Graphics Reference
In-Depth Information
“side” vector
(
V
w
)
Rotation of the camera
with respect to the
camera “side” vector
Axis of rotation:
same direction as
V
w
located at camera Look At
Current
Camera Position
θ
x
“side” vector
(
V
w
)
Figure 15.5.
Up/down camera rotation.
Current
Camera Position
“Up” direction
of the world
θ
y
Rotation of the camera
with respect to the
“Up” direction
Figure 15.6.
Left/right camera rotation.
θ
y
and vertically by
θ
x
. We refer to horizontal rotation as
sub-y
because the rotation is defined with
respect to the up orientation, or the
y
-axis. Similarly, the
x
of
Let's assume that the camera is rotated horizontally by
θ
x
signifies the axis
of rotation. The camera orbiting rotations can be described as
R
v
w
R
y
M
or
=
(
θ
x
)
(
θ
y
)
,
(15.2)
where
R
is the rotation operator, and the superscripts
v
w
and
y
represent the
V
w
and
y
axes of rotation. To properly support camera tumbling, for every
θ
x
and
θ
y
user input, we need to compute the new camera position
p
new
e
:
p
new
e
=
p
e
M
or
(15.3)
p
e
R
v
w
R
y
=
(
θ
x
)
(
θ
y
)
.
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