Selecting Scenery, .Vis Files and World Sets

To display scenery, the scenery system must be able to find the world sets included in Flight Simulator. The .vis file contains the information that points Flight Simulator to the world sets. Flight Simulator includes a file called World.vis, located in the Scenery directory; when Flight Simulator is installed, World.vis is set to point to all of the world sets that are included with Flight Simulator. When scenery disks are installed or when a user changes the scenery properties in the Scenery Library dialog box, World.vis is updated.

The .vis file contains many components. Much like A BGL file's header, a header points to all these components. The following example shows a World.asm file that, when assembled, becomes a World.vis file.

;BGL/LOGOL World.vis .Vis File includebglmac.asm include foreignv.asm BGLSEGsegmentwordpublic low64ksegment para public 'l64' low64kends ASSUMEcs:BGLSEG,DS:low64k,es:nothing

;SCENERY OVERLAY HEADER *************************************************** dwdriver_end;00 length of scenery overlay db'MR';02 type id 'MR' == BGL, 0xDD == F1 dwtitle_data;04 ptr to title dwdescription_data;06 ptr to description data dwworld_id_list;08 world set id ptr dwfile_and_type_list;10 file & type list dwbooster_list;12 booster processor list dwtag_list;14 tag list (must precede file & type list!) dw8 dup(0);16 spares ;32 Scenery info starts at 20h

SCENERY_DATAlabelbyte BGL;switch to BGL mode EOF;dummy database

TITLE_DATA labelbyte;31 char asciiz dbmsgvis005,0

DESCRIPTION_DATA labelbyte;256 char asciiz dbmsgvis001 dbmsgvis002 dbmsgvis003 dbmsgvis004 DD_endlabel byte db(256+DESCRIPTION_DATA-DD_end) dup (0)

WORLD_ID_LISTlabelword dw0001h;FS5 default world 1 visuals dw0003h;FS5 default world 1 VORs ADFs dw0004h;FS5 default world 1 ATIS Landme dw0000;eol EOLmacro db0 endm

;TAG LIST (FS5.1) ***************************************************** ; ;*** Important Note! *** ;This list must be maintained above FILE_AND_TYPE_LIST in the file, ;because JAPAN Scenery's Setup (which edits World.vis) isn't aware of ;the pointer to this list; this placement prevents the list from being updated. ;This list provides tags to associate with scenery areas, so it can be ;determined when a scenery area has been added again (or "overinstalled") by ;a setup program. ;TAG LIST ENTITY OPCODE DEFINITIONS - ;OpFormatDefinition ;----------------------------------------------------------------- ;0db0;00 opcode = EOL (end of list) ;1db1;00 opcode = TAG_L (tag list) ;db'JAPAN_SCENERY=';01 asciiz TAG_NAME=PATH\TO\SCENERY ;dbC:\FLTSIM5\JAPAN',0 TAG_LISTlabelbyte EOL

;FILE AND TYPE LIST (FS5.1) ******************************************** ;FILE & TYPE ENTITY OPCODE DEFINITIONS - ;OpFormatDefinition ;----------------------------------------------------------------- ;0db0;00 opcode = EOL (end of list) ;1db1;00 opcode = FILE_T (file & type) ;db0;01 scenery type ;; type = 10 = GLOBAL ;; = 20 = REGIONAL ;; = 30 = LOCAL_ ;; = 40 = ASD_LOW ;; = 50 = ASD_HIGH ;db1;02 flags ;; bit 0 = 0 -> inactive, 1 -> active ;; bit 1 = 0 -> not protected, 1 -> protected ;db'file path and name',0;03 asciiz file drv:/path/name.ext ;; drv: = a: z: = drive letters ;; = =: = fs51's drive ;; /path/ = /path = normal path ;; = /= = fs51's path

FILE_Tmacrodest,type,flags db1 dbtype dbflags dbdest,0 endm

FILE_TITLEmacrotitl dbtitl,0;Maximum title length 30 characters endm;(31 including trailing 00h)

GLOBAL= 10 REGIONAL= 20 LOCAL_= 30 ASD_LOW= 40 ASD_HIGH= 50 ;Flag masks INACTIVE= 0h;inactive ACTIVE= 1h;active PROTECTED= 2h;protected ;(can't delete, change destination, ;change type, make inactive, or ;change title)

FILE_AND_TYPE_LISTlabel word FILE_T'D:\NEW_YORK\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'New York Scenery' FILE_T'D:\DENVER\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'The Denver Area' FILE_T'D:\CHICAGO\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'Chicago Western Suburbs' FILE_T'D:\LOS_ANGLES\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'East LA' FILE_T'D:\DALLAS\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'Dallas Fort Worth' FILE_T'D:\LAS_VEGAS\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'Las Vegas Area' FILE_T'D:\SEATTLE\*.BGL',LOCAL_,INACTIVE FILE_TITLE 'Seattle & Redmond' FILE_T'D:\EPHRAIM\*.BGL',REGIONAL,INACTIVE FILE_TITLE 'Door County Wisconsin' FILE_T'D:\HAWAII\*.BGL',REGIONAL,ACTIVE FILE_TITLE 'HAWAII test database' FILE_T'D:\LONDON\*.BGL',REGIONAL,ACTIVE+PROTECTED FILE_TITLE 'LONDON test database' FILE_T'=:\=\*.BGL',REGIONAL,ACTIVE+PROTECTED FILE_TITLE 'FS5 Default World - Metro' FILE_T'=:\=\scenery\world\*.BGL',GLOBAL,ACTIVE+PROTECTED FILE_TITLE 'FS5 Default World' FILE_T'B:\SAVOY\*.BGL',REGIONAL,INACTIVE FILE_TITLE 'Small Savoy Database' EOL

