- Start with 3D scene, but eventually project to 2D scene
- 2D scene is infinite plane. Device has a finite visible
rectangle.

What do we do? - Answer: map rectangular region of 2D device scene to device.
**Window:**- rectangular region of interest in scene.
**Viewport:**- rectangular region on device.

Usually, both rectangles are aligned with the coordinate axes.

\

- Window point maps to
viewport point .
Window has corners and ;

Viewport has corners and .Length and height of the window are and ,

Length and heigth of the viewport are and . - Proportionally map each of the coordinates according to:
- To map to :
and similarily for .

- If the image will be distorted.

These quantities are called the**aspect ratios**of the window and viewport.

*
Readings: Hearn and Baker: Section 6-3.
Red book: 5.5.
White book: 5.4,
Blinn: 16.
*

*
Intuitively, the window-to-viewport formula can be read as:
*

- Convert to a distance from the window corner.
- Scale this
*w*distance to get a*v*distance. - Add to viewport corner to get .

CS488/688: Introduction to Interactive Computer Graphics

University of Waterloo

Computer Graphics Lab