What Was New in Xelagot 3.3?
xelagot 3.3 is dedicated to Roland Vilett

2002, November 13th

• A new version of Xelagot 3.310 fixes a memory leak apparent only if the bot is used for many hours or days. This bug affects all xelagots (x1, av99bot and srvcXlgbot) since versions 3.3 (also the 3.4 beta version), and all versions are now patched (thanks BCat).
  
   
   

2002, September Friday the 13th

• A new version of Xelagot 3.309 fixes a bug I discovered today in the property query code, and which dates from as far as 3.1 or possibly earlier versions: if the bot's Object cache is used for querying (surveying) property, old deleted objects may sometimes reappear in the surveys and in backups. Because of this bug, some scripts may fail to work at apparently random moments. This is a serious bug, as it affects the core of the xelagot code (all bots, including av99 and srvcXlg are affected), so please upgrade!

  
  The functions affected are:

  • verbal command queries
  • all surveys made by querying with the Survey Manager if the cache is used
  • action script surveys with "QueryAt @a" that do not specify "QueryUseCache OFF"
  • action script "ProjectBackup" as from Xelagot version 3.3 (before that version, the cache was never used for this function). This includes the functioning of the world backup scripts distributed with X1 (they are safe to use after upgrading)

  Not affected are:

  • backups/propdumps made with the Survey Manager's "Backup" tool using the iteration method
  • "ProjectBackup" scripts used before Xelagots version 3.3

  Note that this bug does not make you lose objects, but it will add unnecesary objects and may cause the Object Inspector to squeak. It can cause bot malfunction in scripts.
   

2002, Wednesday August 21st

• The Terrain Manager can now upload (and modify) empty pages. To understand this, we must have a look at what the world server does: if a terrain page has never been edited (modified), as for example, a terrain page has never been touched or the terrain has just been deleted, the world database does not have any data for that page (pages are 128x128 coords square, a world up to 64N only has one page). When you backup the terrain and create your elevdump file, nothing is sent for non-existing pages... and you can't modify those pages with a bot using that file. x1 version 3.308 will create, on demand, the missing data. You can specify up to which world coordinate this must be done: a 0 value will automatically grab the world size, and you can add and modify as many empty pages as you wish. For example, you wish to make the terrain lower by 10 metres, and your world is up to 50N. You can specify that the terrain be lowered up to 250N if you wish... the bot will add the missing pages (lowered by 10m) to the database: the result will be your 'legal' central page, and 24 others around it :)
  Thanks, Tengel, for pointing out this problem.
   

• Access violation on closing x1: at high heartbeats, if the Map was open and one launched a url (e.g. by double clicking on one in the chat screen), the url launcher would cause an access violation when closing the bot application, due to a Microsoft failure in connecting back to the launching window when issuing a ShellExec command (the function would never return). Fixed by limiting the refresh speed of the Map.
   

2002, Saturday August 17th

2002, Wednesday July 31st

This is a maintenance release. Bug fixes:

• The Mute and Ignore attributes of avatars were not working. The Mute attribute silences someone in the chat window and log files, the Ignore attribute forces the bot to ignore that person's chat. Fixed (thanks BCat).
• The Action Script's OnQueryBeginEvent was being triggered multiple times when doing a ProjectBackup, instead of once. Fixed (thanks Just In).

This is the last update of the 3.3 series using AW SDK 24. Further updates will be 3.4 beta.

2002, Tuesday July 2nd

Features:

• World list can be sorted by name or number of visitors.
   
• The Log files now have their own folder: Logs. Their name has changed slightly: they all start with Log and the bot number (01, 02, etc.), followed by Chat, Tech or ChatTech. Log files have a limited size: when this is exceeded, the file gets renamed (the VRT date and time are appended) and a new file is started. The default size is 1 megabyte, this can be increased in the ini file section [Parameters], key MaxLogSize (value in bytes). There is no restriction to the amount of files, so empty the Logs folder regulary.
   
