Framebuffer Object

When Frame Buffer Object ( FBO) is called, the flexible and platform independent offscreen rendering allows an extension to OpenGL. It is comparable to the render target model of DirectX. Both extensions allow not only to render the window, but also apply almost all graphics operations on textures. By combining a plurality of such images ( texture ), or using various filters, visual effects can be generated.

The extension has many advantages over the previous pBuffer objects which could only be described by necessary context switches. This is not necessary in FBO, which both simplifies the programming, as also has advantages in speed.

Applications

FBOs are mainly used for two steps: In the post-processing of rendered images and in the compilation of several scenes within an image.

In the first case, the result is not output on the monitor but painted to a framebuffer object. Then to this filter, pixel shader, or the like can be used to produce, for example, blur effects or blooming.

In the composition of several scenes the image from the results of previous calculations is assembled. Such a scene is conceivable in which outside an apartment a camera is attached. Their image of the outside scene is stored in a texture ( Render to Texture or shortly RTT), which is " stuck " in a room of the house via a monitor and it enables the viewer a picture outside his own environment to see. Another example is the computer game Portal, in which this technology is used to rooms that are connected by portals to represent. But even simple mirror images or refractions in glass objects can be realized in this way.