Pixel buffer or pBuffer is a feature in OpenGL and OpenGL ES platform interfaces which allows for off-screen rendering. It is specified as an extension to WGL API, and a core feature of GLX & EGL.
When using pBuffers, a user can bind an OpenGL context to offscreen surfaces, effectively allowing for off-screen rendering to a default framebuffer, allocated by OpenGL itself.
The pBuffer functionality has been superseded by the usage of FBOs (Framebuffer Objects). However, pBuffers can be still used with modern OpenGL drivers.
pBuffers should not be confused with Pixel buffer objects (also named PBOs), which are non-renderable buffers containing raw pixel data.
A framebuffer is a portion of random-access memory (RAM) containing a bitmap that drives a video display. It is a memory buffer containing data representing all the pixels in a complete video frame. Modern video cards contain framebuffer circuitry in their cores. This circuitry converts an in-memory bitmap into a video signal that can be displayed on a computer monitor.
In computing, a windowing system is software that manages separately different parts of display screens. It is a type of graphical user interface (GUI) which implements the WIMP paradigm for a user interface.
Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a character set; at the same time, contrasted to all points addressable (APA) mode or other kinds of computer graphics modes.
GLX is an extension to the X Window System core protocol providing an interface between OpenGL and the X Window System as well as extensions to OpenGL itself. It enables programs wishing to use OpenGL to do so within a window provided by the X Window System. GLX distinguishes two "states": indirect state and direct state.
The X video extension, often abbreviated as XVideo or Xv, is a video output mechanism for the X Window System. The protocol was designed by David Carver; the specification for version 2 of the protocol was written in July 1991. It is mainly used today to resize video content in the video controller hardware in order to enlarge a given video or to watch it in full screen mode. Without XVideo, X would have to do this scaling on the main CPU. That requires a considerable amount of processing power, which could slow down or degrade the video stream; video controllers are specifically designed for this kind of computation, so can do it much more cheaply. Similarly, the X video extension can have the video controller perform color space conversions, and change the contrast, brightness, and hue of a displayed video stream.
In computer graphics, a shader is a type of computer program originally used for shading in 3D scenes. They now perform a variety of specialized functions in various fields within the category of computer graphics special effects, or else do video post-processing unrelated to shading, or even perform functions unrelated to graphics.
The Direct Rendering Infrastructure (DRI) is a framework for allowing direct access to graphics hardware under the X Window System in a safe, efficient way. The main use of DRI is to provide hardware acceleration for the Mesa implementation of OpenGL. DRI has also been adapted to provide OpenGL acceleration on a framebuffer console without a display server running.
Xgl is an obsolete display server implementation supporting the X Window System protocol designed to take advantage of modern graphics cards via their OpenGL drivers, layered on top of OpenGL. It supports hardware acceleration of all X, OpenGL and XVideo applications and graphical effects by a compositing window manager such as Compiz or Beryl. The project was started by David Reveman of Novell and first released on January 2, 2006. It was removed from the X.org server in favor of AIGLX on June 12, 2008.
A display list is a series of graphics commands that define an output image. The image is created (rendered) by executing the commands to combine various primitives. This activity is most often performed by specialized display or processing hardware partly or completely independent of the system's CPU for the purpose of freeing the CPU from the overhead of maintaining the display, and may provide output features or speed beyond the CPU's capability.
Utah GLX was a project aimed at creating a fully free and open-source basic hardware-accelerated 3D renderer using the OpenGL rendering API on Linux kernel-based operating systems. Utah GLX predates Direct Rendering Infrastructure, which is what is used as of 2014.
Accelerated Indirect GLX ("AIGLX") is an open source project founded by Red Hat and the Fedora community, led by Kristian Høgsberg, to allow accelerated indirect GLX rendering capabilities to the X.Org Server and DRI drivers. This allows remote X clients to get fully hardware accelerated rendering over the GLX protocol; coincidentally, this development was required for OpenGL compositing window managers to function with hardware acceleration.
Core OpenGL, or CGL, is Apple Inc.'s Macintosh Quartz windowing system interface to the OS X implementation of the OpenGL specification. CGL is analogous to GLX, which is the X11 interface to OpenGL, as well as WGL, which is the Microsoft Windows interface to OpenGL.
VirtualGL is an open source program that redirects the 3D rendering commands from Unix and Linux OpenGL applications to 3D accelerator hardware in a dedicated server and displays the rendered output interactively to a thin client located elsewhere on the network.
MiniGLX is a specification for an application programming interface which facilitates OpenGL rendering on systems without windowing systems, e.g. Linux without an X Window System or embedded systems without a windowing system. The interface is a subset of the GLX interface, plus a minimal set of Xlib-like functions.
The frame buffer object architecture (FBO) is an extension to OpenGL for doing flexible off-screen rendering, including rendering to a texture. By capturing images that would normally be drawn to the screen, it can be used to implement a large variety of image filters, and post-processing effects. The FBO is analogous to the render targets model in DirectX. It is used in OpenGL for its efficiency and ease of use. The use of FBOs doesn't suffer from the overhead associated with OpenGL drawing context switching, and has largely superseded the pbuffer and other methods involving context switches.
Java Binding for the OpenGL API is a JSR API specification for the Java Platform, Standard Edition which allows to use OpenGL on the Java. There is also Java Binding for the OpenGL ES API for the Java Platform, Micro Edition.
Direct Graphics Access is a plug-in for the X display servers that allows client programs direct access to the frame buffer.
WGL or Wiggle is an API between OpenGL and the windowing system interface of Windows. WGL is analogous to EGL, which is an interface between rendering APIs such as OpenCL, OpenGL, OpenGL ES or OpenVG and the native platform, as well as to CGL, which is the OS X interface to OpenGL.
EGL is an interface between Khronos rendering APIs and the underlying native platform windowing system. EGL handles graphics context management, surface/buffer binding, rendering synchronization, and enables "high-performance, accelerated, mixed-mode 2D and 3D rendering using other Khronos APIs." EGL is managed by the non-profit technology consortium Khronos Group.
This is a glossary of terms relating to computer graphics.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
