arc3P arcBulge arcTan arcToBezier bezier4P bezierIntersectionWithLine bezierIsStraight bezierPointDistantFromPoint bezierPointLengthFromStart bezierTanget bsplinesToBeziers crossLineCircle crossTwoCircles cubicSplines cubicSplineToBezier ellipse90ToBezier ellipseToBezier fitBezier FitCubicCallback fitCubicSpline fitCurve fitCurve2 fitCurve3 fitCurve4 gaussJordan lengthOfBezier PtCallback quadBezierToCubic roundRectToBeziers SplineFlags splitBezier triEquations

bezierPointLengthFromStart() float mgcurv::bezierPointLengthFromStart ( const Point2d *  pts, float  len  ) static 返回三次贝塞尔曲线段从起点开始的指定弧长处的点参数，范围为[0,1]