CHAPTER 4
326
Graphics
Patch B
f
B
= 1
2
1
c
1
5
c
2
4
3
When
f
B
= 0, start a new patch.
6
8
3
c
3
7
2
c
1
1
4
c
2
Patch B
f
B
= 2
9
3
4
c
2
Patch A
12
2
1
c
1
3
c
2
4
2
11
10
c
4
c
1
1
Patch B
f
B
= 3
FIGURE 4.23
Edge connections in a Coons patch mesh
If the shading dictionary contains a
Function
entry, the color data for each corner
of a patch must be specified by a single parametric value
t
rather than by
n
sepa-
rate color components
c
1
…
c
n
. All linear interpolation within the mesh is done
using the
t
values. After interpolation, the results are passed to the function(s)
specified in the
Function
entry to determine the color at each point.