So how does an imaginary three-dimensional world come to be represented by two-dimensional images on a computer screen? Consider someone in a room, looking through a window at the world outside. What that person sees through the window is determined by a number of factors: where they are positioned in the room, the direction and orientation of their gaze, the field of view, the lighting conditions etc.
A 3D computer graphics system attempts to mimic this viewing process.
Figure 1 A 3D Graphics System mimics how we view the world through a window
A mathematical representation of an imaginary world is used to simulate the `real' world. A number of user defined parameters determine what is actually displayed on (or projected onto) the computer screen. These include the view position (sometimes referred to as the camera position), the view direction and orientation, the shape of the view volume, and the specified lighting conditions.
A 3D graphics simulation can be thought of as a three stage process. Firstly, an imaginary scene is described to the system in a language it understands. Then, a representation of what is currently `visible' in the world is projected onto the screen. Finally, the colour of each picture element, or pixel, on the screen is calculated.
Figure 2 3D Graphics Simulation Sequence
The process whereby a scene gets drawn (stages 2 and 3 above), given an arrangement of previously defined models, is known as rendering. A very powerful rendering engine lies at the heart of BRender.