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AspEdit manual      Adding / subtracting shapes

Purpose

It can be useful to be able to add shapes together or to subtract a shape from another shape.
Examples:

General rules

Adding / subtracting a shape

  1. In the Area dialog box, press the add or insert button.  Use Insert only to insert before another shape.
  2. The Add element dialog box will open.
  3. Select "Shape", the Add shape dialog box will open.
  4. Select the desired shape, specify add or subtract.
  1. In the Area dialog box, press the add or insert button.  Use Insert only to insert before another shape.
  2. The Add fix dialog box will open.
  3. Press the "Add shape" button.
  4. Select the desired shape, specify add or subtract.

Adding or subtracting?

In most geographical software, shapes are turning clockwise as standard. This means that when viewed from the center, the points of the shape are sequenced clockwise.  If both the source shape and the shape from which to insert a segment are clockwise, adding and subtracting will be in the logical way .
However, if one shape is counterclockwise, adding / subtracted will be inverted.
In any case, check the results on the map display.  If the result is not as expected, invert the selection.

Modifying an added / subtracted shape line

In the list of the Area dialog box, double-click on the line defining the shape operation, the Add shape dialog box will open for the selected segment

Exporting

Any area that contains an added / subtracted shape will be expanded.  This means that all circles will be defined by points, rather than the OpenAir DC / DB records.