API Reference > geometry-core > CartesianGeometry > Point2d > fractionOfProjectionToLine fractionOfProjectionToLine Method Return the fractional coordinate of the projection of this instance x,y onto the line from startPoint to endPoint. fractionOfProjectionToLine(startPoint: Point2d, endPoint: Point2d, defaultFraction?: number): number Parameter Type Description startPoint Point2d start point of line endPoint Point2d end point of line defaultFraction number fraction to return if startPoint and endPoint are equal. Returns - number Defined in geometry3d/Point2dVector2d.ts Line 264 Last Updated: 11 June, 2024