CmpRegion

A combination of two regions within a single Frame

Description:

A CmpRegion is a Region which allows two component Regions (of any class) to be combined to form a more complex Region. This combination may be performed a boolean AND, OR or XOR (exclusive OR) operator. If the AND operator is used, then a position is inside the CmpRegion only if it is inside both of its two component Regions. If the OR operator is used, then a position is inside the CmpRegion if it is inside either (or both) of its two component Regions. If the XOR operator is used, then a position is inside the CmpRegion if it is inside one but not both of its two component Regions. Other operators can be formed by negating one or both component Regions before using them to construct a new CmpRegion.

The two component Region need not refer to the same coordinate Frame, but it must be possible for the astConvert function to determine a Mapping between them (an error will be reported otherwise when the CmpRegion is created). For instance, a CmpRegion may combine a Region defined within an ICRS SkyFrame with a Region defined within a Galactic SkyFrame. This is acceptable because the SkyFrame class knows how to convert between these two systems, and consequently the astConvert function will also be able to convert between them. In such cases, the second component Region will be mapped into the coordinate Frame of the first component Region, and the Frame represented by the CmpRegion as a whole will be the Frame of the first component Region.

Since a CmpRegion is itself a Region, it can be used as a component in forming further CmpRegions. Regions of arbitrary complexity may be built from simple individual Regions in this way.

Constructor Function

astCmpRegion

Inheritance

The CmpRegion class inherits from the Region class.

Attributes

The CmpRegion class does not define any new attributes beyond those which are applicable to all Regions.

Functions

The CmpRegion class does not define any new functions beyond those which are applicable to all Regions.