Game Development Reference
In-Depth Information
Figure 2.2
More polygons means
more places to bend. This allows for
more rounded forms, but it requires a
bigger data set.
constructing forms of assembling polygons. Some methods are derived from
curves; others work along the line of creating polygons directly. But at the end
of the process, all the methods' results are turned into triangles by a process
called
tessellation
, so that the engine can see them and the video card can
draw them.
Rendering
This drawing of polygons and the textures and lighting associated with them
is called
rendering
. There are two kinds of rendering: software and hardware
rendering. Software rendering is what commonly is used in television and
film projects. The scene is built within a 3D application including lights and
textures, and then the CPU is engaged to draw the complex interaction of the
objects, colors, and lights in the scene. Because the results are displayed later
(not in real time), if it takes a second for a frame to be rendered, or a minute,
or even an hour per frame, this is acceptable. The sequential stills that are
the output of this process are put together via a video editing package, and
watched as a moving image.
Hardware rendering is much different. Games are in this category because
the video card renders the polygons within the digital space to represent
3D space. The hardware draws what is on the screen (including all the objects,
textures, and light) and needs to do so at many times per second. Generally,
if players are getting much below 30 frames per second, they notice the
choppiness of the game.
So how does a computer draw 30 frames per second of one project, but one
frame every 30 minutes of another? The answer is simply the size of the data
set and the hardware dedicated to handle that set. For projects that will not
be rendered in real time, the amount of data can be much higher. The number
of polygons can be much more, the size and number of textures bigger, and
the complex calculations of light more sophisticated. In real-time situations
(hardware rendering, with dedicated hardware chugging away on this data
set), the amount of data the video card deals with is much, much smaller.