• Additional verbal commands for Random motion and Blimp motion.
  • go random, go random here and go random there have different meanings now: here is at the position of the speaker, there is at the position of the bot, go random only does not change the settings; they all start off the random motion
  • set random center here (or centre) and set random center there follow the same idea, but only change the centre of motion, and may be issued whether the bot is 'randoming' or not
  • set random center at coords allows you to specify the coordinates
  • go blimp, go blimp here, go blimp there, set blimp center here, set blimp center there, set blimp center at coords are similar commands for blimps
  • additional verbal commands for blimps (distances are in metres): set blimp clockwise, set blimp anticlockwise, set blimp radius radius1 sets circular motion, set blimp radius radius1 radius2 sets elliptical motion, set blimp step step, set blimp guide distance, set blimp cells number sets the number of cells for terrain sensing, set blimp terrain ON/OFF sets terrain sensing on or off, set blimp terrain ON/OFF altitude sets also the values of minimum and maximun altitude above terrain to the value of altitude, set blimp terrain altitude does not interfere with ON/OFF setting. The min and max altitudes can be set separately with these two commands: set blimp terrain ON/OFF min max, and set blimp terrain min max.
  
   
• Action Script statements.
  • PlaySound $filename is an old undocumented statement to play a wav file.
  • Beep gives a standard windows beep.
  • ConMsgAll $msg
    ConMsgAllConcat list of variables
    ConMsgAllText %speed /s_List [$m]
    ConMsgAllText %speed text-label [$m]
    send a console message to all avatars present (caretaker bots only, 3.3 statement). See version 3.300 for more about console message statements.
  • IfGetTerAlt %a @b statement tests whether a terrain page has been downloaded at location @b, and if so stores in metres (with a high precision) the value of the terrain altitude at that point in variable %a and executes the statement (an optional else clause can follow).
  • IfGetTerAvAlt %a @b statement is similar to the previous statement, but the altitude stored is where the avatar has to go (mainly, the bot), and the precision is 1 cm. In my calculations, the bot uses a bounding base of 50x50 cm sq. AW may use different values. On flat terrain, both statements give the same result, on slopes the result is different (the avatar is above the terrain).
    NOTE: the bot downloads the page it is on whether terrain is enabled (i.e. visible) or not, and any page within 350m of its position. It will keep a downloaded page until it is at a distance of 480m away from it. These two statements do not test whether the world has disabled or enabled terrain (but it does test the world build number). To test for enabled terrain, use the following statement:
  • IfHasTerrain statement tests the world build and whether terrain is enabled: i.e. tests whether there is a visible terrain.

Bug fixes:

• Rounding off error in Edit Teleport fixed.
• clicking the GUI blimp apply all data and execute button was not setting the guide distance; fixed.
• Scanav had a limit radius of 1000m when no radius was specified, instead of no limit. Fixed.

2002, Monday June 24th

Features:

• Automatic terrain download and cacheing in the background. This allows the bot to sense the terrain around it. The terrain cache directory is called Terrain (just as the objects cache directory is Objects). The maximum cache size is regulated by the same ini file parameter as that for the objects cache size (in bytes): section [Parameters], key MaxCache. The default value is one megabyte (1048576 bytes). Each cache's size is regulated separately, so the total maximum cache size is twice the MaxCache value!
   
• Ability to accurately follow terrain heights.
   
• Practical application of terrain sensing:
   
  • Random Motion is able to sense terrain (GUI, Action Script).
    The bot can follow terrain: a maximum and minumum height above the terrain can be specified. To have the bot follow the terrain accurately, set both maximum and minimum to zero. In the GUI, terrain sensing is enabled by default. It can be adjusted per world, the bot will remember the settings between sessions. In the Action Script, all terrain sensing settings for the script are set to default and disabled when a script starts running. This allows older scripts to work as they used to: no terrain sensing. They do not affect the GUI settings (the bot will use the appropriate set, depending on what started the motion: GUI or Action Script).
     
    Action Script statements.
    RandomTerSensing ON/OFF
    enables or disables terrain sensing. Default = OFF.
    RandomTerMaxAlt %alt
    sets the maximum distance above terrain in metres. If this is lower than the minimum altitude, it is disregarded. Default = 0m.
    RandomTerMinAlt %alt
    sets the minimum distance above the terrain in metres: nearer to the terrain is not allowed. Default = 0m.
    Note: Random Motion can also be started with verbal commands. There are as yet no verbal commands to change Random terrain sensing parameters, this must be done using the GUI. For av99 and srvcXlg, edit the ini file: RandomTerON (boolean, 0 OFF, 1 ON), RandomTerMaxAltitude, RandomTerMinAltitude (cm).
     