;BOOSTER LIST (FS5.1) ************************************************** ;FILE & TYPE ENTITY OPCODE DEFINITIONS - ;OpFormatDefinition ;----------------------------------------------------------------- ;0db0;00 opcode = EOL (end of list) ;1db1;00 opcode = BOOSTER ;db1;01 1= booster active 0= inactive ;dw5000;02 cache size ;db1;04 cache cleanup mode ;;0=cleanup out of area & on exit ;;1=cleanup out of area only ;; 2=never clean up ;db2;05 cache update strategy ;;0=manual 1=semi auto 2=automatic ;db 'source filename',0;06 ;db'cache filename',0;nn

BOOSTERmacroactiv,cache_size,cleanup,updt,src,cache db1;;opcode dbactiv dwcache_size;;cache size in K dbcleanup;;cache cleanup mode dbupdt;;cache update strategy dbsrc,0 dbcache,0 endm

INACTV= 0;Booster active/inactive flag ACTIVE= 1 CLEANALL=0;clean cache on exit and leaving area CLEANAREA=1;clean cache when leaving area only NOCLEAN=2;do not clean up cache at all MANL=0;Cache update strategy SEMI=1 AUTO=2 BOOSTER_LISTlabel word BOOSTERINACTV,5000,CLEANALL,AUTO,'c:\cdrom\chicago','c:\chicago' BOOSTERINACTV,5000,CLEANALL,AUTO,'c:\cdrom\boston','c:\boston' BOOSTERINACTV,2000,NOCLEAN,MANL,'c:\cdrom\savoy','c:\savoy' BOOSTERINACTV,5000,CLEANALL,AUTO,'c:\lasvcd','c:\lasvegas' EOL

driver_endlabelword BGLSEGends end

The first byte in the preceding .vis file is the header, which begins by specifying the file length. Then, a 2-byte type ID is specified. These two bytes specify whether this file is a BGL or LOGOL file. In BGL, always include the code ‘MR’ in this field. Following the type ID are six pointers that point to the six data sections: title and description data, the world set ID list, the world sets, the file and type list, world set enhancements, and the booster list.

The title is a 30-ASCII character string that specifies the title of the world set. A zero terminates this string, and any unused characters should be padded by spaces. The total length of the string (with the terminating zero) is 31 bytes. In the example, strings such as “msgvis005” are taken from a message file that is language dependent.

The description is a 255-ASCII character string that is a description of the world set. A zero terminates this string, creating a total length of 256 bytes. In this example, the end of this string is automatically padded with zeros.

The Scenery Library dialog box uses the title and description data to identify the world set name and description to the user.

Every BGL file has a world set ID in its header. The WORLD_ID_LIST in this file is a list of all world set IDs that will be active. Any BGL file that matches one of these world set IDs is processed and displayed; any BGL file that has a world set ID that doesn't match is bypassed and not used. You can set the world set ID in your BGL files to 1 and ensure that they'll be processed and displayed. The following table includes the world set numbers and the "worlds" they define in Flight Simulator.

World set number	Description
0	File disabled
1	Default visual scenery
2	Crop duster world scenery
3	Default VORs and ADFs
4	Default ATIS and Landme
1000-1999	A&SD reserved

Flight Simulator 98 uses file specifiers in the .vis file to select files. As a result, world sets take on a somewhat different meaning. However, the world set file filter system works in the same way as in earlier versions of Flight Simulator.

In Flight Simulator 98, A&SD world set numbers have been reserved. A front-end filter is included that filters any files between 1000–1999 if asd_available=0. A&SD sets and clears asd_available by calling the FE_GET_MISC function with ax=2 and 3, respectively.

The file and type list specifies all the scenery sets and where they are located on the hard disk. Each scenery set entry contains the following:

Disk identifier: can be a drive specifier, such as D. Can be used to specify the Flight Simulator default drive (where Flight Simulator was installed).
Path: specifies a standard MS-DOS path in the format \New_York\*.Bgl. If you specify the path in this format, the front-end processor will assume that scenery files can be found in the New York directory. Can also be used to specify the Flight Simulator default directory.
Type: specifies global, regional, or local.
Title: specifies the ASCII title that identifies the scenery set in the Scenery Library dialog box.

The booster list is used in conjunction with CD scenery and booster processors. For more information, see the topic Using Booster Processors with the Scenery System.

Note: Throughout this SDK there are many references to the front-end processor. The front-end processor is a BGL system module that pulls in scenery data from all available sources and builds up a master list of scenery for the BGL graphics system to display. The specific tasks of the front-end processor are as follows:

Accessing all the data sources and building up a master object list (including seed objects) as quickly as possible.
Monitoring user movement through the Flight Simulator world and triggering rescans of the database when it’s determined that scenery may be visible.
Triggering rescans based on new scenery coming into data caches from CDs through the booster processors
Making the data access take place in the background and in a display frame interleaved manner to reduce or eliminate pauses in the graphics display.

Although the specifics that go into the process are complex, the front-end processor's basic function is straightforward: retrieve scenery from all sources and pass a master object list (including seed objects) to the BGL graphics system.