Preliminaries - Real-Time Rendering: Computer Graphics with Control Engineering - page 5

2 Preliminaries

2.1 FUNDAMENTALS OF REAL-TIME 3D RENDERING
In real-time computer graphics, 3D rendering refers to the process of generating a
sequence of images that produces not just the animated effect of motion and change
but the visual cue of depth for objects in the imagery given an external input or stimu-
lus to the system. In typical applications, the goal is to provide visual feedback to the
user when there is interaction via the human-computer interface. The speed at which
each image, known as a frame, of the animation sequence is generated defines the
performance of the system.
Because speed of rendering every image is crucial in real-time rendering, both the
computer hardware and software have to work together in the most optimal way so
that the best possible image quality can be achieved in tandem with an acceptable
frame rate (a metric that measures the number of frames that can be generated in one
second). Over many years of research and development, the real-time 3D rendering
process has taken leaps and bounds in terms of the image quality that is produced in
various real-world applications such as computer games, training simulators and 3D
product demonstrations. This involves an intricate process that spans the preparation
of 3D content in elaborate modelling tools to processing combinations of rendering
algorithms with myriad configurations of parameters for the final output which is the
image to be shown eventually on the display device. Modern computers have dedicated
hardware to handle computer graphics rendering. This hardware provides acceleration
to computer graphics rendering routines so that the computer's central processor unit
(CPU) can focus on other non-computer-graphics-related and auxiliary tasks. In gen-
eral, real-time or interactive 3D rendering applications are supported by an abstraction
layer that communicates with the hardware. This layer is commonly known as the
3D rendering Application Programming Interface (API) and it is fully responsible for
pushing rendering commands to the hardware and managing the render state machine.

2.1.1 P olygon -B ased R endeRing
Figure 2.1 shows the multi-stage 3D real-time rendering pipeline. The transforma-
tion of inputs to the final visible pixels on a display device may be described system-
atically via the following steps.

• Creation in Local 3D Model Coordinate System

• Each object is created individually in its own 3D coordinate system.

• Objects may be represented in a variety of geometry formats (triangles,

rectangles, strips of polygons, etc.). Essentially, every polygon in a 3D
space consists of points known as vertices.

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