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	Chapters
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CHAPTER 3. REGIONS

=> point-x point [Generic Function]
=> point-y point [Generic Function]
Returns the x or y coordinate of the point point, respectively. CLIM will supply default methods
for point-x and point-y on the protocol class point that are implemented by calling point-
position.

3.2.2 Polygons and Polylines

A polyline is a path that consists of one or more line segments joined consecutively at their
end-points.

Polylines that have the end-point of their last line segment coincident with the start-point of
their first line segment are called closed; this use of the term "closed" should not be confused
with closed sets of points.

A polygon is an area bounded by a closed polyline.

If the boundary of a polygon intersects itself, the odd-even winding-rule defines the polygon:
a point is inside the polygon if a ray from the point to infinity crosses the boundary an odd
number of times.

=> polyline [Protocol Class]
The protocol class that corresponds to a polyline. This is a subclass of path. If you want to
create a new class that behaves like a polyline, it should be a subclass of polyline. Subclasses
of polyline must obey the polyline protocol.

=> polylinep object [Function]
Returns true if object is a polyline, otherwise returns false.

=> standard-polyline [Class]
An instantiable class that implements a polyline. This is a subclass of polyline. This is the class
that make-polyline and make-polyline* instantiate. Members of this class are immutable.

=> make-polyline point-seq &key closed [Function]
=> make-polyline* coord-seq &key closed [Function]
Returns an object of class standard-polyline consisting of the segments connecting each of
the points in point-seq (or the points represented by the coordinate pairs in coord-seq). point-seq
is a sequence of points; coord-seq is a sequence of coordinate pairs, which are real numbers. It is
an error if coord-seq does not contain an even number of elements.

If closed is true, then the segment connecting the first point and the last point is included in the
polyline. The default for closed is false.

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

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Page 20	Table of Contents	Index	Page 22
	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