ZWCAD offers many tools for working with closed shapes, making it easier to edit and clean up your drawings. This guide walks you through how to define regions, apply wipeouts, and create boundaries from closed areas for more convenient drafting experience.

Create Regions

Execute the REGION command to create a region from a closed 2D shape. Regions enable you to perform editing and design tasks like:

• Extract design information
• Hatch and color
• Perform Boolean operations such as union, subtraction, intersection, etc.

Constituent Objects

The object used to create a region must be a 2D closed area, like a circle, ellipse, closed polyline, etc. It can also be a closed combination of lines, polylines, arcs, and elliptical arcs, etc.

If the selected objects only intersect without fully connecting, they can't form a region.

In the left figure, the endpoints of two polylines are connected, forming a closed area. This can be made into a region.

In the right figure, the polylines intersect but don't fully connect. This cannot be used to create a region.

Boolean Operation

Boolean operations let you combine or edit regions in several ways:

· UNION: Combines multiple regions into one

· SUBTRACT: Removes the overlapping parts of one region from another

· INTERSECT: Keeps only the overlapping area of multiple regions

Create Wipeouts

Execute the WIPEOUT command to create a wipeout.

A wipeout is a special object that hides anything underneath it by covering it with the background color.

As shown in the figure, an object is hidden by a rectangular wipeout area.

The size and position of the wipeout shape determine what gets hidden. If you move the wipeout or drag its corners, the hidden area will update to match.

Wipeout Frame

The WIPEOUTFRAME system variable allows you to control whether the frame (outline) of a wipeout is shown on screen or plotted. When the values are:

• 0 — the frame is not displayed or plotted
• 1 — the frame is displayed and plotted
• 2 — the frame is displayed but not plotted

Create Polyline Boundary

Execute the BOUNDARY command to create a polyline or region from a closed area.

Often, a closed area is made up of multiple objects, which are hard to select or edit one by one. A polyline boundary makes it easier to copy, move, or modify.

As shown in the figure, you can run the BOUNDARY command and click inside the area to create a polyline boundary formed by the intersection of five circles.

Boundary Set

The boundary set limits which objects are considered when finding the boundary. To use one:

1. Create the boundary set by choosing the objects you want to include
2. Click inside the closed area you want to extract
3. The boundary will be generated only from the selected set, avoiding interference from other shapes.

Island Detection

An island is a closed area inside another closed area. Island detection allows you to choose whether to include these inner shapes when creating boundaries:

· Nested islands: Includes all inner closed areas 

· Outer only: Includes only the first closed area inside

· Ignore islands: Do not include any inner closed areas