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
5 F& g! K' w6 a7 n* D1.先用直线命令画一直线(图1)。过程如下:
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/ v* }. L5 G! m1 v 命令: LINE
6 Y. c0 U. w6 K* I+ l. G$ g 指定第一点: 0,0
+ M2 F# ?8 I$ ^9 e% _! w 指定下一点或 [放弃(U)]: 'cal
( f* E A. H9 c1 W# q* a' a >> 表达式: +[100*100/200<-30]
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指定下一点或 [放弃(U)]: ↙2 H h2 k& d+ X/ Z. l& k
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9 t7 T( P6 {4 h6 l7 Z/ g0 P. B6 ] 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。. A% P/ b8 w& |
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' t5 [7 X. ` N, D 4.继续画多段线,完成一个直角三角形,如图4。3 j( T: s! J5 m" s
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. H1 Z" y) ]' [* @& t$ o' C& b6 @ 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:- k( c+ D( L" t1 P
, y, T& ?3 `" w5 F/ j8 y: O7 n4 C 命令: REVOLVE
+ Y3 D( P/ H0 W2 {' e" D 当前线框密度: ISOLINES=4
( F! F) r: _, N 选择对象:(选择直角三角形)
, ?5 V( O" g# |/ S, k 选择对象: ↙8 M* B1 a* x9 Y) H6 ^6 h. Q& s/ @
指定旋转轴的起点或0 ?; ~+ O; o' @0 P. d5 `
定义轴依照 [对象(O)/X 轴(X)/Y 轴(Y)]:(捕捉A点), `6 C/ B4 W$ p; e. e& U2 h" `8 e
指定轴端点: (捕捉B点)( `2 o/ M: `, G' \! ~( N" M
指定旋转角度 <360>:↙" E5 {- u2 t- z7 v4 ]7 l
) s8 [) w# q$ _5 c" Y 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
E* p$ ~0 |& ^- [' N0 k& {+ K+ U8 }8 [ 选择对象: (选择上一步生成的旋转实体)# v) ^2 N( v$ y# D4 o
选择对象: ↙4 ~9 b" c2 c) C v1 `/ T: 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>: yz6 H5 D4 L/ r$ u. x7 U' M
指定 YZ 平面上的点 <0,0,0>:(捕捉C点)
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% Z. U$ [9 r: N! `5 J9 Y- ^- f 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:
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命令: rotate3d
& J% Z- i8 k3 _: h 当前正向角度: ANGDIR=逆时针 ANGBASE=09 S) K# ?) q0 N0 s1 I3 X$ k& ]
选择对象: (选择上一步生成的面域)
9 a1 Z5 V! P( t( X( h, V 选择对象: ↙; }* x" e$ Y2 C( e/ O" s! k* `) V; \0 z
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)
8 f% `4 J! e2 d/ h0 u7 ]* R 指定旋转角度或 [参照(R)]: 90
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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。& e4 L* m$ ^& ~
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9.移动抛物线,如图9。完毕!
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9 X: ^' P4 ]' x. h8 ^Sub trparabola() 8 ?9 B+ D/ p9 T& K8 O
Dim bq1, bq2, pt1, pt2 As Variant 2 S, t% m# X% P8 |
Dim aa, ll, yy, a1, a2, a3, a4, aa1, pt3(0 To 2), bq4(0 To 2) As Double
7 X, y5 D) K3 @1 oDim bq3(0 To 2) As Double 3 F Q) E: A! p/ @( S2 c( F
Dim ae As Double
9 ?* m& X5 o% D, cDim pt33(0 To 2) As Double
C4 w) D* g8 P& x1 sDim ptarr(0 To 7) As Double
# o5 w1 [( ]$ | N+ \Dim alt As Variant % v: C1 R$ D* z' J4 N
Dim objboltb As Acad3DSolid ( J/ ^1 [, F3 D0 b ^0 d1 S
Dim al As Variant
5 m4 u5 d0 z8 b: W4 A0 i6 CDim lens As AcadLWPolyline 5 v4 b e( k& ?: }" M
2 \3 g: C# g4 x) z) d'求个控制点
/ j1 x+ a9 z$ ~! s! J1 O8 jbq1 = ThisDrawing.Utility.GetPoint(, "抛物线顶点: ") ; \& ~* o% l/ ? |. A
aa = ThisDrawing.Utility.GetReal("输入二次项系数: ")
& f) x' b! Q3 \1 F2 n+ wll = ThisDrawing.Utility.GetDistance(, "输入开口弦长: ")
& R5 L% ^, R( ~/ x3 Q6 }aa1 = 1 / aa
# B& J) Y: P8 o, U$ kyy = aa * (ll / 2) ^ 2
+ n: ]9 H- l$ ~/ Ja1 = ThisDrawing.Utility.AngleToReal(-30, acDegrees)
