两圆相交求交点坐标.doc

两圆相交，求交点坐标最近画钣金，遇到圆相交问题，参考了网上的程序，用圆的参数方程求，下了相关程序，竟然有些点计算错误，于是决定自己重写。第二种原理是解两圆方程(x-x0)2+(yy0)2=r02(x-x1)2+(yy1)2=r12太烦了这个二元二次方程，试了好久，没弄出结果来。第三种原理是如图不需解二元二次方程，两圆相交，圆心距o0o1是知道的，割线AB距离是可求的，AB和o0o1交点Q平分AB两条线互为垂直。QB2=Bo12-Qo1QB2=Bo02 -(o0o1-Bo1)2o0o1=Qo0+Qo1可解出QB、QA、Qo0、Qo1。知道了圆心o0、o1坐标，可解出Q坐标，从而知道A、B坐标，问题求解完毕。这种方法应该是较好的，原理简单，结果正确。就用第三种方法。发现AUTOCAD内嵌了VBA，画图嘛用AUTOCAD最好了，还能编程，就用AUTOCAD2008贴几张效果图、并把相交函数贴上，因为整个VBA贴上太不方便了。参数：circle_circle功能：两圆相交，求交点坐标参数xx0 ，yy0 ，r0 第一个圆的圆心坐标，半径参数xx1 ，yy1 ，r1 第二个圆的圆心坐标，半径X_1 ,Y_1; x_2 y_2返回两个交点坐标相切情况以后加，因为我画钣金相切情况没有Sub circle_circle(ByVal xx0 As Long, ByVal yy0 As Long, ByVal r0 As Double, ByVal xx1 As Long, ByVal yy1 As Long, ByVal r1 As Double, ByRef X_1 As Long, ByRef Y_1 As Long, ByRef x_2 As Long, ByRef y_2 As Long)Dim k As Double, k1 As DoubleDim intL As DoubleDim l0 As Double, l1 As Double, lh As DoubleDim center_x As Double, center_y As DoubleDim angl As DoubleDim x0 As Double, y0 As Double, x1 As Double, y1 As Doublex0 = CDbl(xx0)y0 = CDbl(yy0)x1 = CDbl(xx1)y1 = CDbl(yy1)intL = Sqr(Pow(y1 - y0, 2) + Pow(x1 - x0, 2)l1 = (Pow(r0, 2) - Pow(r1, 2) - Pow(intL, 2) / (-2 * intL)l0 = intL - l1lh = Sqr(Pow(r1, 2) - Pow(l1, 2)Ys=KK*double(Xs-X0)+double(Y0); If (xx1 = xx0) Then 圆心垂直，交点水平对称 angl = 90 If (y1 y0) Then center_x = x0 center_y = y0 + l0 x_2 = CLng(center_x - lh) y_2 = CLng(center_y) X_1 = CLng(center_x + lh) Y_1 = CLng(center_y) Else center_x = x0 center_y = y1 + l1 x_2 = CLng(center_x - lh) y_2 = CLng(center_y) X_1 = CLng(center_x + lh) Y_1 = CLng(center_y) End If ElseIf (yy1 = yy0) Then 圆心水平，交点垂直对称 If (x1 x0) Then center_x = x0 + l0 center_y = y0 x_2 = CLng(center_x) y_2 = CLng(center_y - lh) X_1 = CLng(center_x) Y_1 = CLng(center_y + lh) Else center_x = x1 + l1 center_y = y1 x_2 = CLng(center_x) y_2 = CLng(center_y - lh) X_1 = CLng(center_x) Y_1 = CLng(center_y + lh) End If Else 圆心no水平no垂直， k = (y1 - y0) / (x1 - x0) angl = Atn(k) If (x1 x0) Then center_x = x0 + l0 * Cos(angl) center_y = y0 + l0 * Sin(angl) Else center_x = x1 + l1 * Cos(angl) center_y = y1 + l1 * Sin(angl) End If x_2 = CLng(center_x + lh * Sin(angl) y_2 = CLng(cent