Polyline curves provide a greater range of editing tools that the other curves entities. Polyline curves are edited in exactly the same way as other curves and the BSpline Curve example provides a good guide to creating, editing, deleting and adding points to curve data.
Breaking a Polyline Curve into Two Polyline Curves
The sequence of points can often become corrupted and connected together in the wrong way. Breaking a curve at a control point allows the curve to be split up more curves and, if necessary, joined back together in a different order. Polyline curves are broken into two by selecting a single control point and choosing Break from the Right-Click menu, (Right-Click -> Polyline -> Break…).
Joining Polyline Curves Together
Sometimes data at individual longitudinal section locations consist of more than one curve. Two polyline curves can be joined together by selecting both curves and from the Right-Click menu choose Weld Polylines, (Right-Click -> Multiple Selection -> Weld Polylines). If more than two polyline curves are selected, all of the polylines can be welded together by consecutively joining the closest pair of end points, (Right-Click -> Multiple Selection -> Weld Multiple Polylines). Furthermore, a tolerance can be used to join only those curves with end points close to others, (Right-Click -> Multiple Selection -> Weld Multiple Polylines with tolerance). Sometimes a section curve may consist of a number of closed loops which need to be joined together to form a single section, for example to include the bulbous bow or propeller shaft. In this case, the Bridge polyline option can be used to connect two polyline curves at their closest approach, (Right-Click -> Multiple Selection -> Bridge Polylines).
Slicing Polylines using Planes
Section data can often contain more information that required, for example, only the port side of the hull may be required meaning that it may be necessary to strip away the starboard side. The slice function can be used to split polyline data based on an intersecting plane allowing the unnecessary data to be deleted. Grouped polyline data can also be sliced and become separate polyline groups.
Setting the start point
Certain analysis tools require the starting point of each polyline within the section data to be located at particular positions such as the deck or the keel. There is an option on the right click menu to allow this to be set for individual polyline curve, (Right-Click -> Polyline -> Set Point as First), which shifts the order of the polyline points until the select coordinate is at the start of the curve. The order of the points can also be reverse using Right-Click -> Polyline -> Reverse Points Order.