  • Blimp motion is able to sense terrain (GUI, Action Script).
    The bot can be forced not to go lower than a specified number of metres above the terrain, and a maximum height above the terrain can also be specified (but this is not usually needed).
    The terrain sensing 'radius' (in cell units) can be specified too. This allows for small and large blimps to work properly: a blimp 20m long at a speed of 2.00m/sec would use a sensing radius of 3 cells, a smaller blimp may do with 2 cells, a normal avatar or small bird can use the 0 cell setting, then the sensing will be very accurate.
    If no altitude corrections are needed, the altitude of the motion centre is used.
    The blimp motion (with or without terrain sensing) is guided by an invisible point at a distance in front of the bot. The distance to this guide affects the climbing slope: 5m gives a smooth effect, the minimum value is 2m. This distance is now customizable.
    In the GUI version, Blimp terrain sensing is enabled by default, settings are adjustable per world. Av99 and srvcXlg set their GUI parameters in the ini file (but they can not be used, since there is no verbal command to do this).
     
    Action Script statements. As for Random Motion, these are disabled by default.
    BlimpTerSensing ON/OFF
    enables or disables terrain sensing. Default = OFF.
    BlimpTerMaxAlt %alt
    sets the maximum distance above terrain in metres. If this is lower than the minimum altitude, it is disregarded. Default = 0 (disregarded).
    BlimpTerMinAlt %alt
    sets the minimum distance above the terrain in metres: nearer to the terrain is not allowed. Default = 5.00m.
    BlimpTerCells %number
    sets the number of terrain cells to each side of the bot that the terrain sensor has to take into account. For a 20m long blimp at 2m per second, 3 cells is fine. The faster or larger the blimp, the more cells are needed. 3 cells is default.
    BlimpGuideDist %dist
    sets the distance of the guiding point. The minimum distance is 2.00m, 5.00m usually is a good setting. Note: this parameter does not belong to the terrain sensing functions, it is used by normal blimping too.
     
  • The Action Script To statement can also sense terrain:
    ToTerSensing ON/OFF
    enables or disables terrain sensing. Default: OFF.
    ToTerMaxAlt %alt
    sets the maximum altitude above the terrain. Diasabled if < ToTerMinAlt. Default = 0 (enabled).
    ToTerMinAlt %alt
    sets the minimum altitude above the terrain. When both ToTerMinAlt and ToTerMaxAlt = 0, the bot follows the terrain exactly. Default = 0.
     
  • The Action Script Walk statement senses terrain:
    WalkTerSensing ON/OFF
    enables or disables terrain sensing. Default: OFF.
    WalkTerMaxAlt %alt
    sets the maximum altitude above the terrain. Diasabled if < WalkTerMinAlt. Default = 0 (enabled).
    WalkTerMinAlt %alt
    sets the minimum altitude above the terrain. When both WalkTerMinAlt and WalkTerMaxAlt = 0, the bot follows the terrain exactly. Default = 0.
     
  • Avatar Map has terrain sensing ON by default, this may be changed using the menu or F Key combinations. To sink below the terrain, it must be disabled with Ctrl + F6, it can be re-enabled with Ctrl + F5. Flying up and down above the terrain and sticking to terrain works like in AW: going out of contact with the terrain (numeric + key) allows you to fly freely, making contact with the terrain makes you stick to it.
     
  • The little known, but documented, verbal command Walk uses terrain sensing. Because it is actually using the Avatar Map's Up arrow key (even if the map is closed), it sets terrain sensing ON in the Avatar Map.
     
• Other possible applications are for the Go to, Join, Follow functions. These present the major problem of when to actually apply terrain sensing. Possibly, I'll have to add verbal commands to allow the owner to adjust this behaviour at will, as well as script and GUI contols. A few possible problems and conflicts have to be solved, for example:
   
  • clashes between Action Script and GUI settings
  • loss of contact with person followed
  • as the bot does not 'see' objects, how would it know when to stick to terrain or not when following?
  • how to handle terrain holes
  
  This version does not have all the possible applications of terrain sensing. Better slow than careless...

Bug fixes:

• Loading Skybox settings from file using the GUI World Attributes page and then saving this to the Editor was not updating the Skybox field; instead, it was updating the Ground field with the Skybox name. Fixed (thanks Levi).
• Processor stack overflow when calculating large distances, especially in Global Mode (EInvalidOp). Fixed (thanks P0t).
   

