Pro OpenGL ES for iOS

218 CHAPTER 7: Well-Rendered Miscellany^

This demo has 24 such objects. Figure 7-6 shows the result.

Figure 7-6. Simple lens flare

Unfortunately, there is one big gotcha in the lens flare biz. What happens if your light

source goes behind something else? If it is a regular and known entity such as a round

sphere in the center of the scene, it is pretty easy to figure out. But if it is a random

object at a random place, it becomes much more difficult. Then what happens if the

source is only partially eclipsed? Reflections will then dim and flicker out only when the

entire object is hidden. The solution is left for you for the time being.

Stencils Reflective Surfaces

Another effect that is rapidly becoming a bit of a visual cliché, albeit still a cool one, is

that of a mirrored surface underneath part or all of the scene. We Mac-heads see that

every time we look at the Dock, for example, with the happy little icons dancing their jig-

of-joy up and down, in effect saying ‘‘Look here! look here!’’ in their little squeaky voices.

Underneath you will see a faint little reflection. It’s the same for many third-party apps,

of course, led by Apple’s own designs and examples. See Figure 7-7.