Game Development Reference
potential problems that happen when we let the camera get ''inside'' the geo-
metry. We want it to look through the back face of the wall to show us the player,
but the camera can also see through the back face of the floor above, showing us
the lower half of the figure on the second floor. The field of view has extended past
the corner of the ceiling and the wall, giving a partial view of the second floor. The
front face of the ceiling still blocks the rest of the second floor. The problematic
corner configuration seen in the side view of the wall and ceiling also shows up in
top-down views when one wall meets another wall. When walls meet, a camera
pushed inside the wall sees sideways past the walls of the current room.
The thick exterior wall makes this point of view possible. Because the first-floor
ceiling does not extend into the wall, its front face no longer prevents us from
seeing part of the upstairs. Extending the ceiling into the wall has two drawbacks.
The first is that it adds triangles that will rarely be seen, making work for our
artists and for our graphics pipeline for very little gain. The second is that if we
put our back to the other side of the wall, the camera would again go into the
wall; we would see the extended ceiling, and there is not supposed to be a ceiling
there! Note that on the left side of the wall, the view is open to the sky; this is an
exterior wall. This thick wall creates problems!
As shown in Figure 9.3, a thin wall presents problems, too. Figure 9.3 makes it
clear that we cannot let the camera punch through walls from the inside heading
Thin walls present their own camera problems.