Graphics Reference
In-Depth Information
Fig. 11.8
The cube is rotated 90° about the axis intersecting vertices 4 and 6
The other two matrices are
⎡
⎤
100
1
010 0
001 0
000 1
−
⎣
⎦
T
=
−
t
x
,
0
,
0
⎡
⎤
1001
0100
0010
0001
⎣
⎦
T
t
x
,
0
,
0
=
.
Multiplying these matrices together creates
⎡
⎤
0011
0100
⎣
⎦
−
1001
0001
which when applied to the cube's coordinates produces
⎡
⎣
⎤
⎦
⎡
⎣
⎤
⎦
0011
0100
00001111
00110011
01010101
11111111
−
1001
0001
⎡
⎤
12121212
00110011
11110000
11111111
⎣
⎦
=
.
These coordinates are confirmed by Fig.
11.8
(a) and (b).
11.7 Frames of Reference
Chapter 10 explored various techniques for changing the coordinates of objects in
different frames of reference. Now that we have covered quaternions, and especially
