Data Block Sequence

Data Block 001( x1, y1 )

- Start-point

Data Block 002( x2, y2 )

- Definition point

Data Block 002( x?, y? )

- End-point

A spline is a curve that connects a sequence of points with a curved line as "smooth" as possible, i.e. the connecting line has no sharp bends and a minimum deflection. The theory of splines covers several types of splines, basically differing in the way that "smoothness" is defined.

The most usual spline form in technical design is a "cubic spline", so this form is used here. Since the calculation effort for a plain cubic spline is enormous, the application uses an interpolation method that first calculates a short cubic spline for each point triple, resulting in two different curve segments for each point-to-point segment. The resulting curve is then calculated as the connection of those two curve segments.

If a spline is drawn with a non-solid line type, this line type has to be continued along the complete spline. A spline may contain up to 2000 data blocks in total.

A spline is by definition an "open" object, i.e. it has a non-closed outline and cannot be filled.

Attributes New in Version 2021.0

A spline may contain attribute data blocks (see MKI_BLOCK_ATTRIBUTE) of types "local", "outline", and "point". Their position in the list of data blocks must be as follows:

-	Outline attributes must be placed anywhere behind the first point. Any outline attribute after the first point data block belongs to the outline.

-	Point attributes must be placed behind the respective point. Any point attribute after point data block P and before the next point data block (or end of object) belongs to that point P.

-	Local attributes should be placed behind all other datablocks and attributes.

The total number of attributes of each type (local, outline, point) per respective element (entity, outline, and point) is limited to MKI_ATTRIBS_PER_OBJECT.

Interface Command Sequence

MKI_ObjectOpen, Type = MKI_OBJ_SPLINE

MKI_ObjectAddPoint, Type = MKI_DB_POINT_START

MKI_ObjectAddPoint, Type = MKI_DB_POINT_END

...

MKI_ObjectAddPoint, Type = MKI_DB_POINT_END

MKI_ObjectFastInsert