2002, Tuesday June 18th

• 3.3 Caretaker bots are able to give a world Announce Console Message when an avatar enters, similar to the world Announce all bots can give. The same rules apply: once the Announce is given, it will not be repeated each time the avatar enters until the time-out expires (10 minutes after the last time the avatar left, this can be changed in the ini file, look for NoGreetInterval=10), or the avatar can not be identified. The time-out also occurs if the text of the message is changed and an avatar enters again. This message can not be limited to a certain area, as is possible with the normal world Announce, but bots can be excluded from receiving it.
   
• Corrected a problem in the storage of angles, which I introduced in version 3.300. Now as in pre 3.3 versions, all angles are stored within the range 0.0 to <360.0. This makes angle comparison easy. This range had been changed to -360.0 to +360.0, which caused confusion.
   
• As from this version, all avatars store their coordinates and angles as floats, not as integers. This change was prompted by the limitation imposed by integers when calculating movement. At small positional or angular changes, especially at high heartbeats, the bot would freeze or fail to rotate: the change would be smaller than the integer unit value. Example: the bot has to rotate left 0.7 degrees per second, i.e. 7 deci-degrees, the integer storage unit. At 16 heartbeats per second, this gives 0.4375 deci-degrees per heartbeat, which rounds off to 0. This could cause the Blimp to always face the same way :)
  This change does not affect objects or locations in the Action Script, but is reflected in the Person variables. Person to Person transmission of location and angle data, and all turn and distance operations will use and store floats in Person variables, and store rounded off integer values in the other Location variables.
   
• As a result of storing avatar coordinates in floats rather than integers, the bot's heartbeat can now reach 64 beats per second. In the menu Bot | Heartbeats per second the heartbeat can be adjusted from 2 to 64 (was 2 to 16).
   
• I re-wrote the Blimp code to reflect the new use of floats and higher heartbeats. The problems with Blimp seem to have been solved.
   
• Property Queries (Zone Surveys) are now done according to the type of world server: in AW 3.2 world server build 33 or higher builds the bot does a 5x5 query (i.e. it queries a large zone containing 25 sectors, 400x400 square metres of land); in older builds it does the traditional 3x3 query (9 sectors, 240x240 square metres). The 5x5 query, introduced in AW 3.2, was never applied by the bot until now. The advantage of 5x5 is that Live Update covers a larger zone.
  Note: the Action Script Backup works always with 3x3 queries, no matter what world build.
   
• Action Script additions:
   
  • IfPerson &p IsAnnouncedConMsg statement
    IfPerson &p IsNotAnnouncedConMsg statement
    test whether &p has received a world Announce Console Message.
  
   

2002, Thursday June 13th

New features in 3.302:

• The 3.3 Terrain Manager has been enhanced. Caretaker bots' feature Restore Terrain has been renamed Upload Terrain, and has the following features:
   
  • Invert altitudes
    What's up goes down and vice-versa. Similar to scaling by -1.
     
  • Scale
    Altitudes can be rescaled. The default is 1.0, no rescaling. Larger than 1 enlarges (2.0 is dubbling), smaller makes smaller. 0 flattens the terrain (preserving the textures), negative numbers rescale and invert the altitudes (instead of using negative scaling, you can simply enable Invert altitudes).
     
  • Shift altitudes
    Shifts all altitudes (after eventually scaling and inverting) by a fixed amount. Positive is up, negative is down. Input in metres.
     
  • Maximum and minimum altitude
    Limit the highest and lowest altitudes. The utmost limit is of course the one imposed by AW: 327.67m and -327.68m.
     
  • Delete world terrain before uploading
    When selected (default) forces a full terrain reset before uploading.
     

2002, Monday June 10th

New features in 3.301:

• There is a new 3.3 Terrain Manager, that has the following functions:
   
  • Backup terrain
    This allows bots to make a full backup of the terrain pages. This elevdump file is 100% compatible with the one used by the remote Admin program. The actual jpgs are not backed up!
     
  • Restore terrain from backup
    Caretaker bots can restore the terrain from an elevdump file (but not the jpgs). Restoring is automatically preceded by a total terrain deletion.
     
