Flash 3D Applications: Putting It All Together - Flash 3D: Animation, Interactivity, and Games - page 394

space. Viewed from above, we have the situation illustrated by the left side of Figure
11.36. Everything is aligned, and no movement of the planes will give us what we want.

Vanishing Point

Vanishing Point

No Movement

Narrow Wider

Small range of motion
between layers

Greater range of motion
between layers

Figure 11.36 The vanishing point determines the layer range of motion.

We need to establish a vanishing point for the layers and then size the layers to be con-
sistent with the vanishing point as shown in the center and right side of Figure 11.36.
If the vanishing point is very far away, only a small amount of movement between the
layers is possible. As the vanishing point is brought in, a greater range of motion is
possible, but there must be a greater size difference between the individual layers.

In our case, the various layer images already reflect the scaling caused by perspective.
We need to change the layer size horizontally, but we do not have to make any changes
in size of the layer images. The marquees in the individual layers were increased in size
using the background layer as the baseline as shown in Figure 11.37.

The next thing to be determined is the amount each layer could move to be consistent
with the vanishing point. We know from our work with panoramas that the maximum
value for movement of the background is the background width divided by 2, and the
minimum value is the Stage width minus the maximum value.