用Cad畫二次拋物線(共4頁)

1、精選優(yōu)質文檔-傾情為你奉上Cad畫二次拋物線如y=ax2+bx+c 第一步 確認cad中有VBA module如果沒有請下載，即CAD中“工具”“宏”“visual basic編輯器”，點thisdrawing第二步 打開cadalt+F11打開VBA窗口添加模塊復制以下 Sub pwx() '定義幾個點 Dim pntO(2) As Double Dim pntA(2) As Double Dim pntB(2) As Double Dim pntC(2) As Double Dim pntD(2) As DoubleDim pntE(2) As Double '設拋物線方程

2、為:y=ax²+bx+c Dim a As Double Dim b As Double Dim c As Double '設拋物線的寬度為l Dim l As Double Dim p As Double Dim Co As Acad3DSolid Dim Se AsAcadRegion Dim Pa As Acad3DFace Dim PntAsAcadPoint Dim Sp() As AcadObject a = InputBox("請輸入y=a*x*x+b*x+c中對應的a:", "拋物線方程參數(shù)") If a = 0 The

3、n MsgBox "a=0, 不是拋物線": End b = InputBox("請輸入y=a*x*x+b*x+c中對應的b:", "拋物線方程參數(shù)") c = InputBox("請輸入y=a*x*x+b*x+c中對應的c:", "拋物線方程參數(shù)") l = InputBox("請輸入所要畫的拋物線寬度l:", "拋物線寬度") l = l / 2 '計算x²=2py中的p p = 1 / Abs(a) '定義O點 pntO(0

4、) = 0 pntO(1) = 0 pntO(2) = 0 '定義A點 pntA(0) = 0 pntA(1) = 0 pntA(2) = l * Sqr(3) / 2 '畫圓錐 Set Co = ThisDrawing.ModelSpace.AddCone(pntO, l, l * Sqr(3) '移動圓錐,使底部圓在xy平面上 Co.MovepntO, pntA If l > p / 2 Then '定義A點 pntA(0) = 0 pntA(1) = p / 2 pntA(2) = (l - p / 2) * Sqr(3) '定義B點 pnt

5、B(0) = 0 pntB(1) = -l + p pntB(2) = 0 '定義C點 pntC(0) = 1 pntC(1) = -l + p pntC(2) = 0 '畫剝面線 Set Se = Co.SectionSolid(pntA, pntB, pntC) '剝面線旋轉到xy平面 Se.Rotate3D pntB, pntC, -60 * 4 * Atn(1) / 180'定義D點 pntD(0) = 0 pntD(1) = -l pntD(2) = 0 '定義E點 pntE(0) = 1 pntE(1) = 0 pntE(2) = 0 

6、9;移動剝面線,使頂點在(0,0,0)位置 Se.MovepntO, pntD '當a>0時,翻轉曲線 If a > 0 Then Se.Rotate3D pntO, pntE, 180 * 4 * Atn(1) / 180 '重新設E點 pntE(0) = -b / (2 * a) pntE(1) = (4 * a * c - b 2) / (4 * a) pntE(2) = 0 '移拋物線 Se.MovepntO, pntE '炸開剝面線 Sp = Se.Explode '刪除輔助內容 Co.Delete Se.Delete Sp(1).

7、Delete Else MsgBox "輸入的l太小,不適合剝圓錐" End If End Sub 第三步 菜單欄里點擊運行命令輸入?yún)?shù)abc以及拋物線寬度即可得到 一次出差到一個項目工地去,看到他們對著電腦上設計單位給的CAD圖在一個點一個點的的找坐標值.方法是用鼠標點上一個點,記下(X,Y)后再輸?shù)紼XCEL中,怕一個人出錯,得兩個人來操作. 后來有人發(fā)現(xiàn)了一個好辦法,說不用筆來記(X,Y)了,直接用復制和粘貼的辦法來做,這確實是一大進步呀.我問他們這一晚上能找多少點呀, 回答說做不了多少還老出錯. 我說這樣吧我給你編一個小程序用吧. 一晚過后第二天他們拿程序一用都說真

8、是省大勁了,又準又快呀.在CAD中 選 工具-宏-visual basic編輯器, 點thisdrawing 把下面的程序寫進去, 然后點運行即可.Attribute VB_Name = "模塊1"Sub abc()Dim x, y As DoubleDim ReturnPoint As VariantDim i As IntegerDim high As SingleDim Ptext, Fname As StringDim textObj As AcadTextDim pointObj As AcadPointDim layerObj As AcadLayerx = 0

9、: y = 0: i = 1: high = 9Fname = InputBox("選取結束時，請回到第一點！請給出文件名。")If Fname = "" Then Fname = "PointsDate"Fname = "c:abc" & Fname & ".txt"Set layerObj = ThisDrawing.Layers.Add("PointsData")ReturnPoint = ThisDrawing.Utility.GetPointPtex

10、t = i & ":(" & Round(ReturnPoint(0), 2) & "," & Round(ReturnPoint(1), 2) & ")"Set textObj = ThisDrawing.ModelSpace.AddText(Ptext, ReturnPoint, high)Set pointObj = ThisDrawing.ModelSpace.AddPoint(ReturnPoint)pointObj.Layer = "PointsData"textObj.Layer = "PointsData"pointObj.color = acRedOpen Fname For Output As