这个真是个难题,现在我把下载的一个做法提供给大家,供参考
# Y# i2 g0 Y* r6 W% k! j1.先用直线命令画一直线(图1)。过程如下:3 x* ~" U/ r; P4 B* y$ q
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命令: LINE5 \# v7 v% W: g6 E% c
指定第一点: 0,0
; a; z7 D$ M h* D: o6 W7 y 指定下一点或 [放弃(U)]: 'cal
$ R& D8 [$ _ Q* Z8 U+ ` >> 表达式: +[100*100/200<-30]
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指定下一点或 [放弃(U)]: ↙
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2.移动该直线,如图2。
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3.用多段线命令画多段线,先向-60度方向拉出适当长度,如图3。5 Q+ g7 B/ Y& v* c, ]# u- A
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4.继续画多段线,完成一个直角三角形,如图4。- Y* Z$ y2 N9 p1 \6 w
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5.用REVOLVE命令旋转直角三角形,生成一个三维实体,如图5。过程如下:- b6 Y2 u# }3 Z* u: T! {
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命令: REVOLVE
- Z& J2 v1 A+ H4 e# [ H! g 当前线框密度: ISOLINES=4
- u+ p* O9 |/ Y/ Z; j# q7 J9 \ 选择对象:(选择直角三角形)
, ~' q% e3 ]; Y/ f 选择对象: ↙
6 R2 C, @6 Q) V2 s 指定旋转轴的起点或
- x# ^8 o" c8 k* A2 g- u 定义轴依照 [对象(O)/X 轴(X)/Y 轴(Y)]:(捕捉A点)
, @. c' a3 b4 _ x; `+ C1 A! C 指定轴端点: (捕捉B点)1 p- J% a, }6 C9 y) y
指定旋转角度 <360>:↙7 ?6 j8 d* k2 D$ i
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6.用SECTION命令切割三维实体,生成一个面域,如图6。过程如下:
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命令: SECTION T7 ^$ T" \7 O6 E7 L3 K. O" o
选择对象: (选择上一步生成的旋转实体)
F8 I. C6 f. [0 q 选择对象: ↙
# `5 z/ W: ~ }0 }- Z0 p9 O 指定截面上的第一个点,依照 [对象(O)/Z 轴(Z)/视图(V)/XY 平面(XY)/YZ 平面(YZ)/ZX 平面(ZX)/三点(3)] <三点>: yz) L0 C9 E- a4 c# x# W! _
指定 YZ 平面上的点 <0,0,0>:(捕捉C点)
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9 K+ \! a5 S% z% v' c; ?9 g: J 7.用rotate3d命令对上一步生成的面域进行三维旋转,如图7。过程如下:$ W$ u% v3 J% L' N6 U. ^
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命令: rotate3d2 l& Y! u. |) g5 G8 {* t
当前正向角度: ANGDIR=逆时针 ANGBASE=0$ t r: D. U4 v9 B& [( Z
选择对象: (选择上一步生成的面域)
8 N- D2 l9 R6 X' S- e" W2 G+ K 选择对象: ↙
; n: a' @0 R5 g5 c k. g 指定轴上的第一个点或定义轴依据[对象(O)/最近的(L)/视图(V)/X 轴(X)/Y 轴(Y)/Z 轴(Z)/两点(2)]: (捕捉C点) 指定轴上的第二点:(捕捉D点); K: B$ l* E1 }4 n' u
指定旋转角度或 [参照(R)]: 90) y4 q% X P1 j1 q' N2 ~/ O \) M
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* }# D! Y% h( b 8.先用EXPLODE命令分解旋转后的面域,再清理图面,删除不需要的图元,如图8。
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- X) [. C7 F" Y, a6 V 9.移动抛物线,如图9。完毕!: v! S, T3 c0 ^0 [2 p3 C; O
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http://bbs.icax.cn/register.php
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0 V+ l2 L* H( j+ r0 \! I3 m9 |Sub trparabola() 8 q# X& W1 l: M, B6 a
Dim bq1, bq2, pt1, pt2 As Variant
, V" S! G' D% D+ O- D. vDim aa, ll, yy, a1, a2, a3, a4, aa1, pt3(0 To 2), bq4(0 To 2) As Double
' _' r) \8 j8 \- }$ iDim bq3(0 To 2) As Double 6 a, [4 D2 M( {- ^! U1 n
Dim ae As Double
( E' `+ c4 a3 k& \Dim pt33(0 To 2) As Double
/ _, e* K/ I9 W, U9 w/ ADim ptarr(0 To 7) As Double 1 a G# m H5 K" G$ ~
Dim alt As Variant 4 a4 ]6 ]& l' `& p5 U1 H' P
Dim objboltb As Acad3DSolid # e1 T/ T7 V9 S( o) T' ~+ H
Dim al As Variant
' `5 j+ x6 h( E" ^; mDim lens As AcadLWPolyline
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'求个控制点
' c. g: \5 M$ ?5 l+ u9 Kbq1 = ThisDrawing.Utility.GetPoint(, "抛物线顶点: ") 2 \5 f3 G, k8 t! m5 o6 z
aa = ThisDrawing.Utility.GetReal("输入二次项系数: ") & k# y e1 I% o
ll = ThisDrawing.Utility.GetDistance(, "输入开口弦长: ") . i/ G8 }8 \3 ]+ R" A4 m
