iPhone Game Development

Graphics Engine

The graphics engine is in charge of visual output. This includes drawing graphical user interface (GUI) objects for the player to interact with, animating 2D sprites or 3D models, and rendering backgrounds and special effects.

Although the techniques used to render 2D and 3D graphics may be different, they evolve from the same set of graphics tasks. These include texturing and animation, in increasing order of complexity.

Texturing

Texturing is central to the display of graphics. In 2D, a flat image is displayed pixel by pixel to the screen, while in 3D, a collection of triangles (also called a mesh) undergoes some mathematical magic to produce a flat image, which is then also displayed on the screen. From there on, everything else gets more complicated.

Pixels, textures, and images

When drawing to the screen, the basic unit of measurement is a pixel. Each pixel can be broken into Red, Green, and Blue color values, along with an Alpha value for transparency that we’ll discuss shortly.

A texture is a collection of data about how to render a group of pixels. It contains color data for each pixel to be drawn.

An image is a high-level concept and is not directly related to a particular set of pixels or textures. When a human sees a group of pixels, her brain puts them together to form an image; e.g., if the pixels are in the right order, she might see an image of a giraffe.

It is important to keep these concepts separate. A texture might contain pixels that form the image of ...