Construction Line (and Ray)

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Lines that extend to infinity in one or both directions, known as rays and construction lines, respectively, can be used as references for creating other objects. For example, you can use construction lines to find the center of a triangle, prepare multiple views of the same item, or create temporary intersections to use for object snaps.
Infinite lines do not change the total area of the drawing. Therefore, their infinite dimensions have no effect on zooming or viewpoints, and they are ignored by commands that display the drawing extents. You can move, rotate, and copy infinite lines just as you can move, rotate, and copy other objects. You may want to create infinite lines on a construction line layer that can be frozen or turned off before plotting.

A ray is a line in three-dimensional space that starts at a point you specify and extends to infinity. Unlike construction lines, which extend in two directions, rays extend in only one direction. Using rays instead of construction lines can help reduce visual clutter. Like construction lines, rays are ignored by commands that display the drawing extents.

To add construction lines and rays into a drawing use following functions:

Function	Meaning
lcBlockAddXline	By base point and a direction angle
lcBlockAddXline2P	By base point and second point

A construction line has properties and functions derived from base class and the following specific properties:

Property	Type	Access	Meaning
LC_PROP_ENT_...    Base class properties
LC_PROP_XLINE_X0	float	RW	Base point X
LC_PROP_XLINE_Y0	float	RW	Base point Y
LC_PROP_XLINE_ANG	float	RW	Direction angle
LC_PROP_XLINE_DIRX	float	R	Direction vector X
LC_PROP_XLINE_DIRY	float	R	Direction vector Y
LC_PROP_XLINE_RAY	bool	RW	Ray mode

Type specific functions:

Function	Meaning
lcXlinePutDir	Sets a direction of a construction line

Grips

0 - base point
1 - rotation


See also

  Retrieve objects