F

face

One side of a polygon. Each polygon has two faces: a front face and a back face. Only one face is ever visible in the window. Whether the back or front face is visible is effectively determined after the polygon is projected onto the window. After this projection, if the polygon's edges are directed clockwise, one of the faces is visible; if directed counterclockwise, the other face is visible. Whether clockwise corresponds to front or back (and counterclockwise corresponds to back or front) is determined by the OpenGL programmer.

flat shading

Refers to coloring a primitive with a single, constant color across its extent, rather than smoothly interpolating colors across the primitive. See Gouraud shading.

fog

A rendering technique that can be used to simulate atmospheric effects such as haze, fog, and smog by fading object colors to a background color based on distance from the viewer. Fog also aids in the perception of distance from the viewer, giving a depth cue. See also depth-cueing.

font

A group of graphical character representations usually used to display strings of text. The characters may be roman letters, mathematical symbols, Asian ideograms, Egyptian hieroglyphs, and so on.

fragment

Graphic data generated by the rasterization of primitives. Each fragment corresponds to a single pixel and includes color, depth, and sometimes texture-coordinate values.

frame buffer

A stack of bitplanes. All the buffers of a given window or context. Sometimes includes all the pixel memory of the graphics hardware accelerator. See also bitplane.

front face

See face.

frustum

The view volume warped by perspective division.