aa1 = 1 / aa
- y$ H. j/ ~+ u) s8 ?yy = aa * (ll / 2) ^ 2
3 G& N" q6 y5 u% N- _2 D! S, na1 = ThisDrawing.Utility.AngleToReal(-30, acDegrees) # P, J/ S6 I/ H. M- i
a2 = ThisDrawing.Utility.AngleToReal(30, acDegrees) 0 s7 R$ }0 \4 S4 s
a3 = ThisDrawing.Utility.AngleToReal(90, acDegrees)
) ~9 L3 E& t1 v; Q! G I, qa4 = ThisDrawing.Utility.AngleToReal(150, acDegrees) $ t. g3 e( u5 `
bq2 = ThisDrawing.Utility.PolarPoint(bq1, a2, yy)
+ X! N& |( N) z% I Zpt1 = ThisDrawing.Utility.PolarPoint(bq1, a4, aa1)
& s8 m2 }3 v1 D$ u' s4 s- {pt2 = ThisDrawing.Utility.PolarPoint(bq2, a3, aa1)
, y( K8 k% G4 {( v/ M" m9 x3 [9 ~/ npt3(0) = pt2(0): pt3(1) = pt1(1): pt3(2) = pt1(2)
, y. c/ u) o: S bbq3(0) = bq2(0): bq3(1) = bq2(1): bq3(2) = bq2(2) + 10 9 D1 D7 T' r% c( D* L' X2 s, Z
bq4(0) = bq2(0): bq4(1) = bq1(1): bq4(2) = bq1(2) : u" m3 m( P7 ^# }0 Z3 v
pt33(0) = 10: pt33(1) = 0: pt33(2) = 0
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ptarr(0) = pt1(0)
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ptarr(2) = pt2(0)
; T! h- u8 l# cptarr(3) = pt2(1) 8 A. b; L+ N. O% U6 j
ptarr(4) = pt3(0)
) g9 Z8 h) ]) w( r9 \# v* R' gptarr(5) = pt3(1) * Q/ s/ W" C* b# T$ q0 b' ^
ptarr(6) = pt1(0)
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8 k$ [9 O' z/ I# s- L' Z9 ?8 ]'画多段线
1 k& v n1 \8 O% fSet lens = ThisDrawing.ModelSpace.AddLightWeightPolyline(ptarr) 3 i6 c I3 _0 ~; Z& i {
Dim objlist(0) As AcadEntity 9 W8 S$ h: W; L& {- B
Set objlist(0) = lens : V* T* l4 t. d# \. \
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'将多段线变为面域 . ^. u% k2 J& E0 ^( l6 G$ `
Dim altregion As AcadRegion 3 {2 A' \: R$ x* q* L
alt = ThisDrawing.ModelSpace.AddRegion(objlist)
0 ` N' {# n# V$ j9 y- m' K Sobjlist(0).Delete
# \* H: ~1 s% b C$ m# H7 n* E) ISet altregion = alt(0)
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'旋转面域得到圆锥 " b' [" X) Y# @" ?# y9 _ B5 ~, W
ae = 2 * Atn(1) * 4
3 a8 p# `4 Q% j7 t8 b* x9 LSet objboltb = ThisDrawing.ModelSpace.AddRevolvedSolid(altregion, pt1, pt33, ae)
5 G6 N4 D& e# h" A5 Galtregion.Delete 4 e w. a1 k t6 c# i; C
' G, g! O2 U+ P% D: I'切圆锥得到抛物线 % I6 _) p" P: V3 k# g* U% H( ]
Set al = objboltb.SectionSolid(bq1, bq2, bq3) + d9 _6 q" i& z6 h+ X! A
objboltb.Delete
! x9 Z4 y W" Z. X6 qal.Rotate bq1, a1 9 U! Z E o$ t. \! k
al.Rotate3D bq1, bq4, a3
: e( L* Y, {. T( Q! j, UDim explodedobjects As Variant
% I( `: s/ Z% yexplodedobjects = al.Explode _0 N l2 t; V1 H
al.Delete
: R& S" Z7 N& J) p9 ~Dim i As Integer
3 s0 O$ q( w" z# y" ]$ [Dim kind As String ; {' A/ c. h8 Z
Dim parabolaobject As AcadSpline
0 X, G$ V" B) A8 R. EFor i = 0 To UBound(explodedobjects) + e* F3 e3 x G& F
kind = explodedobjects(i).ObjectName - f3 x8 l6 d# R+ F
If kind = "AcDbLine" Then
( [' j& y1 C. v, I7 S explodedobjects(i).Delete
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$ F# A5 i! N. C+ o, e" F Set parabolaobject = explodedobjects(i) 9 h- [2 S: `) n' U0 S
End If
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'旋转抛物线
' [" ]6 p' H9 }0 A. ]- c" UThisDrawing.SendCommand "rotate" & vbCr & "(Handent """ & parabolaobject.Handle & """)" & vbCr & "" & vbCr & bq1(0) & "," & bq1(1) & vbCr : S2 l) B2 D5 m( C9 [
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End Sub1 D7 I S# ]6 [* N+ _
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