1 @2 C7 {( F5 Ca2 = ThisDrawing.Utility.AngleToReal(30, acDegrees) ! n: a' [; s- ?) g+ |! a
a3 = ThisDrawing.Utility.AngleToReal(90, acDegrees) ! U; e- M- D3 h) ^
a4 = ThisDrawing.Utility.AngleToReal(150, acDegrees)
7 Z: S) M; b+ K3 U) dbq2 = ThisDrawing.Utility.PolarPoint(bq1, a2, yy) ( L2 L/ F5 c: E( {( T- `( s
pt1 = ThisDrawing.Utility.PolarPoint(bq1, a4, aa1)
- G5 I: I1 R( F$ [2 K) ]' |pt2 = ThisDrawing.Utility.PolarPoint(bq2, a3, aa1)
1 M: w5 K0 N5 M! J! E) _/ K6 D1 u ]pt3(0) = pt2(0): pt3(1) = pt1(1): pt3(2) = pt1(2) , b/ Z$ F' j( L. @
bq3(0) = bq2(0): bq3(1) = bq2(1): bq3(2) = bq2(2) + 10 . w# I9 k1 d6 @
bq4(0) = bq2(0): bq4(1) = bq1(1): bq4(2) = bq1(2) . R: Q! T* J% o7 ~0 H
pt33(0) = 10: pt33(1) = 0: pt33(2) = 0 / [, J8 ~2 r! ~, s! N5 z
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# n$ ?0 L& s1 f4 P# r& U1 hptarr(0) = pt1(0) ! x9 w2 {; T4 d! x' h
ptarr(1) = pt1(1) # |- e+ h$ M+ u w5 k' |7 s' E$ Z; s
ptarr(2) = pt2(0)
% r# n: {0 z) r# b" k2 u/ S+ Sptarr(3) = pt2(1)
' O) F2 c4 W# v7 ~/ s7 O. xptarr(4) = pt3(0) : n- Z/ i2 b5 {* z9 _/ f$ ?: v( z
ptarr(5) = pt3(1) , x! @! w V9 B! G4 d H/ q$ q
ptarr(6) = pt1(0) 2 y+ z$ R1 H1 L6 ~' a
ptarr(7) = pt1(1) 6 f/ ?0 D# q; _/ y7 z
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'画多段线
u( q$ ?! A( d% N; F7 @Set lens = ThisDrawing.ModelSpace.AddLightWeightPolyline(ptarr) : f1 }* u+ O2 R! {' q* O
Dim objlist(0) As AcadEntity 7 T& D5 v- s2 A( b1 L
Set objlist(0) = lens
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'将多段线变为面域 0 J$ z9 u1 `" C
Dim altregion As AcadRegion
7 d% w6 n/ @* O3 Zalt = ThisDrawing.ModelSpace.AddRegion(objlist)
( ]% |8 h# [9 ~7 e7 W- D- Robjlist(0).Delete
: o# X; r& h7 i( E2 @$ E" HSet altregion = alt(0)
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'旋转面域得到圆锥 ! N# c1 f" w9 O( r: c* k, p4 T
ae = 2 * Atn(1) * 4 4 q; B( n6 s. F( P
Set objboltb = ThisDrawing.ModelSpace.AddRevolvedSolid(altregion, pt1, pt33, ae) 0 o' p, L: h- r, V& U, l
altregion.Delete 7 q4 n: p4 f. m6 M
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'切圆锥得到抛物线 6 Y2 ?; ?+ K: O K/ o5 Q( T' X) S
Set al = objboltb.SectionSolid(bq1, bq2, bq3) 7 I2 @' [4 _$ s. X- m5 ]8 b
objboltb.Delete
) @. \8 L" D1 q9 e1 [4 d1 eal.Rotate bq1, a1 ' t8 X2 K3 M7 }! j
al.Rotate3D bq1, bq4, a3
) G1 V0 V- C( @( }3 H& UDim explodedobjects As Variant 6 x) J) K) L) }9 b
explodedobjects = al.Explode
% f# n5 i! ]- U* p3 r! Bal.Delete 0 X5 k$ e6 x: L7 d- s% l
Dim i As Integer ; }2 g$ E; D# B
Dim kind As String / K: m) b" q0 }* m2 y* X
Dim parabolaobject As AcadSpline
( ^' W7 p' ?1 F( p F# eFor i = 0 To UBound(explodedobjects)
* Z* ]3 T; O* jkind = explodedobjects(i).ObjectName
6 f0 s8 {+ w1 R$ CIf kind = "AcDbLine" Then : {8 c; f3 r+ k7 h
explodedobjects(i).Delete 7 M1 g0 N- k- M: k( P z1 o
Else
F2 q& S& f1 D" m o0 u3 i: e1 u Set parabolaobject = explodedobjects(i) & u( B, j5 X8 [% I
End If
0 }3 T+ Y7 B; n3 |Next
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'旋转抛物线
- P2 q# }3 I( g; n u1 @ThisDrawing.SendCommand "rotate" & vbCr & "(Handent """ & parabolaobject.Handle & """)" & vbCr & "" & vbCr & bq1(0) & "," & bq1(1) & vbCr
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End Sub! v4 J0 `1 K. H
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