
368 Chapter 6 Spatial Sorting
P
0
R
0
P
3
P
7
P
1P
2
R
1
P
6
P
5
R
2
P
8
P
4
R
0
R
1
P
0
P
1
P
2
P
3
P
7
P
8
R
2
P
5
P
6
P
4
Outside
(a) (b)
Figure 6.5
A configuration of three regions, nine portals, and an outside area. (a) The geometric
layout for the regions and portals. (b) The directed graph associated with it.
shows a specific configuration of regions and portals, including the directed graph
associated with it.
The portal P
0
is from the outside to inside the collection of regions. The portal
is displayed as if the door were closed. Once a player-character stands in front of the
door, a mouse click can open it. The character steps through, and the door closes
behind him (never to open again). The ...