Page 97 - DCAP504_Computer Graphics

Computer Graphics

Two-dimensional computer graphics generally do not involve the need for any kind of
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three-dimensional internal representation of objects or characteristics in the computer.
However, some 2-D software employs 3-D techniques and ideas.

This unit discusses the concept of window and viewport and how they are mapped. We will also
discuss the different stages involved in the graphic pipeline. The panning and zooming concepts will
also be discussed in this unit.
7.1 Concept of Window and Viewport
The region of the scene or an object bounded by a rectangular area is known as a window. A window
simply means the frame outlines that define the part of a scene or object that is visible from a particular
position at a particular time.
The zone of the monitor screen within which a selected object is viewed is known as a viewport. The
zone is termed as viewport since it defines the area of the screen which can be viewed. The viewport is
generally seen as a rectangular area of the monitor screen in which the selected view is seen.

A window or viewport can be of any shape. However, the analysis for shapes other
than a rectangular area is complex. The overall method of analysis for all shapes will be
similar to the method of analysis followed for rectangles.

Window Definitions
There are few ways of defining a window. Firstly, a window should be described in any length
dimension, both horizontally and vertically.

Feet, meters and miles

As a common practice, the corners of a window are defined with reference to the world coordinate
origin. The dimensions are set into the computer as (x, y) data and subsequently changes will be applied
to the computer model.

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