Using Booster Processors with the Scenery System

Compact discs have the capacity to store a large amount of scenery, but that access time is excessive; that is, performance is degraded to an unacceptable level. But, you can solve this problem by using scenery caches. Scenery caches are scenery sets on hard disk that are copied from a compact disc and then used as ordinary hard disk–based scenery. The following example shows scenery caches for the United States, Africa, and Europe.

C:\USACachScenery
g001001.bgl
g007003.bgl
f001127.bgl
Texture
g001001.txr
f001002.txr
C:\AfricaCachScenery
g001001.bgl
g007003.bgl
f001127.bgl
Texture
g001001.txr
f001002.txr
C:\EuroCachScenery
g001001.bgl
g007003.bgl
f001127.bgl
Texture
g001001.txr
f001002.txr

Note: The scenery caches in the preceding example are located on the hard drive (drive C). Each cache is structured in the same way as any other scenery set; that is, each scenery area includes Scenery and Texture directories in which the .bgl and texture files reside, respectively.

Putting compact disc scenery onto the hard disk boosts the performance of the compact disc scenery, but it also necessitates a system that creates and controls these caches. Creating and controlling these caches is the purpose of booster processors. Booster processors are small programs that run in the background (between display frames) and both set up and feed data to the scenery caches. You can use booster processors for the following tasks:

• Selectively copy files, real-time, from a large database (for example, 100 MB) into a much smaller disk cache (5 MB) based on proximity to the objects in the scenery and desired resolution.
  
  
• Create, clean up, and remove caches for scenery as needed (real-time) based on user preferences concerning run-time disk usage and disk space savings when Flight Simulator isn't running.
  
  
• Control re-triggering of the BGL data scan (in the front-end processor) to load new scenery that the booster processor has loaded or remove old scenery that has been eliminated.
  
  
• Format data from a more sophisticated scenery grid structure on the compact disc to the standard directory and file structure in the cache on the hard disk.
  
  
• Manage compact disc swapping. This way, compact disc caches for multiple scenery compact discs can be filled and managed simultaneously. As information is needed from a particular compact disc, the user can be prompted to insert that compact disc in the CD-ROM drive.

The following example shows a snapshot of a Flight Simulator system directory structure; in this example, the Flight Simulator directory structure is running on drive C and the CD-ROM scenery disc is running on drive E.

C:\FltSim5(Flight Simulator, version 5.1 executable tree, installed from compact disc when product installed.)
E:\FS1CD(CD-ROM disc, Flight Simulator, version 5.1, compact disc version.)
C:\USACach(Cache directory set up by booster processor included on Flight Simulator, version 5.1, compact disc.)

C:\FltSim5\Situation
Setup.exeVideos
Setup.ovlAircraft
Readme.docPilots
Fssystem.exeScenery
Panels
Texture
Sound
FS5World\Scenery
Texture

E:\FS51CD(Note: This directory isn't used at run-time; it's used to install the Flight Simulator,

version 5.1 compact disc.)
Setup.exe
Setup.ovl
Readme.doc
Disk1cd.exe
Fssystem.exe
USA\Scenery\Grid001
boosterg001001.bgl
bstinfo\Grid002
\Files001
f001001.bgl
\Files002
\Texture\Grid001
   g001007.txr
\Grid002
\Files001
\Europe\Scenery\Grid001
booster\Grid002
bstinfo\Files001
\Files002
\Texture\Grid001
\Grid002
\Files001
\Africa\Scenery\Grid001
booster\Grid002
bstinfo\Files001
\Files002
\Texture\Grid001
\Grid002
\Files001
C:\USACach\Scenery
booster g001001.bgl
bstinfo g007003.bgl
f001127.bgl
\Texture
g001001.txr
f001002.txr
C:\AfricaCach\Scenery
booster g001001.bgl
bstinfo g007003.bgl
f001127.bgl
\Texture
g001001.txr
f001002.txr
C:\EuroCach\Scenery
booster g001001.bgl
bstinfo g007003.bgl
f001127.bgl
\Texture
g001001.txr
f001002.txr
As shown in the preceding example, the file structure on the compact disc is slightly different than the file structure of a standard Flight Simulator installation. For example, the Grid and Files directories are located in the Scenery and Texture directories; you'll also find the .bgl and .txr files in this location. The differences in file structure are part of the more advanced storage scheme used in compact disc scenery; scenery is arranged in a grid pattern, and the booster processor interprets user location to determine which scenery grid to load data from. Then, the data is loaded into the cache on the hard disk.

Another difference is that, with the compact disc installation, the booster and Bstinfo files actually exist within the file structure. The booster file is the executable booster processor itself, and the Bstinfo file contains information about the scenery disk structure, its geographic bounds, and other important information. For more information on these files, see the topic Bstinfo Files and the Specifics of Booster Operation.