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LSL Wiki : Simulator

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The Second Life world consists of many, interconnected, uniquely-named simulators (also referred to as sims or regions) positioned on a Cartesian map with its origin at the global coordinates 1000, 1000 (Da Boom sim). A sim's global coordinates can be accessed by calling llGetRegionCorner and dividing the results by the size of a sim (256m on a side). Neighbouring sims are connected vertically and horizontally, but never diagonally. This grid forms the world (image) of SL. Sims also seem to have an integer that represents a group of users for which the sim shows up on the world map (there are hidden sims; if you are in a hidden sim, all other hidden sims designated to the same group will show up on the world map).

The dimensions of a sim are unvaried: 256m x 256m. Non-physical Objects instantly move down to 4096 meters if they go above 4097 meters on the z axis (height) if they move after going above 768 meters. (physical objects currently go off-world at 4096m). Sims always have land, although it can be completely submerged in water. Any open space between non-adjacent sims is visibly rendered as water on the client, but cannot be accessed (the avatar will bounce off an invisible wall).

There is currently a limit of 15,000 primitives per sim, and approximately 100 agents. Though intended to optimize server and client performance, these numbers are arbitrary and likely to be increased again in the future. (Initially, the limit was 10,000 prims and approximately 20 agents.)

Open-space sims (also known as void sims) have a limit of 3750 primitives per sim. A agent has to own a standard sim to get Open-space sims.

A sim keeps track of the objects and agents within it, simulates physics, runs scripts, and caches and delivers object and texture data within the sim to clients, both within ("agents") and looking into the sim ("child agents"). Sims also handle attachments, which are really just special objects that match an avatar's location and rotation, and don't count against the sim's prim limit.

Simulator names are restricted to 20 characters(counting spaces) which may be split into 3 alphanumeric words.


Land | Time | Weather

Function Purpose
llCloud Returns cloud density.
llEdgeOfWorld Determines off-world locations.
llGetDate Returns current date.
llGetGMTclock Returns time since midnight in GMT.
llGetLandOwnerAt Returns the land owner at a given location.
llGetParcelFlags Returns a bitfield of the parcel's flags, eg. allows outside scripts, etc.
llGetRegionAgentCount Returns the number of agents in the region.
llGetRegionCorner Returns simulator's position in global coordinates.
llGetRegionFlags Returns a bitfield of the region's flags, eg. sandbox or terraforming status.
llGetRegionFPS Returns the FPS of the sim the script is running in.
llGetRegionName Returns the name of the sim the script is running in.
llGetRegionTimeDilation Returns the time dilation of the sim the script is running in.
llGetSimulatorHostname Returns the simulator's location on the Internet.
llGetSunDirection Returns a vector pointing towards the sun from the object's current position.
llGetTimeOfDay Returns the time in seconds since simulator midnight.
llGetWallclock Returns time since midnight in PST.
llGround Returns ground height.
llGroundSlope Returns ground slope.
llGroundNormal Returns the normal vector to the ground.
llGroundContour Returns ground contour.
llModifyLand Changes the height of the land the script is over.
llOverMyLand Determines if object is over land owned by the object's owner.
llParcelMediaCommandList Changes parcel video settings.
llParcelMediaQuery Returns parcel video settings.
llRequestSimulatorData Returns simulator properties via the dataserver event.
llSetParcelMusicURL Controls parcel music settings.
llScriptDanger Determines if land is editable, allows rez, and disallows scripts.
llWater Returns water level height.
llWind Returns wind velocity.

Technical Specs

Each sim is powered by a single PC CPU core, either an , running Debian Linux, though there may be multiple CPUs, cores, and sims per machine (1100 servers, ~2000 CPUs -2/22/06) or strona. There are no more than 4 sims per machine (2 dual-core CPUs per box).

Open-Space Simulators are run on the same servers as the main ones, but they are packed 4 to each CPU core.

Apparently, the sim software uses a pretty sophisticated journaling storage system (database) for objects, allowing a fast (usually) recovery with minimal data loss after a crash, power outage, etc.

"The company [Linden Lab] also chose to store the avatars that its nearly 60,000 users [10/17/5] have created in a file system front-ended by the open-source Apache Web server, while the open-source Squid Web proxy cache keeps the data conveniently nearby. Metadata about the avatars is stored in an open-source MySQL database."

Updated Specs

"Second Life has 240,000 registered users. ... Second Life currently runs on 2,579 servers that use the dual-core Opteron chip produced by AMD. Each server is responsible for an individual "sim," or 16 acres of virtual "Second Life" land. At peak usage that means that each server is handling about three users." -

Jakarta Hotel
Rumah Dijual
Rental Forklift
Properti Semarang
Perlengkapan Bayi
GPS Tracking
Outsourcing service Indonesia
Toko Bunga
Building Signage

Functions | sim names
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