Often, a shadow is distorted to such an extent that Layer Styles do not work. In such cases, the shadow has to be generated directly from the casting object and modified by hand. In Figure 4.24, the tree's shadow, if it is to look realistic, has to bend sharply where it meets the background wall.
Figure 4.24. The tree casts a shadow that travels across the ground and up the wall.
To create this effect, the layer with the tree is duplicated. The Preserve Transparency option is turned on for the layer, and then it is filled with black. The black tree is then distorted (Edit>Transform>Distort). The distorted shape resembles the shadow traveling on the ground (Figure 4.25).
Figure 4.25. The shadow for the tree is distorted to represent the shadow on the ground.
A second layer with another black-filled tree is placed in position where the shadow falls on the wall (Figure 4.26). It is reduced in size to simulate the effect of distance. Things appear smaller as they get farther away from the viewer. In Figure 4.27, you see the smaller black tree clipped by the layer of the wall.
Figure 4.26. A duplicate layer with the tree shadow is reduced in size to simulate distance, and it's placed so that its top half overlaps the base of the wall.
Figure 4.27. The layer of the wall clips the duplicate layer with the tree shadow.
The layer for the shadow created in Figure 4.25 is placed behind the layer with the wall. As a result, the wall hides the part of the shadow that is to be replaced by the shadow against the wall in Figure 4.27. It takes two shadows to create the illusion of a single shadow being cast on to two surfaces.
In Figure 4.28, a new ingredient is thrown into the mixthe wall is angled with respect to the tree and light source. This creates the effect of a lengthened shadow. The diagram in Figure 4.29 demonstrates the physics at work here.
Figure 4.28. Because the wall is positioned at an angle from the light source, the tree's shadow is elongated.
Figure 4.29. This diagram shows what happens to a shadow when it hits a surface that is straight, as opposed to one that is at an angle.