F

face

A single polygon in a mesh.

fade

The period between the central, or sustain, portion of a force feedback effect and its end.

falloff

Light attenuation that occurs between a spotlight's inner and outer cones.

field

Data for one-half of a single video frame within a video stream. Each field contains data for every other scan line. Fields are sent and received in odd field, even field order.

field polarity

Quality determining whether a field is an even field or an odd field. Odd fields are defined when the trailing edge of VREF does not occur during a scan line. Even fields are defined as when the trailing edge of VREF occurs during a scan line.

flimmering

A shimmering appearance on 3-D primitives that results from a poor separation of z values when doing decaling. Some pixels from the back texture are rendered onto the front texture and visa versa.

flip

The process of swapping the addresses associated with the back and front buffers. This effectively swaps the image in the back buffer to the front buffer, thereby displaying the image.

flipping chain

A series of surfaces, attached to each other, that can be flipped. See also flip.

flipping surface

Any piece of memory that can be flipped. See also flip.

focus window

An application window, visible or not visible, that DirectDraw uses to hook window messages. The focus window's message handler receives input messages as forwarded by DirectDraw. Applications can have only one focus window. See also device window.

frame

An invisible box that provides a frame of reference for objects in a scene. Objects can be placed in a scene by specifying their spatial relationship to a relevant reference frame. Visual objects take their positions and orientations from frames. Also, a single image from a movie or animation.

front buffer

The first buffer in a flipping chain. In many cases, this will be the visible primary surface. In other cases, such as a flipping chain of textures, the front buffer is the surface the 3-D engine will get the texture from, but it is not the primary surface and is not displayed. In the case of flipping overlay surfaces, the front buffer is displayed, but is only a surface overlaid on the primary surface. See also primary surface.

front clipping plane

The near boundary of a viewing frustum. Any object closer to the camera than the front clipping plane is not rendered. The height of the front clipping plane defines the field of view. See also back clipping plane.