S

saturation

Adjustment to the extreme value of a range when the actual value approaches the extreme. If the maximum value in a range is 1,000 and the maximum saturation point is set to 900, any value greater than 899 is adjusted to 1,000.

scene

The entire set of objects that make up a virtual environment, including visible objects, sounds, lights, and frames. In Direct3D, the entire set of objects is contained in a root frame.

screen space

Frame of reference in which coordinates are related directly to 2-D locations in the frame buffer, to be displayed on a monitor or other viewing device. Projection space coordinates are converted to screen space coordinates, using a transformation matrix created from the viewport parameters.

secondary sound buffer

A section of audio memory that stores individual sounds that are played throughout an application. The sound can be played as a single event or as a looping sound that plays repeatedly. Secondary buffers can also play sounds that are larger than available sound-buffer memory; the buffer serves as a queue that stores the portions of the sound about to be played.

secure session

A session in which all users have been authenticated against a database of known users before being allowed to join a session. In a secure session, all DirectPlay system messages are digitally signed to verify the identity of the sender. Certain system messages that carry sensitive information are encrypted. System messages that originate from one player and need to be broadcast to all the other players in the session are first sent to the server. The server then puts its signature on the message and forwards the message to all the other computers in the session. Player-to-player messages are not signed by default and are not routed through the server.

service provider

A dynamic-link library used by DirectPlay to communicate over a network. The service provider contains all the network-specific code required to send and receive messages. Online services and network operators can supply service providers to use specialized hardware, protocols, communications media, and network resources.

session

In DirectPlay, an instance of several applications on remote computers communicating with each other. Before an application can start communicating with other computers, it must be part of a session. An application can enumerate all the existing sessions on a network and join one of them, or it can create a new session and wait for other computers to join it. Once the application is part of a session, it can create a player and exchange messages with all the other players in the session.

sound buffer

A segment of memory that stores DirectSound audio data. Sound buffers can be primary or secondary, static or streaming.

source color key

A color that (in the case of blitting) is not copied to, or (in the case of overlays) not visible on, the destination.

specular property

The material property that determines how a point of light on a shiny object corresponds to the reflected light source. The specular property of a material is one of two properties that determines how a material reflects light. See also emissive property.

spotlight

A light source that emits a cone of light. Only objects within the cone are illuminated. The cone produces light of two degrees of intensity, with a central brightly lit section that acts as a point source, and a surrounding dimly lit section that merges with the surrounding deep shadow.

static sound buffer

A section of memory that contains a complete sound. These buffers are convenient because the entire sound can be written once to the buffer.

sticky focus

In DirectSound, the ability to play sound buffers when the owning application does not have the input focus. For example, a DirectSound application could continue to play a sound buffer while the user is working in another application.

streaming sound buffer

A small sound buffer that can play lengthy sounds because the application dynamically loads audio data into the buffer as it plays. For example, an application could use a buffer that can hold 3 seconds of audio data to play a 2-minute sound. A streaming buffer requires much less memory than a static buffer.

stretching

Blitting an image into a destination with different dimensions. This operation is supported directly by some hardware.

stride

Synonymous with pitch. See also width.

surface

Memory that represents visual images. This is often display memory, but it can be system memory. See also complex surface, off-screen surface, overlay surface, and primary surface.

sustain

The period during which the basic magnitude of a force-feedback effect is attained, after the attack and before the fade.

system message

In DirectPlay, a message from the player ID DPID_SYSMSG. All system messages begin with a DWORD value.