Chapter 7 - Window system and platform integration

Abstract

This chapter describes the background of the aspects of windows systems embedding under the following headings: renderer and window state, address space and threads, anatomy of a window, off-screen rendering, rendering to texture maps, and direct and indirect rendering. OpenGL API is primarily concerned with accepting procedural scene descriptions and generating pixels corresponding to those descriptions. The final step of sending pixels to their target, such as a window on the screen, is left up to the embedding or platform layer. This layer defines the way the OpenGL renderer attaches or binds into the output device or devices. Here, the embeddings of three of the most popular windows systems are mentioned: the X Window System embedding called GLX; the embedding into the Win32 API used by Microsoft's Windows family of operating systems called WGL; and the embedding connecting Apple's Macintosh operating system called AGL. The OpenGL ES project also includes a more portable window system embedding layer called EGL.