Graphics Reference
In-Depth Information
As T x T y T z T must satisfy both plane equations,
n 1 ·
t
=
d 1 and n 2 ·
t
=
d 2
Furthermore, as v and t are orthogonal,
v
·
t
=
0
These three vector equations can be combined and written as
d 1
d 2
0
a 1 b 1 c 1
a 2 b 2 c 2
a v b v c v
x T
y T
z T
=
·
and solved using Cramer's rule, where
d 1 b 1 c 1
d 2 b 2 c 2
0 b v c v
a 1 d 1 c 1
a 2 d 2 c 2
a v 0 c v
a 1 b 1 d 1
a 2 b 2 d 2
a v b v 0
x T =
y T =
z T =
DET
DET
DET
a 1 b 1 c 1
a 2 b 2 c 2
a v b v c v
DET
=
and
i j k
a 1 b 1 c 1
a 2 b 2 c 2
v
=
To illustrate this technique, let's consider a scenario whose outcome can be predicted as shown
in Fig. 6.27, where two planes intersect along the line p
=
t
+
v , where t
=
j and v
=
i .
The plane equations are
y
z
=
1
and y
+
z
=
1
Therefore,
n 1 =
j
k
and n 2 =
j
+
k
and
i j k
01
v
=
n 1 ×
n 2 =
1
01 1
=
2 i
01
1
01 1
20 0
DET
=
=
4
 
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