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Howto:Add new fgcommands to FlightGear: Difference between revisions
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Howto:Add new fgcommands to FlightGear (view source)
Revision as of 11:41, 12 March 2015
, 12 March 2015→Reaching out to subsystems: https://gitorious.org/fg/flightgear/commit/b21bb90ae57864c6bc565ae480036f3c11f7efe6#comment_110790
m (→Reaching out to subsystems: https://gitorious.org/fg/flightgear/commit/b21bb90ae57864c6bc565ae480036f3c11f7efe6#comment_110790) |
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Quite possibly, you may need to reach out to some other subsystems to implement a certain fgcommand, such as accessing the sound system, the networking system or the FDM system, this is accomplished by using the globals-> pointer, which allows you to access other subsystems easily. Please refer to [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.cxx#line120 $FG_SRC/Main/globals.cxx] and its header file [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.hxx globals.hxx]. A number of helpful usage examples can be found by searching fg_commands.cxx for "globals->". | Quite possibly, you may need to reach out to some other subsystems to implement a certain fgcommand, such as accessing the sound system, the networking system or the FDM system, this is accomplished by using the globals-> pointer, which allows you to access other subsystems easily. Please refer to [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.cxx#line120 $FG_SRC/Main/globals.cxx] and its header file [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.hxx globals.hxx]. A number of helpful usage examples can be found by searching fg_commands.cxx for "globals->". | ||
In general, you will always want to add a NULL pointer check to ensure that the corresponding subsystem handle could actually be retrieved: | |||
<syntaxhighlight lang="cpp"> | |||
FGMultiplayMgr * self = (FGMultiplayMgr*) globals->get_subsystem("mp"); | |||
if (!self) { | |||
SG_LOG(SG_NETWORK, SG_WARN, "Multiplayer subsystem not available."); | |||
return false; | |||
} | |||
</syntaxhighlight> | |||
Equally, it may be appropriate to wrap code in between try/catch blocks, too. | |||
A list of methods available to access certain subsystems is provided here in [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.hxx#line220 globals.hxx, beginning in line 220]. | A list of methods available to access certain subsystems is provided here in [http://gitorious.org/fg/flightgear/blobs/next/src/Main/globals.hxx#line220 globals.hxx, beginning in line 220]. | ||