Using Pixmaps

Using Pixmaps

An OpenGL program can render to two kinds of drawables: windows and pixmaps. (Rendering to PBuffers is also possible if that extension is supported. See "The Pixel Buffer Extension".) A pixmap is an offscreen rendering area. On Silicon Graphics systems, pixmap rendering is not hardware accelerated.

Figure 4-2 : X Pixmaps and GLX Pixmaps In contrast to windows, where drawing has no effect if the window is not visible, a pixmap can be drawn to at any time since it resides in memory. Before the pixels in the pixmap become visible, they have to be copied into a visible window. The unaccelerated rendering for pixmap pixels has performance penalties.

This section explains how to create and use a pixmap and looks at some related issues:

"Creating and Using Pixmaps" provides basic information about working with pixmaps.
"Direct and Indirect Rendering" provides some background information; it is included here because rendering to pixmaps is always indirect.

Creating and Using Pixmaps
Direct and Indirect Rendering