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The '''frame buffer object''' architecture (FBO) is an extension to [[OpenGL]] for doing flexible off-screen rendering, including rendering to a [[texture (computer graphics)|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 The use of FBOs doesn't suffer from the overhead associated with OpenGL drawing context switching, and has largely superseded the [[pbuffer]] and other methods involving context switches.

== Uses ==
The FBO has two main uses: The post-processing of rendered images and composition between different scenes.
Some examples are:
# The rendered image is captured and subjected to [[Fragment Shaders]] or other manipulations. This allows for many of today's popular computer graphics effects to be carried out, including the addition of a blurring or bloom effect.
# Can be used to create views of other scenes, for example: a TV in a house showing the view from a secondary camera. A scene can be rendered through an FBO to a texture, then that texture can be applied to the surface of a TV. This is sometimes called "Render to Texture" or RTT.

== Advantages over other methods ==
Methods involving the FBO are considered superior because:
* It is easier to set up than most other methods.
* Does not require context switching.
* Is more efficient because resources are shared within the same context.
* Is more flexible because all of [[depth buffer]], [[stencil buffer]], etc. can be acquired.

== Architecture ==
To use an FBO one simply creates an instance of it. Along with the FBO come several attachments. One can then attach these to a chosen receiver: either a [[Texture (computer graphics)|texture]], or a [[render buffer]].

For example:
* Create an FBO and bind it.
* Attach the color buffer (either as a RenderBuffer or a texture) to the FBO.
* Attach the depth buffer (either as a RenderBuffer or a texture) to the FBO.
* Bind the native window FrameBuffer (id=0)
* Render the texture to screen with a pixel shader, dependent on both the Color information and depth information.

== External links ==
* [http://oss.sgi.com/projects/ogl-sample/registry/EXT/framebuffer_object.txt Framebuffer object technical paper] {{Webarchive|url=https://web.archive.org/web/20130502110335/http://oss.sgi.com/projects/ogl-sample/registry/EXT/framebuffer_object.txt |date=2013-05-02 }}
* [https://web.archive.org/web/20070108122530/http://openvidia.sourceforge.net/fbo.shtml Framebuffer object reference at openvidia]
* [http://www.songho.ca/opengl/gl_fbo.html Example code for Windows and Linux]
* [https://web.archive.org/web/20131101002803/http://www.opengl.org/wiki/GL_EXT_framebuffer_object EXT Framebuffer] (opengl.org)

[[Category:OpenGL]]

Framebuffer object - Revision history

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