Page 17	Table of Contents	Index	Page 19
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E

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CHAPTER 3. REGIONS


Figure 3.1: Normalization of rectangular region sets.

=> region-intersection region1 region2 [Generic Function]
Returns a region that contains all points that are in both of the regions region1 and region2
(possibly with some points removed in order to satisfy the dimensionality rule). The result of
region-intersection has dimensionality that is the minimum dimensionality of region1 and
region2, or is +nowhere+. For example, the intersection of two areas is either another area or
+nowhere+; the intersection of two paths is either another path or +nowhere+; the intersection
of a path and an area produces the path clipped to stay inside of the area.

region-intersection will return either a simple region or a member of the class standard-region-intersection.

This function is permitted to capture its mutable inputs; the consequences of modifying those
objects are unspecified.

=> region-difference region1 region2 [Generic Function]
Returns a region that contains all points in the region region1 that are not in the region region2
(possibly plus additional boundary points to make the result closed). The result of region-
difference has the same dimensionality as region1, or is +nowhere+. For example, the difference
of an area and a path produces the same area; the difference of a path and an area produces the
path clipped to stay outside of the area.

region-difference will return either a simple region or a member of the class standard-region-difference.

This function is permitted to capture its mutable inputs; the consequences of modifying those

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Page 17	Table of Contents	Index	Page 19
	Chapters
	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 A, B, C, D, E