[CURRENT_BALL].V = (double) (4000);
//位移量X分量
B[i].MX = B[i].Vx*B[i].V*T;
//位移量Y分量
B[i].MY = B[i].Vy*B[i].V*T;
private void BallCollision(){
double T = updateT;
T = T/1000;
for(int i = 0 ; i < B.length ;i++){
if(B[i].V>0){
//hitRect(i);
}
for(int j = i+1 ; j < B.length ;j++){
//碰撞(兩球距離小於等於圓心距)
if(countDistance(B[i],B[j])<=B[i].radius+B[j].radius){
//同一顆球不判斷喔:)
if(i==j)continue;
if (B[i].V==0 && B[j].V==0) continue;
double rc = (double) countDistance(B[i],B[j]);
//修正小球碰撞距離
//獲取碰撞後的速度增量
double ax = (double) (((B[i].MX - B[j].MX)*Math.pow((B[i].BX - B[j].BX) , 2) + (B[i].MY - B[j].MY)*(B[i].BX - B[j].BX) *(B[i].BY - B[j].BY))/Math.pow(rc , 2));
double ay = (double) (((B[i].MY - B[j].MY)*Math.pow((B[i].BY - B[j].BY) , 2) + (B[i].MX - B[j].MX)*(B[i].BX - B[j].BX)*(B[i].BY - B[j].BY))/Math.pow(rc , 2));
//Log.d("Mine","ax: "+ax);
//將速度增量賦給碰撞小球
B[i].MX = (B[i].MX- ax);
B[i].MY = (B[i].MY- ay);
B[j].MX = (B[j].MX+ ax);
B[j].MY = (B[j].MY+ ay);
B[i].V = ((double) (Math.sqrt(Math.pow((B[i].MX),2)+Math.pow((B[i].MY), 2))/T));
B[j].V = ((double) (Math.sqrt(Math.pow((B[j].MX),2)+Math.pow((B[j].MY), 2))/T));
MoveS1 = ((double) Math.sqrt(Math.pow((B[i].MX),2)+Math.pow((B[i].MY), 2)));
MoveS2 = ((double) Math.sqrt(Math.pow((B[j].MX),2)+Math.pow((B[j].MY), 2)));
B[i].Vx = (B[i].MX/MoveS1);
B[i].Vy = (B[i].MY/MoveS1);
B[j].Vx = (B[j].MX/MoveS2);
B[j].Vy = (B[j].MY/MoveS2);
double clength = (((B[i].radius+B[j].radius)-rc)/2);
double cx = (clength * (B[i].BX-B[j].BX)/rc);
double cy = (clength * (B[i].BY-B[j].BY) /rc);
B[i].X = (int) (B[i].X+ cx);
B[i].Y = (int) (B[i].Y+ cy);
B[j].X = (int) (B[j].X- cx);
B[j].Y = (int) (B[j].Y- cy);
B[i].BX = (int) (B[i].BX+ cx);
B[i].BY = (int) (B[i].BY+ cy);
B[j].BX = (int) (B[j].BX- cx);
B[j].BY = (int) (B[j].BY- cy);
if(B[i].V>0){
B[i].V = (double) (B[i].V*0.9);
}if(B[j].V>0){
B[i].V = (double) (B[i].V*0.9);
}
}
}
}
}Ball.java
public class Ball extends View {
int X;
int Y;
double V;//速度
double A = -10f;//加速度
double width;//長
double height;//寬
double radius;//半徑
int BX;//球心X
int BY;//球心Y
double MX;
double MY;
//double M = 5;
int img;//圖片
Bitmap bitmap;
double Vx =0 , Vy =0;//移動方向 單位向量xy分量
Ball(Context c ,int x , int y , int v , int image){
super(c);
this.X = x;
this.Y = y;
this.V = v;
this.img = image;
bitmap = BitmapFactory.decodeResource(getResources(),img);
this.width = bitmap.getWidth();
this.height = bitmap.getHeight();
this.BX = (int) (x+width/2);
this.BY = (int) (y+height/2);
this.radius = width/2;
}
void setMove(double vx , double vy){
this.X = (int) BigDecimal(X+ vx);
this.Y = (int) BigDecimal(Y+ vy);
this.BX =(int) BigDecimal(BX+ vx);
this.BY =(int) BigDecimal(BY+ vy);
//invalidate();
}
void setVX_VY(double vx , double vy){
this.Vx = BigDecimal(vx);
this.Vy = BigDecimal(vy);
}
void setXY(double x , double y){
this.X = (int) BigDecimal(x);
this.Y = (int) BigDecimal(y);
this.BX = (int) BigDecimal(x+this.width);
this.BY = (int) BigDecimal(y+this.height);
}
private double BigDecimal(double e) {
// TODO Auto-generated method stub
BigDecimal bd= new BigDecimal(e).setScale(3, BigDecimal.ROUND_HALF_UP);// 小數後面四位, 四捨五入 ;
String a = ""+bd;
return Double.parseDouble(a);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint p = new Paint();
p.setColor(Color.BLACK);
canvas.drawBitmap(bitmap, (float)X,(float)Y, p);
p.setTextSize(50);
canvas.drawLine((float)BX, (float)BY, (float)(200*Vx+BX), (float)(200*Vy+BY), p);
canvas.drawCircle((float)BX,(float) BY, 10, p);
//bd=bd.setScale(4, BigDecimal.ROUND_HALF_UP);// 小數後面四位, 四捨五入
canvas.drawText(V+"",(float)BX,(float)( BY+width/2+40), p);
canvas.drawText(BX+"",(float)BX,(float)( BY+width/2+140), p);
canvas.drawText(BY+"",(float)BX,(float)( BY+width/2+240), p);
}
}我使用一個Ball[4]來存取4顆球的資料，用兩隻相同手機測試，球的座標會不一樣，希望有人可以幫忙。
