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Closed - Should the boundary be considered to be inside the region?

Description:
This attribute controls whether points on the boundary of a Region are considered to be inside or outside the region. If the attribute value is non-zero (the default), points on the boundary are considered to be inside the region (that is, the Region is "closed"). However, if the attribute value is zero, points on the bounary are considered to be outside the region.
Type:
Integer (boolean).
Class Applicability:
Region
All Regions have this attribute.
PointList
The value of the Closed attribute is ignored by PointList regions. If the PointList region has not been negated, then it is always assumed to be closed. If the PointList region has been negated, then it is always assumed to be open. This is required since points have zero volume and therefore consist entirely of boundary.
CmpRegion
The default Closed value for a CmpRegion is the Closed value of its first component Region.
Stc
The default Closed value for an Stc is the Closed value of its encapsulated Region.


next up previous 264
Next: Colour(element) - Colour index for a Plot element
Up: AST Attribute Descriptions
Previous: ClipOp - Combine Plot clipping limits using a boolean OR?

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council