两圆求交点算法实现Java代码

//将两个圆融合在一个对象中进行相交 public class CirIntersect { private Circle c1=null; private Circle c2=null; private double x1; private double y1; private double x2; private double y2; private double r1; private double r2; public CirIntersect(Circle C1,Circle C2){ c1= C1; c2= C2; x1=c1.getX(); y1=c1.getY(); x2=c2.getX(); y2=c2.getY(); r1=c1.getR(); r2=c2.getR(); //初始化时将交点坐标设置为两圆圆心， } public void intersect(){ double a,b,d,y_1,y_2,x_1,x_2; double delta = -1; y_1=y1; y_2=y2; x_1=x1; x_2=x2; //解一元二次方程 if(x1!=x2){ //式①减式②带入式①，得到二次方程。 a=Math.pow((2*y1 - 2*y2)/(2*x1 - 2*x2),2) + 1;//((y2-y1)*(y2-y1))/((x2-x1)*(x2-x1))+1;//for y b=((4*y1 - 4*y2)*(x1 + (r1*r1 - r2*r2 - x1*x1 + x2*x2 - y1*y1 + y2*y2)/(2*x1 - 2*x2)))/(2*x1 - 2*x2) - 2*y1;//(y2-y1)*(-r2*r2+r1*r1-y1*y1+y2*y2+x2*x2-x1*x2)/((x2-x1)*(x2-x1))-2*y1; d=Math.pow((x1 + (r1*r1 - r2*r2 - x1*x1 + x2*x2 - y1*y1 + y2*y2)/(2*x1 - 2*x2)),2) - r1*r1 + y1*y1;//(Math.pow((-r2*r2+r1*r1-y1*y1+y2*y2+x2*x2-x1*x2)/(2*(x2-x1)),2)+y1*y1-r1*r1); //下面使用判定式 判断是否有解 delta=b*b-4*a*d; if(delta >0){ y1=(-b+Math.sqrt(b*b-4*a*d))/(2*a); y2=(-b-Math.sqrt(b*b-4*a*d))/(2*a); x1=(r2*r2-r1*r1+y_1*y_1-y_2*y_2+x_1*x_1-x_2*x_2-2*(y_2-y_1)*y1)/(2*(x_2-x_1)); x2=(r2*r2-r1*r1+y_1*y_1-y_2*y_2+x_1*x_1-x_2*x_2-2*(y_2-y_1)*y2)/(2*(x_2-x_1)); } else if(delta ==0){//x needs another delta too y1=y2=-b/(2*a); x1=x2=(r2*r2-r1*r1+y_1*y_1-y_2*y_2+x_1*x_1-x_2*x_2-2*(y_2-y_1)*y2)/(2*(x_2-x_1)); }else{ ; } System.out.println("x_1:"+x_1+" y_1:"+y_1+'\n'+" x_2:"+x_2+" y_2:"+y_2+"\nr1:"+r1+" r2:"+r2+" \nx1:" +x1+" y1:"+y1+'\n'+" x2:"+x2+" y2:"+y2+"\n delta"+delta+"\n a"+a+"\n b"+b+"\n d"+d); } else{ a=Math.pow((2*x1 - 2*x2)/(2*y1 - 2*y2),2) + 1;//((x2-x1)*(x2-x1))/((y2-y1)*(y2-y1))+1;//for x b=((4*x1 - 4*x2)*(y1 + (r1*r1 - r2*r2 - y1*y1 + y2*y2 - x1*x1 + x2*x2)/(2*y1 - 2*y2)))/(2*y1 - 2*y2) - 2*x1;//(x2-x1)*(-r2*r2+r1*r1-x1*x1+x2*x2+y2*y2-y1*y2)/((y2-y1)*(y2-y1))-2*x1; d=Math.pow((y1 + (r1*r1 - r2*r2 - y1*y1 + y2*y2 - x1*x1 + x2*x2)/(2*y1 - 2*y2)),2) - r1*r1 + x1*x1;//(Math.pow((-r2*r2+r1*r1-x1*x1+x2*x2+y2*y2-y1*y2)/(2*(y2-y1)),2)+x1*x1-r1*r1) delta=b*b-4*a*d; if(delta >0){ x1=(-b+Math.sqrt(b*b-4*a*d))/(2*a); x2=(-b-Math.sqrt(b*b-4*a*d))/(2*a); y1=(r2*r2-r1*r1+x_1*x_1-x_2*x_2+y_1*y_1-y_2*y_2-2*(x_2-x_1)*x1)/(2*(y_2-y_1)); y2=(r2*r2-r1*r1+x_1*x_1-x_2*x_2+y_1*y_1-y_2*y_2-2*(x_2-x_1)*x2)/(2*(y_2-y_1)); } else if(delta ==0){//y needs another delta too x1=x2=-b/(2*a); y1=y2=(r2*r2-r1*r1+x_1*x_1-x_2*x_2+y_1*y_1-y_2*y_2-2*(x_2-x_1)*x2)/(2*(y_2-y_1)); }else{ ; } System.out.println("x_1:"+x_1+" y_1:"+y_1+'\n'+" x_2:"+x_2+" y_2:"+y_2+"\nr1:"+r1+" r2:"+r2+" \nx1:" +x1+" y1:"+y1+'\n'+" x2:"+x2+" y2:"+y2+"\n delta"+delta+"\n a"+a+"\n b"+b+"\n d"+d); } } }