[SOLVED] Access AppSystemLogic variable from WorldLogic

[matthew.clifton]

Hi all,

I'm trying to access a public variable I have created within AppSystemLogic.h. I have various different AppWorldlogic classes. I've been following the processes for sharing Member Variables from https://developer.unigine.com/en/docs/2.7.2/code/usage/sharing_data/index but I'm struggling to get it to compile.

I think the problem seems to come from trying to create a pointer to AppSystemLogic within my new WorldLogic class as there is already a pointer in AppWorldLogic.h

There are only a few lines of code within each header, but it would be quite a block of text to paste them all here. I've zipped them up if someone would have a moment to scan over them?

Source:
https://we.tl/t-HSW9e3yMd7

I'm trying to access the 'test_var' in PlanettestWorldLogic::init()

I can't thank you enough in advance,
Matt.

[fox]

Hi Matt,

Maybe it's easier to use a global variable in this case instead of an AppSystemLogic class member.

This should solve your problem.

Thank you!

 

[matthew.clifton]

Thank you for your reply Fox

That is a shame I have to go down the route of a global variable class. There isn't a way of having the shared variables within the AppSystemLogic? I guess ultimately the final goal is the same, it just seems cleaner to have them within the persisting AppSystemLogic.

Kind Regards,
Matt.

[matthew.clifton]

Hi again @fox... just thinking a bit more about this. Surely i'm going to need access to the AppSystemLogic object to handle the loading of Worlds?

Apologies if this is derailing the thread a bit, but it all stems from my inability to access AppSystemLogic from derived WorldLogic classes.

Any thoughts on this?

Best Regards,
Matt.

 

[fox]

Hi Matt,

Sorry for the delay. No problem, if you want to use a member variable of the AppSystemLogic class. You can put everything related to changing world logics to the AppWorldLogic.

// AppWorldLogic.h

#include <UnigineLogic.h>
#include <UnigineStreams.h>
#include "AppWorldLogic1.h"		//<-- include world logic class declaration for the first world
#include "AppWorldLogic2.h"		//<-- include world logic class declaration for the first world
class AppWorldLogic : public Unigine::WorldLogic {
	
public:
	//...

	Unigine::WorldLogic *current_world_logic = &wl1;	//<-- pointer to the current world logic
	AppWorldLogic1 wl1;							//<-- world logic for the first world
	AppWorldLogic2 wl2;							//<-- world logic for the second world
};

#endif // __APP_WORLD_LOGIC_H__

Inside each method of the AppWorldLogic class we simply call the corresponding method of the current world logic class. In the init() method, as it is called each time a new world is loaded, we also should change the current world logic if necessary:

// AppWorldLogic.cpp
#include <UnigineWorld.h>

// ...
int AppWorldLogic::init()
{
	// checking the name of the loaded world and updating current world logic
	if (strcmp(World::get()->getName(), "world1") == 0)
		current_world_logic = &wl1;
	else if (strcmp(World::get()->getName(), "world2") == 0)
		current_world_logic = &wl2;

	// calling init method of the current world
	current_world_logic->init();
	
	return 1;
}

// ...

In this case we'll have just world loading operations in the AppSystemLogic.

// AppSystemLogic.cpp
#include <UnigineApp.h>
#include <UnigineWorld.h>
// ...
int AppSystemLogic::update()
{
	// checking key states and loading worlds
	if (App::get()->clearKeyState(App::KEY_PGUP))
	{	// loading the second world if it is not already loaded
		if (strcmp(World::get()->getName(), "world2") != 0)
			World::get()->loadWorld("world2");
	}
	else if (App::get()->clearKeyState(App::KEY_PGDOWN))
	{	// loading the first world if it is not already loaded
		if (strcmp(World::get()->getName(), "world1") != 0)
			World::get()->loadWorld("world1");
	}
	
	return 1;
}

// ...

Then you can add your member variable:

// AppSystemLogic.h

// ...

class AppSystemLogic : public Unigine::SystemLogic {
	
public:

// ...

	int member_var = 1;// <-- member variable
	
};

Include the AppSystemLogic.h and add a pointer to the AppSystemLogic to each of your derived classes and use your member variable:

// WorldLogic1.h
// ...
#include "AppSystemLogic.h"		//<-- header file for the  AppSystemLogic class


class AppWorldLogic1 :
	public Unigine::WorldLogic
{
public:
 	// ...
	
	AppSystemLogic *system_logic;// <-- pointer to the AppSystemLogic instance
};

// ---------------------------------------------

// WorldLogic1.cpp
// ...
int AppWorldLogic1::init()
{
	Log::message("This is WORLD 1 named\n");
	Log::message("The value of the member variable is %d\n", system_logic->member_var);// <-- print the value of the member variable
	system_logic->member_var = 111;	// <-- modify the value of the member variable

  	return 1;
}

And the last thing to do is to link instances of your derived classes with the AppSystemLogic instance in main():

// <your_project_name>.cpp

// ...

int main(int argc, char *argv[])
#endif
{
	// init engine
	Unigine::EnginePtr engine(UNIGINE_VERSION, argc, argv);

	// UnigineLogic
	AppSystemLogic system_logic;
	AppWorldLogic world_logic;
	world_logic.wl1.system_logic = &system_logic;	//<-- linking WL1 with the AppSystemLogic instance
	world_logic.wl2.system_logic = &system_logic;	//<-- linking WL2 with the AppSystemLogic instance
	AppEditorLogic editor_logic;
	
	
	// enter main loop
	engine->main(&system_logic, &world_logic, &editor_logic);
	
	
	return 0;
}
// ...

Hope this helps!

Thank You!

[matthew.clifton]

Thank you so much....  this worked perfectly!

Best regards,
Matt.