vlax-curve-get族函數(shù)中參數(shù)在各種曲線中的含義

1、關于vlax-curve-get族函數(shù)中參數(shù)在各種曲線中的含義標簽：vlax-curve-get族函數(shù)包括如下一些函數(shù)：vlax-curve-get族函數(shù)，包括如下一些函數(shù)：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，這些函數(shù)的使用時均要用到曲線參數(shù)，要用好這些函數(shù)，必須要搞明白曲線參數(shù)的含義，下面我就曲線參數(shù)在各種曲線中的含義解釋如下：直線中，參數(shù)值為點在直線上距離起點長度；直線起點參數(shù)值為0,終點參數(shù)值為直線的長園、Param在圓弧、園、橢圓中，參數(shù)值為圓心到曲線起點逆時針旋轉到該點的弧度度值;橢圓起點參數(shù)值為0,終點參數(shù)值為2pi,圓弧起點參數(shù)對應圓弧DXF的50碼值，終點參數(shù)對應圓弧DXF

3、的51碼值.Param在polyline中，參數(shù)值為計算點在polyline頂點上的順序位置值，該值整數(shù)為計算點在polyline上的頂點順序，以0為計數(shù)起點，小數(shù)部分為計算點在該poly片段上的長度比率。Param在在Spline中，是以Spline的擬合點進行直線連線，參數(shù)表示在該直線上距起點的距離。起點參數(shù)值為0,終點參數(shù)值為直線連線的總長度。vlax-curve-getFirstDeriv函數(shù)是返回曲線在指定位置的一階導數(shù)(在WCS中)，其實(vlax-curve-getFirstDerivobjparam)函數(shù)計算的值是曲線上在參數(shù)值為param點處的切線方向，該值是一個表'

4、(xyz),運用下列方法可計算出在參數(shù)param處的切線方向的角度值：(setqang(angle(setqpt(vlax-curve-getpointatparamobjparam)(mapcar'+pt(vlax-curve-getFirstDerivobjparam)。vlax-curve-getSecondDeriv函數(shù)計算的是曲線法線方向值，該值是一個表'(xyz),運用上述方法同樣可計算法線角度。如果計算點處曲線是直線，則返回'(0.00.00.0)。明白了參數(shù)的含義后，就可以通過上述函數(shù)進行各種曲線計算了，下面給出一些具體的應用舉例：判斷點是否在曲線上gx

5、l-pointoncurveptcurve測試(gxl-ptoncurve(getpoint)(car(entsel);(vlax-curve-getClosestPointTo(car(entsel)(getpoint)curvept)0.00001)(defungxl-ptoncurve(ptcurve)(equalpt(vlax-curve-getClosestPointTo;ax:GetCurveLength返回曲線長度;|功能返回曲線長度語法(gxl-ax:GetCurveLengthcurve)直線、圓弧、圓、多段線、優(yōu)化多段線、樣條曲線等圖元返回值曲線長度樣例(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)計算曲線中點(defungxl-Ax:GetMidpointCurve(curve/d)(setqd(/(gxl-ax:GetCurveLengthcurve

7、)2)curved)(vlax-curve-getPointAtDist;checkarc判斷多段線是否有圓?。ㄍ苟?=0）的子段;|功能判斷多段線是否有圓弧（凸度/=0）的子段語法(checkarcename)ename:圖元名返回值T:有圓弧段nil:無圓弧段|;(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返回多段線第n子段的端點坐標;|功能返回多段線第n子段的端點坐標語法(coodsofsegbynumobjn)obj:圖元名:代表子段位置的整數(shù)坐標列表|;(defuncoodsofsegbynum(objn/en)(vlax-curve-getPointAtParamobjn);coordsofsegbypick返回多義線所點擊子段的端點坐標;(coordsofsegbypick(car(entsel)(getpoint);|功能返回多義線所點擊子

9、段的端點坐標語法(coordsofsegbypickenamep)name:圖元名返回值坐標列表I；;(coordsofsegbypick(car(setqe(entsel)(cadre)(defuncoordsofsegbypick(objp/ppn)(setqpp(vlax-curve-getclosestpointtoobj(transp10)n(fix(vlax-curve-getparamatpointobjpp)(coodsofsegbynumobjn)coords2ptsegbypick返回多義線所點擊子段的兩個端點坐標，起點為靠近選擇點(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返回多義線靠近所點擊子段的端點坐標;(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)返回多段線第n點的坐標,n起始值為0(coodsofnumpointenamen)例如：(coodsofnumpoint(car(entsel)2)(defuncoodsofnumpoint(objn/plist)(vlax-