Graphics Reference
In-Depth Information
Again, to simply the mathematics, let's find out what happens at the point u
=
v
=
0.
To begin with,
P
u
=−
k
P
v
=
j
N
=
i
From Fig. 10.11, we see that
F
u
=
205
−
200
=
5
F
v
=
10
In calculating F
u and F
v, we ignore delta increments in u and v, as this can be
compensated for by introducing a scaling factor, which will also control the impact the bump
map has on
N
. Let this scaling factor be with an initial value of 1.
Modifying Eq. 10.9 with produces
210
−
200
=
N
N
⎛
⎝
⎞
⎠
F
u
P
v
F
v
P
u
×
−
×
N
=
N
+
(10.17)
N
P
v and
N
P
u:
Now let's calculate
N
×
×
ijk
100
010
P
v
=
N
×
=
k
ij k
10 0
00
P
u
=
N
×
=
j
−
1
Substituting all the above terms in Eq. (10.17), we obtain
N
=
i
+
5
k
−
10
j
and if
=
1,
N
=
i
−
10
j
+
5
k
If this is seen to be visually unacceptable, can be set to some suitable value. In fact, let's make
=
001 and then compute
N
again:
N
=
i
−
01
j
+
005
k
