Tips and Tricks: Offsett command options and variables
The offset command is probably one of the most used and loved commands by users. Well-deserved, I think, as the flexibility of this command makes it a very useful tool, and a helpful “accelerator” in your workflows.
Saying this, most users tend to use only a small part of the potential of this command. Here you can find information on a few more settings/options that are useful, often ignored, and that you can bring/adapt to your workflows.
Let’s start with the basics:
Offset: The command
The Offset command creates parallel shapes of Lines, 2D PolyLines, Circles, Arcs, Ellipses, Elliptical Arcs, Splines, Rays, and InfiniteLines. A copy of a selected entity is placed at a specified distance from the original entity. The original entity stays in position.
The offset depends on the type of drawing entity:
- Lines: Creates identical copies and moves in the direction and distance you specify.
- Circles, Arcs, and Ellipses: Creates and scales copies using the center of the entity as a base point for scaling. You can create concentric circles and arcs with radii smaller or larger than the original entities.
The Options
OK, nothing new until now. But the offset command options go beyond the “insert distance” that you want to separate the existing entity, to the new one that the command will create:
- Type _OFFSET in your command line (or in the Menu, click Modify > Offset).
- The command line prompts you to “Specify distance>”. Wait there! Take a closer look at the previous lines (of the command line):
As you can see, you have a line with “Default” (the default offset distance, and that you will change if you insert a new value), and a line with “Options”. So what are these options, and what do they do?
- Delete: Removes the original entity when the copy of the entity is placed.
- Distances: Creates multiple offsets. Select an entity to offset, and click on the side of the entity to offset. Specify the first distance and second point. Then you can specify additional offsets.
- Destination layer: Specifies whether the entity is to be copied on the active layer or source layer.
Quite nice, right? But let us go back a bit, to the default distance of offset.
The Variables
This value, as mentioned above, changes when you insert a new value. So here’s a tip for Premium users, that might want to run a LISP or a customization that includes offset. The offset default value is controlled by the variable SetOfstDst. This variable sets the default value for the offset command when prompting for the distance between the original and target entities.
A negative value offsets entities through a specified point and sets the through option as the default for the offset command. Again, the variable updates when you execute the offset command and specify a new offset distance to create parallel copies of entities.
But there’s more….
There is other variable “attached to this command, that can also be very helpful, and that is SETOFSTGAPMODE.
SETOFSTGAPMODE Controls how potential gaps between segments are treated when closed polylines are offset. For value:
- 0 - Fills the gaps by extending the polyline segments
- 1 - Fills the gaps with filleted arc segments (the radius of each arc segment is equal to the offset distance)
- 2 - Fills the gaps with chamfered line segments (the perpendicular distance to each chamfer is equal to the offset distance).
Intrigued? See below an example of a polyline offset, with the different values of SETOFSTGAPMODE:
As you can see from the results, this is a good example of what you can achieve by changing a single value of a variable, and that avoids having to perform several operations/commands, in order to obtain the same results.
