Warning! This version of documentation is OUTDATED, as it describes an older SDK version! Please switch to the documentation for the latest SDK version.
Callbacks
Any function from system, world or editor scripts can be called in a C++ code. UnigineScript functions that are called from an external code are known as callbacks. Via callbacks scripts can communicate with each other, as well as with the external application.
- Callbacks support up to 4 arguments and can return a value of an arbitrary type.
See also
An example can be found in <UnigineSDK>/source/samples/Api/Scripts/Callbacks/ directory.
Callbacks Usage Example
C++ Side
To demonstrate how callbacks can be used, let's code the C++ part first:
Source code
(C++)
#include <UnigineEngine.h>
#include <UnigineInterpreter.h>
using namespace Unigine;
/******************************************************************************\
*
* World function
*
\******************************************************************************/
/*
*/
const Variable &runWorldFunction(const Variable &name,const Variable &v) {
Log::warning("runWorldFunction(%s,%s) is called\n",name.getTypeName().get(),v.getTypeName().get());
Engine *engine = Engine::get();
return engine->runWorldFunction(name,v);
}
/******************************************************************************\
*
* Main
*
\******************************************************************************/
/*
*/
int main(int argc,char **argv) {
// export the runWorldFunction() function defined above
Interpreter::addExternFunction("runWorldFunction",MakeExternFunction(&runWorldFunction));
// initialize the engine
Engine *engine = Engine::init(UNIGINE_VERSION,argc,argv);
// start the main loop
while(engine->isDone() == 0) {
engine->update();
engine->render();
engine->swap();
// call the counter() function of the script (defined below)
Variable ret = engine->runWorldFunction(Variable("counter"));
// print a message depending on the value returned by the counter() script function:
// print the current value of the counter
if(ret.getInt() != -1) Log::message("counter is: %d\n",ret.getInt());
// print the world name
if(ret.getInt() == 3) Log::message("\nworld name is: \"%s\"\n",engine->runWorldFunction(Variable("engine.world.getName")).getString());
}
// shut down the engine and call the shutdown() function in the loaded world script
Engine::shutdown();
return 0;
}
Unigine Script Side
And now the UnigineScript side where callbacks are defined:
Source code
(UnigineScript)
// my_world.cpp
/*
*/
int callback(int value) {
log.warning("callback(%s) is called\n",typeinfo(value));
return value;
}
/*
*/
void counter() {
for(int i = 0; i < 4; i++) {
log.warning("counter(): called\n");
yield i;
}
return -1;
}
/*
*/
int init() {
log.message("\n");
// run the callback() script function via the API runWorldFunction() function
log.message("result is: %s\n\n",typeinfo(runWorldFunction("callback",10)));
log.message("result is: %s\n\n",typeinfo(runWorldFunction("callback",vec3(1,2,3))));
log.message("result is: %s\n\n",typeinfo(runWorldFunction("callback","a string")));
/////////////////////////////////
// show a console
engine.console.setActivity(1);
return 1;
}
Calling Sequence
The sequence of function call will be as follows:
- The interpreter exports the runWorldFunction() function to make it available from the script.
- The engine is initialized, and the init() function of the script is called. This function calls the exported runWorldFunction() function.
- The exported runWorldFunction() function calls the callback() function from the script.
- The engine enters the main loop, where it calls the counter() function from the script by using the Unigine::Engine::runWorldFunction() function.
Output
The following result will be printed into the console:
Output
runWorldFunction(string,int): called callback(int: 10): called result is: int: 10 runWorldFunction(string,vec3): called callback(vec3: 1 2 3): called result is: vec3: 1 2 3 runWorldFunction(string,string): called callback(string: "a string") is called result is: string: "a string" counter(): called counter is: 0 counter(): called counter is: 1 counter(): called counter is: 2 counter(): called counter is: 3 world name is: "data/callbacks"
Last update: 2017-07-03
Help improve this article
Was this article helpful?
(or select a word/phrase and press Ctrl+Enter)
