Introduction to OpenGL

As a software interface for graphics hardware, the main purpose of OpenGL is to render two- and three-dimensional objects into a framebuffer. These objects are described as sequences of vertices (that define geometric objects) or pixels (that define images). OpenGL performs several processes on this data to convert it to pixels to form the final desired image in the framebuffer.

The following topics present a global view of how OpenGL works:

• Primitives and Commands discusses points, line segments, and polygons as the basic units of drawing; and the processing of commands.
• OpenGL Graphic Control describes which graphic operations OpenGL controls and which it does not control.
• Execution Model discusses the client/server model for interpreting OpenGL commands.
• Basic OpenGL Operation gives a high-level description of how OpenGL processes data to produce a corresponding image in the framebuffer.