Page 26	Table of Contents	Index	Page 28
	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

Returns true if object is an ellipse, otherwise returns false.

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

=> make-ellipse center-point radius-1-dx radius-1-dy radius-2-dx radius-2-dy &key start-angle end-
angle [Function]
=> make-ellipse* center-x center-y radius-1-dx radius-1-dy radius-2-dx radius-2-dy &key start-
angle end-angle [Function]
Returns an object of class standard-ellipse. The center of the ellipse is at the point center-
point (or the position (center-x,center-y)).

Two vectors, (radius-1-dx,radius-1-dy) and (radius-2-dx,radius-2-dy) specify the bounding par-
allelogram of the ellipse as explained above. All of the radii are real numbers. If the two vectors
are collinear, the ellipse is not well-defined and the ellipse-not-well-defined error will be
signalled. The special case of an ellipse with its axes aligned with the coordinate axes can be
obtained by setting both radius-1-dy and radius-2-dx to 0.

If start-angle or end-angle are supplied, the ellipse is the "pie slice" area swept out by a line
from the center of the ellipse to a point on the boundary as the boundary point moves from
the angle start-angle to end-angle. Angles are measured counter-clockwise with respect to the
positive x axis. If end-angle is supplied, the default for start-angle is 0; if start-angle is supplied,
the default for end-angle is 2; if neither is supplied then the region is a full ellipse and the
angles are meaningless.

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

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

=> elliptical-arc-p object [Function]
Returns true if object is an elliptical arc, otherwise returns false.

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

=> make-elliptical-arc center-point radius-1-dx radius-1-dy radius-2-dx radius-2-dy &key start-
angle end-angle [Function]

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Page 26	Table of Contents	Index	Page 28
	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