OTHER LINES

Yesterday we experimented with ‘Line’. Today we will learn about the other lines in the Line group. 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.

Rays
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.

Construction Lines
A construction line (xline) can be placed anywhere in three-dimensional space. You can specify its orientation in several ways. The default method for creating the line is the two-point method: you specify two points to define the orientation. The first point, the root, is the conceptual midpoint of the construction line, that is, the point snapped to by the Midpoint object snap.
You can also create construction lines in several other ways.
• Horizontal and Vertical. Create construction lines that pass through a point you specify and are parallel to the X or Y axis of the current UCS.
• Angle. Creates a construction line in one of two ways. Either you select a reference line and then specify the angle of the construction line from that line, or you create a construction line at a specific angle to the horizontal axis by specifying an angle and then a point through which the construction line should pass.
• Bisector. Creates a construction line that bisects an angle you specify. You specify the vertex and the lines that create the angle.
• Offset. Creates a construction line parallel to a baseline you specify. You specify the offset distance, select the baseline, and then indicate on which side of the baseline to locate the construction line.

Multiline
Multilines are composed of 1 to 16 parallel lines, called elements. When you draw a multiline, you can use the STANDARD style, which has two elements, or specify a style that you created previously. You can also change the justification and scale of the multiline before you draw it.

Multiline justification determines which side of the cursor that the multiline is drawn, or whether it is centered on the cursor.

Multiline scale controls the overall width of the multiline using the current units. Multiline scale does not affect linetype scale. If you change the multiline scale, you might need to make equivalent changes to the linetype scale to prevent dots or dashes from being disproportionately sized.
Create Multiline Styles
You can create named styles for multilines to control the number of elements and the properties of each element. The properties of multilines include
• The total number of elements and position of each element
• The offset distance for each element from the middle of the multiline
• The color and linetype of each element
• The visibility of the lines, called joints, that appears at each vertex
• The type of end caps that are used
• The background fill color of the multiline

You can add up to 16 elements to a multiline style. Elements with a positive offset appear on one side of the middle of the multiline; elements with a negative offset appear on the other side of the middle of the multiline.

Modify Multiline
Multiline objects are composed of 1 to 16 parallel lines, called elements. To modify multilines or their elements, you can use common editing commands, a multiline editing command, and multiline styles. Special multiline editing features are available with the MLEDITcommand including the following:
• Add or delete a vertex
• Control the visibility of corner joints
• Control the style of intersection with other multilines
• Open or close gaps in a multiline object

Add and Delete Multiline Vertices
You can add or delete any vertex in a multiline.

Edit Multiline Intersections
If you have two multilines in a drawing, you can control the way they intersect. Multilines can intersect in a cross or a T shape, and the crosses or T shapes can be closed, open, or merged.

Edit Multiline Styles
You can use MLSTYLE to edit multiline styles to change the properties of multiline elements or the end caps and background fill of subsequently created multilines.
Multiline styles control the number of line elements in a multiline and the color, linetype, lineweight, and offset of each element. You can also modify the display of joints, end caps, and background fill.

Multiline styles have the following limitations:
• You cannot edit the element and multiline properties of the STANDARD multiline style or any multiline style already used in the drawing.
• To edit an existing multiline style, you must do so before you draw any multilines in that style.

Note - If you use MLSTYLE to create a multiline style without saving it, and then select another style or create a new style, the first MLSTYLE properties are lost. To maintain the properties, save each multiline style to an MLN file before creating a new one. Use Common Editing Commands on Multilines

You can use most of the common editing commands on multilines except
• BREAK
• CHAMFER
• FILLET
• LENGTHEN
• OFFSET

To perform these operations, first use EXPLODE to replace the multiline object with separate line objects.

Note – If you trim or extend a multiline object, only the first boundary object encountered determines the shape of the end of the multiline. A multiline cannot have a complex boundary at its endpoint.

We will practice these types of lines in our assignment as and when appropriate. Tomorrow we will try to understand some viewing commands as we will need them to continue with our assignment.

Stay tuned…!