캐드에서 VBA를 이용한 세점 포물선 그리기(Drawing 3 points parabola in Autocad using VBA)

오토캐드에서 VBA로 세 점 포물선 그리는 법입니다.

Method of drawing parabola of 3points in Autocad using VBA

먼저 아래의 코드를 긁으시고

First, drag following code

Sub para()
 
    Dim Pnt1, Pnt2, Pnt3 As Variant '3points for parabola
    
    Pnt1 = ThisDrawing.Utility.GetPoint(, "1st Point")
    Pnt2 = ThisDrawing.Utility.GetPoint(, "2nd Point")
    Pnt3 = ThisDrawing.Utility.GetPoint(, "3rd Point")
 
    Dim a, b, c As Double
    Dim M11, M12, M13, M21, M22, M23, M31, M32, M33 As Double 
    Dim x1, x2, x3, y1, y2, y3, plusx, plusy As Double
 
    plusx = Pnt1(0) + Pnt3(0)
    plusy = Pnt1(1) + Pnt3(1)
 
    x1 = Pnt1(0) + plusx: x2 = Pnt2(0) + plusx: x3 = Pnt3(0) + plusx
    y1 = Pnt1(1) + plusy: y2 = Pnt2(1) + plusy: y3 = Pnt3(1) + plusy
 
    M11 = 1 / (x1 ^ 2 - x1 * x2 - x1 * x3 + x2 * x3)
    M12 = 1 / (x2 ^ 2 - x1 * x2 + x1 * x3 - x2 * x3)
    M13 = 1 / (x3 ^ 2 + x1 * x2 - x1 * x3 - x2 * x3)
 
    M21 = -(x2 + x3) / (x1 ^ 2 - x1 * x2 - x1 * x3 + x2 * x3)
    M22 = -(x1 + x3) / (x2 ^ 2 - x1 * x2 + x1 * x3 - x2 * x3)
    M23 = -(x1 + x2) / (x3 ^ 2 + x1 * x2 - x1 * x3 - x2 * x3)
 
    M31 = -(x1 * x3) * (x2 ^ 2 - x2 * x3) / (x1 ^ 2 - x1 * x3) / (x2 ^ 2 - x1 * x2 + x1 * x3 - x2 * x3)
    M32 = (x1 * x3) / (x2 ^ 2 - x1 * x2 + x1 * x3 - x2 * x3)
    M33 = -(x1 * x3) * (x2 ^ 2 - x1 * x2) / (x3 ^ 2 - x1 * x3) / (x2 ^ 2 - x1 * x2 + x1 * x3 - x2 * x3)
 
    a = M11 * y1 + M12 * y2 + M13 * y3
    b = M21 * y1 + M22 * y2 + M23 * y3
    c = M31 * y1 + M32 * y2 + M33 * y3
 
 
    Dim n As Integer '등분'
 
        n = InputBox("What is the number of divided parabola?")
 
    Dim interval As Double
 
        interval = (x3 - x1) / n
    
 
    Dim polyPnt() As Double
    ReDim polyPnt(2 * n + 1) As Double
 
    Dim i As Integer
 
    For i = 0 To n
 
        polyPnt(i * 2) = x1 + interval * i
        polyPnt(i * 2 + 1) = a * polyPnt(i * 2) ^ 2 + b * polyPnt(i * 2) + c
 
    Next i
 
    Dim Opnt1(2) As Double
    Dim Opnt2(2) As Double
 
        Opnt1(0) = 0: Opnt1(1) = 0: Opnt1(2) = 0
        Opnt2(0) = -plusx: Opnt2(1) = -plusy: Opnt2(2) = 0
 
    Dim polyObj As AcadLWPolyline
 
    Set polyObj = ThisDrawing.ModelSpace.AddLightWeightPolyline(polyPnt)
        polyObj.Move Opnt1, Opnt2
 
End Sub
 

 

Tools(도구)의 Macro - Visual Basic Editor 로 들어갑니다. Modules에서 오른쪽 마우스 누르고 Insert - Module 를 선택합니다. 빈 칸에 코드를 붙여넣습니다.

In autocad, Tools Macro - Visual Basic Editor Cursor to Modules and press right button of mouse, choice Insert - Module Paste codes in blanks

 

이제 실행만 시키면 됩니다. F5 를 누르거나 Visual Basic Editor의 초록색 화살표를 누르시고 캐드창에서 아무 곳이나 세점을 찍으면 등분을 몇개로 할 것인지를 묻을겁니다. 하고 싶은 분할 개수를 적으면 세점에 대한 포물선이 그려집니다.

Now press F5 Answer number you want and 3 points anywhere in cad window Then a parabola will be drawn

 

* VBA(Visual Basic for Aplication)를 지원하는 캐드버전이어야 합니다.

* Cad version need VBA