  • Delete the terrain
    Caretaker bots can reset the whole terrain to the default values: 0 altitude, terrain0.
     
  
   
• Reload registry  (3.0 up)
  The World Attributes tab Varia has a new button for Caretaker bots to force the world to reload the world registry file, without having to stop the world.
   
• Action Script additions and changes:
   
  • The AvatarScan event can now use the Reply version of Say, Whisper and ConMsg: ReplyS, ReplySConcat, ReplySText, ReplyW, ReplyWConcat, ReplyWText, ReplyC, ReplyCConcat, ReplyCText. Up to this version only Say, SayConcat, Whisper &p, etc could be used in this event handler.
     
  • The execution of AvatarScan has changed slightly. When Scanav is called inside an event handler, the AvatarScan event is now triggered inmediately after exiting the event handler. Previously, all events were first handled and then one cummulative AvatarScan event was triggered; this did not work as expected. Another change is that you can not call Scanav inside an AvatarScan event handler any more (sounds logic, but if someone did that by mistake the bot would enter a non ending recursion and the program would run out of memory and crash).

Note: The terrain functions have been extensively checked in a world extending to 250N kindly made accessible by Andras. Thanks, Andras!

2002, Friday May 31st, on Roland Vilett's last day as Active Worlds programmer.

New features (the user interface features apply only to X1):

• 3.3 World Attributes Search Keywords, Entry Point, Enable Terrain and Enable 3-Axis Rotation can be managed by Caretaker bots through the user interface and the Action Script.
   
• Caretaker bots in 3.3 worlds can send a Console Message to an avatar. This is a sort of impersonal whisper which can be sent in plain, bold or italics and in any colour, and which is printed on the browser's chat window. The new Xelagot can do that too through the pop-up menu of individual avatars in the Presence List. It can also receive console messages. New statements and an Event handler have been added to the Action Script.
   
• Caretaker bots in 3.3 worlds can enter the world in the new Global Mode, which allows them to perceive avatars and their events in the whole world. These events can also be perceived while the bot is invisible, but the bot can not interact with the avatars, except for these actions: warp and teleport an avatar, send a url, eject and send the new Console Message to an avatar.
   
• There is a new 3.3 World Eject Database management, complementing the 3.2 version. This includes the old IP Blocking and two new categories: Blocking by Computer ID and Blocking by Citizen Number. When an avatar is ejected from a 3.3 world, these 3 blockings occur and are registered in the world database. The Xelagot's Eject Database Manager (in the Word Attributes screen) lets you change these records and add new ones. Records can be sorted by clicking on the column headers.
   
• When avatars (or bots) click on objects, the new 3.3 world server sends a full description of this object to SDK clients (bots), without the bot having to survey the area. The Xelagot's Object Manager, which did not serve much purpose, has now been enhanced with full ability to receive and display these 'clicked' objects. Bots in 3.2 worlds can use this feature too, but they must be surveying the area.
   
• The same Object Manager lets you build and delete individual objects in the world in normal or ED modes. This works with all 3.x world servers. Objects can now be copied from the Object Manager to the project and buffers. Previously, one could only send an object from the project to the Object Manager. Full 3-axis rotation has been added. Rotate by clicking on the arrow buttons: hold SHIFT for finer control, SHIFT + CTRL for maximum precision.
   
• The Login dialog box and all Teleport dialogs are enhanced with a few options: (1) stay in the universe or enter a world, (2) enter invisible or visible, (3) use Global mode or not (only for Caretaker bots in 3.3 worlds). All teleport facilities are now clearly marked with the teleport sign.
   
• Propdumps and XLG project files can now handle all AW formats (including the new 3.3). Reading these files is handled automatically, saving is a matter of choice. To do: Action Script statements related to AW propdumps.
   
