已知三点坐标，求外接圆半径与圆心坐标

jackgan

数控加工定位时用到，随便测内孔上三点坐标就可得出孔半径和圆心坐标


这个有点象坐标测量机测量用的


请大侠做成VBA格式


THANK！！

PS122

Public Function GetCenOf3Pt(pt1 As Variant, pt2 As Variant, pt3 As Variant, _
ByRef radius As Double) As Variant

Dim xysm, xyse, xy As Double
Dim ptCen(2) As Double

xy = pt1(0) ^ 2 + pt1(1) ^ 2
xyse = xy - pt3(0) ^ 2 - pt3(1) ^ 2
xysm = xy - pt2(0) ^ 2 - pt2(1) ^ 2
xy = (pt1(0) - pt2(0)) * (pt1(1) - pt3(1)) - (pt1(0) - pt3(0)) * (pt1(1) - pt2(1))

'判断参数有效性
If Abs(xy) < 0.000001 Then
MsgBox "所输入的参数无法创建圆形！"
Exit Function
End If

'获得圆心和半径
ptCen(0) = (xysm * (pt1(1) - pt3(1)) - xyse * (pt1(1) - pt2(1))) / (2 * xy)
ptCen(1) = (xyse * (pt1(0) - pt2(0)) - xysm * (pt1(0) - pt3(0))) / (2 * xy)
ptCen(2) = 0
radius = Sqr((pt1(0) - ptCen(0)) * (pt1(0) - ptCen(0)) + (pt1(1) - ptCen(1)) * (pt1(1) - ptCen(1)))

If radius < 0.000001 Then
MsgBox "半径过小！"
Exit Function
End If

'函数返回圆心的位置，而半径则在参数中通过引用方式返回
GetCenOf3Pt = ptCen
End Function

BDYCAD

这样来可以搞掂吧:


        先在这三个点画出弧 再取出圆心和半径.


(COMMAND ".ARC" 第一点 第二点 第三点)


        (SETQ S-ARC(ENTLAST));选到刚画的弧


(SETQ ARC-DXF (ENTGET S-ARC)); 弧的DXF组码


(SETQ ARC-CENTER (CDR (ASSOC 10 ARC-DXF)));圆心点提取


(SETQ RADIUS (CDR (ASSOC 40 ARC-DXF))); 半径提取

jackgan

我想这样，在输入三个点的座标后能自动计算出圆心座标及其半径





       


THANK！！老大

BDYCAD

; 编程: 包达勇
; 日期: 2004-11-08
; 功能: 取三个不在同一直线点唯一的圆弧半径和圆心
; 用法 (setq ARC-CR(B:GET-ARCenter-Radius <起点> <中点> <终点>))
; 返回值 ( <半径> <圆心点> )
(defun B:GET-ARCenter-Radius (SP MP EP / ARC-CENTER ARC-CP ARC-RADIUS BD-1 BD-2 BF-1 BF-2)
(setq bd-1 (polar SP (angle SP MP) (* 0.5 (DISTANCE SP MP)))
bd-2 (polar EP (angle EP MP) (* 0.5 (DISTANCE EP MP)))
bf-1 (polar bd-1 (+ (* 0.5 pi)(angle SP MP)) 10.0)
bf-2 (polar bd-2 (+ (* 0.5 pi)(angle EP MP)) 10.0)
ARC-Center (inters bd-1 bf-1 bd-2 bf-2 NIL)
ARC-Radius (DISTANCE MP ARC-CP))
(list ARC-Radius ARC-Center ))

jackgan

不好意思我看不懂LISP


只会VBA

noyesnono

写成EXE可以么？

434939575

BDYCAD 发表于 2005-2-20 08:48
; 编程: 包达勇; 日期: 2004-11-08; 功能: 取三个不在同一直线点唯一的圆弧半径和圆心; 用法                                         (setq AR ...

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