A GM_LineSegment consists of two distinct DirectPositions (the startPoint and endPoint) joined by a straight line. Thus its interpolation attribute shall be "linear". The default GM_GenericCurve::parameterization = c(s) is:<br/>(L : Distance) = endParam - startParam<br/>c(s) = ControlPoint[1]+((s-startParam)/L)*(ControlPoint[2]-ControlPoint[1])<br/><br/>Any other point in the controlPoint array must fall on this line. The control points of a GM_LineSegment shall all lie on the straight line between its start point and end point. Between these two points, other positions may be interpolated linearly. <br/>NOTE The linear interpolation, given using a constructive parameter t, 0 £ t £ 1.0, where c(o) = c.startPoint() and c(1)=c.endPoint(), is:<br/> <br/>c(t) = t c(1)  + (1-t) c(0)<br/>