Chapter 1. Understanding Flash3D

Flash programmers have always enjoyed a freedom of expression unparalleled by other programming platforms. And with the release of CS4, Adobe has propelled that freedom of expression into the 3rd dimension.

But 3D didn't start with AS3. Flash developers were experimenting with 3D long before. And applications like Papervision3D formalized these endeavors into a robust object-oriented class structure. The acceptance and popularity of Papervision3D has become a driver of change in the Flash developer community. But underneath the 300 classes that make up Papervision3D still beats the original algorithms used by the early developers of Flash 3D.

Understanding how to create 3D in Flash is essential to fully grasping Papervision3D and applications like it. As you learn how 3D engines were originally constructed, you'll gain both an insight into Papervision3D's core architecture and an appreciation of its robust structure. Its complexity will fade into a set of fundamental 3D algorithms.

Papervision3D, at its core, is a perspective projection engine, where projection simply means transforming a 3D "object" space into 2D Flash x and y screen space. And surprisingly, the whole process hinges on one equation: a perspective scaling equation derived from Thales Theorem:

T = scale = focal length/(focal length + z)

In the equation above, T is the perspective scale, and z is the distance from the projection plane. The focal length (or calculated "screen" location) ...

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