Rotating And/Or Elevating The Viewing Angle - Texas Instruments TI-89 Manual Book

Rotating and/or Elevating the Viewing Angle

How the Viewing
Angle Is Measured
Note: When eye =0 , the
z axis is vertical on the
screen. When eye =90 ,
the z axis is rotated 90¡
counterclockwise and is
horizontal.
Effect of Changing
eyeq
Note: This example
increments eyeq by 30 .
162 Chapter 10: 3D Graphing
In 3D graphing mode, the eyeq and eyef Window variables let
you set viewing angles that determine your line of sight. The
eye Window variable lets you rotate the graph around that
line of sight.
The viewing angle has three components:
¦
eyeq — angle in degrees from the
positive x axis.
¦
eyef — angle in degrees from the
positive z axis.
¦
— angle in degrees by which the
eye
graph is rotated counterclockwise
around the line of sight set by
and .
eyef
In the Window Editor ( ¥ $ ),
always enter
eyeq, eyef, and eye
degrees, regardless of the current angle
mode.
Do not enter a ¡ symbol. For example,
type 20, 70, and 0, not 20¡, 70¡, and 0¡.
The view on the Graph screen is always oriented along the viewing
angle. From this point of view, you can change
viewing angle around the z axis.
y - y
3 3
z1(x,y) = (x
X
eyeq
in
x) / 390 In this example, eyef = 70
eyeq = 20
eyeq = 50
eyeq = 80
Z
eyef
eye
Y
eyeq
to rotate the
eyeq