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( \8 ~9 B8 L9 q3 A- P* o% X- N3 @
1.先用直线命令画一直线（图1）。过程如下：
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; j- C% p! H) R" B! m 命令: LINE1 _: w! j0 Q# W6 j
指定第一点: 0,0# ]3 }% p9 k" W6 |# x
指定下一点或 [放弃(U)]: 'cal
/ p+ _/ Z/ \' V! w* |2 d >> 表达式: +[100*100/200<-30]
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! }8 r& X2 e2 |4 Q3 E) n" a 指定下一点或 [放弃(U)]: ↙3 \" n! N) L* Z7 o0 ?! W( h6 m
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1 l: A: \) \2 ~. j$ r 2.移动该直线，如图2。, H; c& p' ^5 V7 V' J
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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。" ~. J" W7 E& e! c5 M3 l, `+ x3 E1 E
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4.继续画多段线，完成一个直角三角形，如图4。
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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：
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命令: REVOLVE
3 l7 V( c0 ]4 J3 a8 X. K 当前线框密度: ISOLINES=4( Z8 f9 o' N7 e' u
选择对象:（选择直角三角形）8 }& @! |. P( s. u* G3 P
选择对象: ↙
p+ ?. e) i+ ?8 p 指定旋转轴的起点或1 Y- B! S9 {, n; e
定义轴依照 [对象(O)/X 轴(X)/Y 轴(Y)]:（捕捉A点）
! `4 h& O, ^( n 指定轴端点: （捕捉B点）
1 A# y2 s3 q* r( p0 S; [ 指定旋转角度 <360>:↙2 U3 I; k5 A ]5 R- J9 d6 `
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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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7 F4 _4 h5 S1 X' A% F2 l 命令: SECTION% E: ?* W# I0 D* j" @5 f+ V
选择对象: (选择上一步生成的旋转实体)
M% L3 n8 Z4 T+ U! K8 T* n 选择对象: ↙' W$ |% U/ P; a% u
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* i1 x: H6 O3 s0 T: X' Z
指定 YZ 平面上的点 <0,0,0>:（捕捉C点）. }# K( p H3 c7 O" y$ }2 ^
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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：, l2 M* O/ K; q9 K- C( [
- q% x4 @: P% s: d9 z6 a" n 命令: rotate3d4 m; I/ S* u' D
当前正向角度: ANGDIR=逆时针 ANGBASE=0& T7 o! ^9 o9 @* F. [
选择对象: （选择上一步生成的面域）9 Q8 O9 W; i( f# M9 Y) w
选择对象: ↙6 m( B0 X% C& c! O2 t1 R5 A( S
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）1 s7 [- Z3 h+ C) Z& E9 c( O3 O
指定旋转角度或 [参照(R)]: 90
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+ r! }- Y. Z; R( q" @7 m0 Y4 O C8 \ 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。) c) F- U2 M/ A0 m/ q" Q( T
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9.移动抛物线，如图9。完毕！5 g- P, C" v& E+ E9 a
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" Z9 s) d: H! T$ Mhttp://bbs.icax.cn/register.php
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( |) H% j( U4 p* w5 v; O' k( X& BSub trparabola()
! m4 S3 ~9 R+ }# eDim bq1, bq2, pt1, pt2 As Variant
c9 L8 w+ H* O+ G, xDim aa, ll, yy, a1, a2, a3, a4, aa1, pt3(0 To 2), bq4(0 To 2) As Double 4 w8 u- X& _# I; u6 o
Dim bq3(0 To 2) As Double , H' ?' P! O1 ?
Dim ae As Double
/ }: |# O2 ` F! y; UDim pt33(0 To 2) As Double
% E" Z3 E; r, I+ r/ I0 ^9 H% aDim ptarr(0 To 7) As Double
1 ~' q; g7 U- X3 PDim alt As Variant
8 |2 g& z& q. x1 NDim objboltb As Acad3DSolid / V7 L7 j0 v1 G$ U/ |# h1 Q
Dim al As Variant
* e: ?, ~% J* e* m2 iDim lens As AcadLWPolyline 1 q8 P4 d# c; T1 c& N& _
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'求个控制点 3 b: o: x$ C" r& i
bq1 = ThisDrawing.Utility.GetPoint(, "抛物线顶点: ")
' f. o* \4 L$ ^aa = ThisDrawing.Utility.GetReal("输入二次项系数： ")
1 A' ?+ B* l7 D% v, Qll = ThisDrawing.Utility.GetDistance(, "输入开口弦长： ")
2 v; c6 q6 b) ]/ j. Jaa1 = 1 / aa
8 q, Z. i% X+ u* ^; hyy = aa * (ll / 2) ^ 2 - U! Q3 x8 l! l
