Page 12 | Table of Contents | Index | Page 14 |

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,
30A, B, C, D, E |

arcs, regions, and transformations. Both the graphics and windowing modules use the same set

of geometric objects and functions. In this section, we describe regions, points, and the basic

region classes. Transformations will be described in Chapter 5.

Most of these objects are described as if they are implemented using standard classes. However,

this need not be the case. In particular, they may be implemented using structure classes, and

some classes may exist only to name a place in the hierarchy|all members of such a class will

be instances of that class's subclasses. The most important concern is that these classes must

allow specializing generic functions.

The coordinate system in which the geometric objects reside is an abstract, continuous coordinate

system. This abstract coordinate system is converted into "real world" coordinates only during

operations such as rendering one of the objects on a display device.

Angles are measured in radians. Following standard conventions, when an angle is measured

relative to a given line, a positive angle indicates an angle counter-clockwise from the line in the

plane. When the angle from the positive

positive

be

Thus, the cartesian coordinate system with

right-handed. A coordinate system with

streams are left handed, but no such default exists for sheets in general.)

their boundaries, that is, they are closed. Regions have infinite resolution.

Page 12 | Table of Contents | Index | Page 14 |

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,
30A, B, C, D, E |