ARBpbuffer

ARB_pbuffer is a set of OpenGL extensions that provides offscreen rendering surfaces known as pbuffers. A pbuffer is an offscreen rendering target that exists in video memory and does not require a visible window, allowing rendering operations to proceed in the background and the resulting image to be consumed as a texture or read back to memory. The extensions were created under the OpenGL Architecture Review Board (ARB) to support offscreen rendering across different window systems.

On Windows, the functionality is exposed by the WGL_ARB_pbuffer extension; on X11-based systems, it is exposed by GLX_ARB_pbuffer. These extensions define the procedures to create, manage, and destroy pbuffers, and to obtain a rendering context that can render into the pbuffer. They also provide mechanisms to bind the pbuffer as a texture, enabling render-to-texture workflows.

Typical usage involves selecting a suitable color and depth/stencil buffer configuration, creating a pbuffer object with the desired attributes, making a GL context current for that pbuffer, performing rendering, and then optionally binding the pbuffer to a texture for later use. After rendering, the pbuffer can be released or destroyed when no longer needed. Context sharing between pbuffers is supported in some implementations, facilitating resource sharing across multiple contexts.

ARB_pbuffer is largely superseded by modern framebuffer object (FBO) functionality introduced later in the OpenGL ecosystem, which provides a more flexible and widely supported offscreen rendering path. Nevertheless, pbuffers remain part of historical usage and may be encountered in legacy applications and drivers with limited FBO support.

See also: OpenGL, ARB extensions, WGL_ARB_pbuffer, GLX_ARB_pbuffer, ARB_framebuffer_object.