a1 = ThisDrawing.Utility.AngleToReal(-30, acDegrees)
6 k! |" P4 ?/ O! ?a2 = ThisDrawing.Utility.AngleToReal(30, acDegrees) 4 @% ?) ~2 W8 A/ O9 j" h% `+ }& t B' \
a3 = ThisDrawing.Utility.AngleToReal(90, acDegrees)
: I- v8 h* C. ]- fa4 = ThisDrawing.Utility.AngleToReal(150, acDegrees) - L3 q2 r: z$ \* W
bq2 = ThisDrawing.Utility.PolarPoint(bq1, a2, yy)
% @0 Q$ }; o! Q* n7 lpt1 = ThisDrawing.Utility.PolarPoint(bq1, a4, aa1)
+ f$ v7 e E0 }6 K: mpt2 = ThisDrawing.Utility.PolarPoint(bq2, a3, aa1)
' x( |9 t& Y4 P* M ]/ e* Ppt3(0) = pt2(0): pt3(1) = pt1(1): pt3(2) = pt1(2)
0 G( `' i" A# u/ Y* ?. p/ B* Jbq3(0) = bq2(0): bq3(1) = bq2(1): bq3(2) = bq2(2) + 10
) F9 j5 D% ~( X1 \2 m _3 s2 J7 obq4(0) = bq2(0): bq4(1) = bq1(1): bq4(2) = bq1(2) 7 W+ h$ n4 `, `, h$ W0 T- k
pt33(0) = 10: pt33(1) = 0: pt33(2) = 0
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+ t- |4 V0 j7 T7 ?3 |4 X9 yptarr(0) = pt1(0)
i2 e% |( z6 p$ [- v" Zptarr(1) = pt1(1)
7 c' X- e A- ~ptarr(2) = pt2(0)
c; i* T: E$ k5 W Dptarr(3) = pt2(1) 7 a, |$ @& G: x' N
ptarr(4) = pt3(0) * n. m! r! x9 P+ z
ptarr(5) = pt3(1) 4 q0 T. d2 v; ^9 f. {8 }
ptarr(6) = pt1(0) 6 R k4 r& H+ }; C- I
ptarr(7) = pt1(1) 3 E0 X; m! \, a0 H% e% k- d O4 D
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'画多段线 * P3 F5 k. |8 G( h6 O
Set lens = ThisDrawing.ModelSpace.AddLightWeightPolyline(ptarr)
3 M& J# B- l5 @, rDim objlist(0) As AcadEntity
! q$ u2 I6 b- F$ Q2 }$ x& [0 w2 qSet objlist(0) = lens ' Z( L; p, i) t# b( C& Y
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'将多段线变为面域
A d6 H' X* a* A# q: v/ o; vDim altregion As AcadRegion * w, m% m4 \" v `3 Z
alt = ThisDrawing.ModelSpace.AddRegion(objlist)
! i/ c3 P+ v6 ~! C {+ lobjlist(0).Delete * Z7 A- N9 b5 V+ E2 I% E, j
Set altregion = alt(0)
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, e. w% o' O3 o5 Y9 _/ B'旋转面域得到圆锥 * G% \3 m; O+ G* k" f
ae = 2 * Atn(1) * 4 - O% s, ?1 z9 C* u/ n7 ?& s
Set objboltb = ThisDrawing.ModelSpace.AddRevolvedSolid(altregion, pt1, pt33, ae)
- L8 c4 L: @' Haltregion.Delete & q B+ p7 T# l: [2 i7 L& O) ]
1 {& z4 u! _7 R4 [. j: `! ]7 v5 G3 F'切圆锥得到抛物线
, {: B* ^) m5 g9 ]Set al = objboltb.SectionSolid(bq1, bq2, bq3)
3 B9 `7 [) A! Z5 W4 S2 kobjboltb.Delete
; h7 M4 H0 ~, I- ]/ c5 Ial.Rotate bq1, a1 ( d! w1 A% S7 |5 q; D2 i
al.Rotate3D bq1, bq4, a3 : A8 A2 [9 y9 j/ f1 }' a
Dim explodedobjects As Variant
$ [, m K/ ^+ z# k) z9 o rexplodedobjects = al.Explode
( U; A; m- n8 [( R2 g% p/ g9 K' C( kal.Delete ! X. k H: u+ \. d- X6 M
Dim i As Integer
8 n C# X/ E3 Z1 g; NDim kind As String
" K) E9 n1 \' ], M UDim parabolaobject As AcadSpline
3 J2 I% Q9 [! kFor i = 0 To UBound(explodedobjects) , \ I! H: a3 f, g! C3 W2 E
kind = explodedobjects(i).ObjectName : s" K$ X* D: R' B: V! S
If kind = "AcDbLine" Then 2 b0 G3 O- P# R3 q$ f
explodedobjects(i).Delete ( ]5 [. j, ]7 W
Else
# X. n7 G% r2 k7 y Set parabolaobject = explodedobjects(i) # s7 W+ |/ @! w& \1 _
End If . _9 B. H- _9 e6 P) C8 I
Next
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! f2 |2 r" z, D0 r'旋转抛物线 , b& U* O0 [6 q0 ]
ThisDrawing.SendCommand "rotate" & vbCr & "(Handent """ & parabolaobject.Handle & """)" & vbCr & "" & vbCr & bq1(0) & "," & bq1(1) & vbCr % Q( e( L, g o! c2 Q+ i/ b% o
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End Sub! R& g: T$ J$ `$ p7 {9 ~
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楼主: hyj_9766
发表于 2009-3-29 19:47:49
要活到老学到老,所以我们年轻人更应该抓紧学习了，
