vlax-curve-get族函数中参数在各种曲线中的含义

1、关于vlax-curve-get族函数中参数在各种曲线中的含义标签：vlax-curve-get族函数包括如下一些函数：vlax-curve-get族函数，包括如下一些函数：vlax-curve-getPointAtDistvlax-curve-getPointAtParamvlax-curve-getDistAtPointvlax-curve-getDistAtParamvlax-curve-getParamAtPointvlax-curve-getParamAtDistvlax-curve-getStartParamvlax-curve-getendParamvlax-curve-getS

2、tartPointvlax-curve-getEndPointvlax-curve-getFirstDerivvlax-curve-getSecondDerivvlax-curve-getSecondDeriv等，这些函数的使用时均要用到曲线参数，要用好这些函数，必须要搞明白曲线参数的含义，下面我就曲线参数在各种曲线中的含义解释如下：直线中，参数值为点在直线上距离起点长度；直线起点参数值为0,终点参数值为直线的长园、Param在圆弧、园、椭圆中，参数值为圆心到曲线起点逆时针旋转到该点的弧度度值;椭圆起点参数值为0,终点参数值为2pi,圆弧起点参数对应圆弧DXF的50码值，终点参数对应圆弧DXF

3、的51码值.Param在polyline中，参数值为计算点在polyline顶点上的顺序位置值，该值整数为计算点在polyline上的顶点顺序，以0为计数起点，小数部分为计算点在该poly片段上的长度比率。Param在在Spline中，是以Spline的拟合点进行直线连线，参数表示在该直线上距起点的距离。起点参数值为0,终点参数值为直线连线的总长度。vlax-curve-getFirstDeriv函数是返回曲线在指定位置的一阶导数(在WCS中)，其实(vlax-curve-getFirstDerivobjparam)函数计算的值是曲线上在参数值为param点处的切线方向，该值是一个表'

4、(xyz),运用下列方法可计算出在参数param处的切线方向的角度值：(setqang(angle(setqpt(vlax-curve-getpointatparamobjparam)(mapcar'+pt(vlax-curve-getFirstDerivobjparam)。vlax-curve-getSecondDeriv函数计算的是曲线法线方向值，该值是一个表'(xyz),运用上述方法同样可计算法线角度。如果计算点处曲线是直线，则返回'(0.00.00.0)。明白了参数的含义后，就可以通过上述函数进行各种曲线计算了，下面给出一些具体的应用举例：判断点是否在曲线上gx

5、l-pointoncurveptcurve测试(gxl-ptoncurve(getpoint)(car(entsel);(vlax-curve-getClosestPointTo(car(entsel)(getpoint)curvept)0.00001)(defungxl-ptoncurve(ptcurve)(equalpt(vlax-curve-getClosestPointTo;ax:GetCurveLength返回曲线长度;|功能返回曲线长度语法(gxl-ax:GetCurveLengthcurve)直线、圆弧、圆、多段线、优化多段线、样条曲线等图元返回值曲线长度样例(gxl-ax:Ge

6、tCurveLength(car(entsel)I；;(defungxl-ax:GetCurveLength(curve/)(if(='ENAME(typecurve)(setqcurve(vlax-ename->vla-objectcurve)(vlax-curve-getDistAtParamcurve(vlax-curve-getEndParamcurve);(gxl-Ax:GetMidpointCurvecurve)计算曲线中点(defungxl-Ax:GetMidpointCurve(curve/d)(setqd(/(gxl-ax:GetCurveLengthcurve

7、)2)curved)(vlax-curve-getPointAtDist;checkarc判断多段线是否有圆弧（凸度/=0）的子段;|功能判断多段线是否有圆弧（凸度/=0）的子段语法(checkarcename)ename:图元名返回值T:有圆弧段nil:无圆弧段|;(defuncheckarc(ename)(setqobj(vlax-ename->vla-objectename)(setqplist(vlax-safearray->list(vlax-variant-value(vla-get-coordinatesobj)(setqn0bunil)(repeat(/(lengt

8、hplist)2)(if(/=(vla-getbulgeobjn)0)(setqbuT)(setqn(+n1)bu;coodsofsegbynum返回多段线第n子段的端点坐标;|功能返回多段线第n子段的端点坐标语法(coodsofsegbynumobjn)obj:图元名:代表子段位置的整数坐标列表|;(defuncoodsofsegbynum(objn/en)(vlax-curve-getPointAtParamobjn);coordsofsegbypick返回多义线所点击子段的端点坐标;(coordsofsegbypick(car(entsel)(getpoint);|功能返回多义线所点击子

9、段的端点坐标语法(coordsofsegbypickenamep)name:图元名返回值坐标列表I；;(coordsofsegbypick(car(setqe(entsel)(cadre)(defuncoordsofsegbypick(objp/ppn)(setqpp(vlax-curve-getclosestpointtoobj(transp10)n(fix(vlax-curve-getparamatpointobjpp)(coodsofsegbynumobjn)coords2ptsegbypick返回多义线所点击子段的两个端点坐标，起点为靠近选择点(p1p2);(coords2ptsegb

10、ypick(car(setqe(entsel)(cadre)(defuncoords2ptsegbypick(objp/ppnp1p2)(setqpp(vlax-curve-getclosestpointtoobj(transp10)n(fix(vlax-curve-getparamatpointobjpp)nn(numbersofsegobj)(setqp1(coodsofsegbynumobjn)(if(vlax-curve-isClosedobj)(progn(if(<nnn)(setqp2(coodsofsegbynumobj(1+n)(setqp2(coodsofsegbynu

11、mobj0)(if(<(distancepp1)(distancepp2)(listp2p1)(progn(if(<nnn)(setqp2(coodsofsegbynumobj(1+n)(setqp2(coodsofsegbynumobj(1-n)(if(<(distancepp1)(distancepp2)(listp1p2)(listp2p1);coordsClosesegbypick返回多义线靠近所点击子段的端点坐标;(coordsClosesegbypick(car(setqe(entsel)(cadre)(defuncoordsClosesegbypick(objp)(car(coords2ptsegbypickobjp);(vlax-curve-getparamatpoint(vlax-ename->vla-object(car(setqe(entsel)(vlax-curve-getclosestpointtoobj(trans(cadre)10)返回多段线第n点的坐标,n起始值为0(coodsofnumpointenamen)例如：(coodsofnumpoint(car(entsel)2)(defuncoodsofnumpoint(objn/plist)(vlax-