MENGZE 发表于 2013-5-4 00:28
版主,弱弱问下在CAD模型空间中椭圆形椎体怎么展开?求回复!!!
- ;;;=====================================================================
- ;;; 功能: 展开椭圆锥体。
- ;;; 输入: 椭圆锥底椭圆的长轴a,短轴b,椭圆锥的高h和分弧精度n
- ;;; 输出: 展开图的曲线的坐标点(可据此形成展开面)
- ;;;=====================================================================
- (defun ELL:ExpandCone (a b h n / Pts Ang D Param DivAng P0 P1 R0 R1 X Y)
- (setq DivAng (/ pi n 0.5)) ;等分角度
- (setq Param 0) ;开始参数为0
- (setq p0 (list a 0)) ;从椭圆最右边的点开始
- (setq r0 (distance '(0 0 0) (list a 0 h))) ;开始的锥顶最右边点的距离
- (setq Pts (list (list r0 0) '(0 0))) ;把最开始的两点加入到数据表
- (setq Ang 0) ;开始角度也为0
- (repeat n
- (setq Param (+ Param DivAng))
- (setq x (* a (cos Param))) ;椭圆上的x坐标
- (setq y (* b (sin Param))) ;椭圆上的y坐标
- (setq p1 (list x y)) ;点的坐标
- (setq r1 (distance '(0 0 0) (list x y h))) ;展开面的锥线长度
- (setq d (distance p0 p1)) ;椭圆上的上一点到这点的距离
- (setq Ang (+ Ang (car (TRI:CosinesLaw d r0 r1)))) ;坐标角度
- (setq Pts (cons (polar '(0 0) Ang r1) Pts)) ;得到了坐标,并把它加入到表中
- (setq p0 p1) ;用新的坐标位置替换旧位置
- (setq r0 r1) ;用新的锥线长度替换旧长度
- )
- (reverse Pts) ;逆转表,得到正序的数据
- )
- ;;; 测试椭圆锥的展开
- (defun c:ExpandCone(/ h N e d r c m a b l e o)
- (initget 1)
- (setq h (getdist "\n输入椭圆锥高: "))
- (initget 7)
- (setq N (getint "\n等分数:"))
- (prompt "\n选择椭圆:")
- (if (setq s (ssget ":S" '((0 . "ELLIPSE"))))
- (progn
- (setq e (ssname s 0))
- (setq d (entget e))
- (setq r (cdr (assoc 40 d)))
- (setq c (cdr (assoc 10 d)))
- (setq m (cdr (assoc 11 d)))
- (setq a (distance '(0 0 0) m))
- (setq b (* r a))
- (setq l (ELL:ExpandCone a b h n))
- (setq o (vlax-ename->vla-object (Ent:Make_LWPoly l T)))
- (vla-move o (vlax-3d-point '(0 0 0)) (vlax-3d-point c))
- (princ)
- )
- )
- )
- ;;;----------------------------------------------------;
- ;;; 功能: 根据三边求三个角(利用余弦定理) ;
- ;;; 输入: 构成三角形的三边a,b,c ;
- ;;; 输出: 返会三条边对应的三个角 ;
- ;;;----------------------------------------------------;
- (defun TRI:CosinesLaw (a b c / cc sc a1 a2)
- (if (TRI:IsTriangle a b c)
- (progn
- (setq a (float a)) ;为了防止整除
- (setq cc (/ (+ (* a a) (* (+ b c) (- b c))) (+ a a) b)) ;角C的余弦
- (setq sc (sqrt (* (- 1 cc) (1+ cc)))) ;角C的正弦
- (setq a1 (atan (* a sc) (- b (* a cc)))) ;角A
- (setq a2 (atan sc cc)) ;角C
- (list a1 (- pi a1 a2) a2) ;返回三个角度的列表
- )
- )
- )
- ;;;----------------------------------------------------;
- ;;;创建一个三维多段线 ;
- ;;;输入: 三维的点集 ;
- ;;;输出: 三维多段线实体 ;
- ;;;----------------------------------------------------;
- (defun Ent:Make_Poly (pts / e)
- (setq e (Entmake (list '(0 . "POLYLINE") '(70 . 9))))
- (foreach p pts
- (entmake (list '(0 . "VERTEX") '(70 . 32) (cons 10 p)))
- )
- (entmake '((0 . "SEQEND")))
- (entlast)
- )
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