Coordinate Systems	Coordinate Systems	Rect Objects

Point Objects

Point objects represent 2D points or vectors--depending on how you interpret them; their internal representation is identical.

While such points could be represented by Python tuples, this special object type requires less memory and overloads some arithmetic operators. A point object is represented by two C `float' numbers, one for each cartesian coordinate.

Point objects are immutable.

Constructors

There are two constructor functions:

Point(x, y)

Point(sequence)

Return a point object with the coordinates x and y. If called with one argument, the argument must be a sequence of two numbers. This form is called a PointSpec

Polar(r, phi)

Polar(phi)

Return a point object for the polar coordinates r and phi. If r is omitted, it defaults to 1.0.

Attributes

A point object has two (read only) attributes:

x

The X-coordinate of the point as a python float

y

The Y-coordinate of the point as a python float

Methods

A point object has these methods:

normalized()

Return a unit vector pointing in the same direction. If the point's length is 0, raise a ZeroDivisionError.

polar()

Return a tuple (r, phi) containing the polar coordinates of the point. phi is in the range -pi to pi. If r is 0, so is phi.

Operators

Point objects implement both the number and the sequence protocol for Python objects. This allows the following operations:

Number Protocol

+P

The same as P.

-P

The negated vector P. The same as

Point(-P.x, -P.y)

P1 + P2

The sum of the vectors P1 and P2. The same as

Point(P1.x + P2.x, P1.y + P2.y)

P1 - P2

The difference of the vectors P1 and P2. The same as

Point(P1.x - P2.x, P1.y - P2.y)

P1 * P2

The dot product of the vectors P1 and P2. The same as

P1.x * P2.x + P1.y * P2.y

NUMBER * P

P * NUMBER

The same as

Point(NUMBER * P.x, NUMBER * P.y)

P / NUMBER