Framebuffer object: Difference between revisions

Revision as of 22:26, 30 January 2008

Revision as of 05:13, 27 February 2008

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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. 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 The use of FBO's doesn't suffer from the overhead associated with context switching, and has largely superseded the [[pbuffer]] and other methods involving context switches.

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 The use of FBO's doesn't suffer from the overhead associated with context switching, and has largely superseded the [[pbuffer]] and other methods involving context switches.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 [[Pixel Shaders]] or other manipulations. This allows for many of todays ''popular computer graphics effects'' to be carried out, including the addition of a blurring or bloom effect.

2.# Can be used to create views of other scenes, for example: a TV in a house. 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 ==

1. The rendered image is captured and subjected to [[Pixel Shaders]] or other manipulations. This allows for

many of todays ''popular computer graphics effects'' to be carried out, including the addition of a blurring or bloom

effect.

2. Can be used to create views of other scenes, for example: a TV in a house. 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:

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* Is more flexible because all of depth buffer, stencil buffer, accumulation buffer, etc. can be acquired.

== Architecture ==

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

attach these to a chosen receiver; either a [[Texture (computer graphics)|texture]], or a [[render buffer]].

For example:

* Create an FBO.

* Attach the color buffer to a texture.

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* Render the texture to screen with a pixel shader, dependent on both the Color information and depth information.

== External links ==

=Links=

Framebuffer object technical paper. [http://oss.sgi.com/projects/ogl-sample/registry/EXT/framebuffer_object.txt]

Framebuffer object reference at openvidia.[http://openvidia.sourceforge.net/fbo.shtml]

Framebuffer object technical paper.* [http://oss.sgi.com/projects/ogl-sample/registry/EXT/framebuffer_object.txt Framebuffer object technical paper]

* [http://openvidia.sourceforge.net/fbo.shtml Framebuffer object reference at openvidia]

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