P

page flipping

See flip.

palette

The set of colors used by an object or application. In DirectX, a DirectDrawPalette object.

palette index

An integer index into the palette table array that is used to select a particular color.

palettized surface

A DirectDrawSurface object that uses an attached palette to contain color information.

pan value

The relative volume, measured in hundredths of decibels, between the left and right audio channels.

parallel point

Description of a light source that illuminates objects with parallel light, but the orientation of the light is taken from the position of the parallel point light source. For example, two meshes on either side of a parallel point light source are lit on the side that faces the position of the source.

PChannel

Performance channel. A PChannel is a MIDI channel in a particular channel group on a particular port.

peer-to-peer session

A DirectPlay session in which the session's complete state is replicated on all the computers in the session. The session description data—the list of players and groups and the names and remote data associated with each session—are duplicated on every computer. When one computer changes something, it is immediately propagated to all the other computers. This is the default mode of communication for DirectPlay. See also client/server session.

perspective correction

The technique of applying a texture map to a polygon that is angled away from the camera, interpolating so that the texture is stretched onto the polygon appropriately for the apparent depth of the polygon. Direct3D supplies perspective correction automatically.

pick

To search for visuals in a scene, given a 2-D coordinate in a viewport.

PID

Physical interface device. A USB class that allows humans to feel force feedback from a computer.

pitch

The distance, in bytes, between an address that represents the beginning of a bitmap line and the beginning of the next line. Do not confuse memory pitch and memory width, since not all display memory is laid out as one linear block. For example, with rectangular memory, the pitch of the display memory could include the width of the bitmap plus part of a cache. See also width and stride.

player

A single participant in a DirectPlay session. Each player is associated with a player ID that enables messages to be exchanged among players.

player ID

A unique number that is assigned to each participant in a DirectPlay session when the participant is created. The application can exchange messages among players by using player IDs. The host is always assigned the DPID_SYSMSG player ID.

point light

A light source that radiates equally in all directions from its origin.

point list

The simplest 3-D primitive. A collection of unconnected points in 3-D space.

power

In the specular property of a material, the value that determines the sharpness of specular highlights. A value of 5 gives a metallic appearance, and higher values give a more plastic appearance.

primary sound buffer

The buffer that the user hears when a game is playing. The primary buffer is generally used to mix sound from secondary buffers, but it can be accessed directly for custom mixing or other specialized activities.

primary surface

The area in memory containing the image being displayed on the monitor. In DirectX, the primary surface is represented by the primary DirectDrawSurface object.

projection space

Frame of reference containing vertices after they are modified from their world space locations by the projection transformation. Projection space is a homogeneous cuboid space in which all vertices in a scene have x- and y-coordinates that range from –1.0 to 1.0, and a z-coordinate that ranges from 0.0 to 1.0. Projection space is sometimes referred to as post-perspective homogeneous space.

projection transformation

The application of a matrix to vertices to change them from camera space to projection space.