• New 3.3 Action Script statements:
   
  • World Attributes (Caretaker bots)
    Allow3AxisRotation ON/OFF
    EnableTerrain ON/OFF
    WorldEntryPoint @coordinates
    WorldKeyWords $words
     
  • Console Message Event installer
    OnConsoleMessageEvent eventLabel
     
  • in the Console Message Event handler
    GetEventType %t  (returns 8440)
    GetChatline $a  or  GetMessage $a
    GetMessageColor %red %green %blue  (0-255)
    GetMessageStyle %bold %italic  (0 is off, <> 0 is on)
    IfChatIsConsoleMessage statement (tests whether the event handler is a console message one)
     
  • sending a Console Message (Caretaker bots)
    ConMsgColor %red %green %blue  (0-255)
    ConMsgStyle %bold %italic  (0 is off, <> 0 is on)
    followed by
    ConMsg &p $a
    ConMsgConcat &p <list of variables and strings>
    ConMsgText &p %speed /s_list
    ConMsgText &p %speed textLabel
    in certain Event handlers, where the avatar causing the event is defined, the following statements can be used
    RelpyC $a
    ReplyCConcat <list of variables and strings>
    ReplyCText %speed /s_list
    ReplyCText %speed textLabel
     
  • checking and removing text from a Console Message before it is sent (Caretaker bots);
    this applies to text sent with the Text variant, like ConMsgText
    IfConMsgTo &p statement
    IfConMsgToAny statement
    KillConMsgTo &p
    KillConMsg
    note: similar statements have been added for Say and Whisper buffers, if they were not yet implemented. IfSaysTo, IfSaysToAny, IfWhispersTo, IfWhispersToAny have lost the 's': IfSayTo, IfWhisperTo, etc (old statements remain valid). The new statements are KillSayTo &p, KillSay, KillWhisperTo &p, KillWhisper.
     
  • Global Mode (Caretaker bots)
    GlobalMode ON/OFF  prepares the Global Mode
    it must be followed by an Enter Command (for the bot to exit and reenter in the new mode), for example: Enter  or  EnterInvisible
    IfGlobalModeOn statement
    IfGlobalModeOff statement
    both test the status of GlobalMode preparation (this may be tested even before logging in); the next statements are only meaningfull when the bot is inside a world:
    IfMayGlobalMode statement
    IfMayNotGlobalMode statement
    test, inside the world, whether the world server is 3.3 compliant and supports Global Mode, and whether the bot is Caretaker and therefore is allowed to use Global Mode
    IfHasGlobalMode statement
    IfHasNotGlobalMode statement
    test, inside the world, whether the bot is actually using Global Mode
     
  • 3-axis rotation statements
    GetCoords various parameters  retrieves the coordinates, not the rotation angles
    The old GetLocation  retrieves coordinates, rotations and world, and GetPosition  retrieves coordinates and rotations but not the world
    GetRotations various parameters  (notice the plural form) retrieves the 3 rotations: Yaw, Tilt and Roll
    GetYaw various parameters  is the same as GetRotation
    GetTilt various parameters  retrieves the Tilt angle
    GetRoll various parameters  retrieves the Roll angle
    LocClearRotations @a  puts Yaw, Tilt and Roll to zero
    LocYawBy @a %b  is the same as LocTurn @a %b, i.e. it adds %b degrees to the the Yaw angle
    LocTiltBy @a %b  adds %b degrees to the the Tilt angle
    LocRollBy @a %b  adds %b degrees to the the Roll angle
    LocYawTo @a @b  is the same as LocTurn @a @b, i.e. it turns the Yaw angle @a so that it faces @b
     
  • new extended coordinate notation
    Two rotation angles had to be added to the coordinates of objects: Tilt and Roll. The new notation looks like this:
    23.000w 30.500s 1.60a 45.0° 15.0t -15.0r
    where 15.0t -15.0r represent the Tilt and Roll angles.
    45.0° is the familiar Rotation, which is now called Yaw (as it allways was in the SDK); the degrees symbol ° may be omitted
    if the Tilt and Roll angles are both zero, then the old notation is used:
    23.000w 30.500s 1.60a 45.0°
    although 23.000w 30.500s 1.60a 45.0° 0.0t 0.0r is valid
  
   
• The Avatar Map has had a facelift too, and many small but handy additions, most of them can be used in older worlds. The right-click pop-up menu has been installed as a 'real' menu and can also be accessed by right-clicking on an empty place on the map. In front view map, a left-click on an avatar is like doing that in the browser. A right-click on an avatar brings up a menu to whisper, go to, teleport, send url or console message, eject... most functions that you also find in the Presence list menu on the main screen. Another small feature is a local teleport button (accessible also with ALT+T): type your coords and hit ENTER to teleport, or ESC to cancel.
   
• The big missing feature at present is Terrain. I still have to study this subject, maybe in some future version I will be able to include Terrain related functions...