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Terminating a GLUT loop inside a program


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#1 some_math_guy   Members   -  Reputation: 122

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Posted 16 February 2006 - 08:30 AM

Is it possible to terminate a GLUT loop without terminating the entire program? I'm trying to write a program that can do some calculations, pop open a window and draw a simulation using GLUT to visualize the sim using the calculations, , then terminate the window and output some results to a datafile. The above will actually run in a loop that will run many times, but so far I haven't found a way to break out of the GLUT loop without exiting the program completely. What I am working on is running a genetic algorithm to help me find optimal parameters for the simulation. The way I have set it up, the GA loop is doing the selection and crossover/mutation to come up with parameters, then the GLUT loop uses these parameters to run the simulation. Once the simulation has run for a given time period, some measurements are outputted to a datafile and the window is terminated. These results are then fed back into the GA loop to update the population (hopefully improving over time). something like while(stopping_criteria_not_met) { Select_parameters_from_population(); // run the entire simulation, then terminate Open_GLUT_window(); Record_fitness_results_from_simulation(); } Is there a way to jump out of the glutMainLoop() without terminating execution of the program, or is there perhaps a better way to set up the structure of my loop using GLUT (ie. the GA running inside the GLUT loop)? Kevin

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#2 Brother Bob   Moderators   -  Reputation: 8088

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Posted 16 February 2006 - 09:12 AM

GLUT does not allow you to exit the main loop, and that was by design if I remember correct but don't ask me for exact reason though. It's just designed to be a framework for lightweight tech demos and such; you run it and close it when done, and that's it.

#3 T2k   Members   -  Reputation: 220

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Posted 16 February 2006 - 11:08 AM

no there is no way to leave the glut loop in a normal way. However you can do various things. First i list the ones you should try to not use:
-you could jump out of it with 'setjmp', but it could actually cause more damage than you think, especially when you jump right away before glut frees its resources
-or you could use '_onexit' for a function that will be autmatically called when your app exits. However that function cant take any arguments and will therefore have to access your data through globals it will also force you to exit and restart the app many times
Now you can do a third method, that is multithreading, your app (main) communicates with your glut-render-thread through some sort of message system. Then your OpenGlutWindow function would send a message that indicates it to display itself and hide again when the user 'closes' it (but it wont close for real, instead hide itself and send your main app a message to continue processing)...


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#4 sheepsteak   Members   -  Reputation: 122

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Posted 17 February 2006 - 04:02 AM

I've battled with this problem before and thought you might like to know about FreeGLUT. The original GLUT is quite old now and hasn't been updated since 1998. FreeGLUT also has options for leaving the main loop as stated here in the API documentation. Its virtually identical syntax to GLUT I'm led to believe but I've never tried it myself.

#5 RobTheBloke   Crossbones+   -  Reputation: 2339

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Posted 17 February 2006 - 04:47 AM

Quote:
Original post by sheepsteak
I've battled with this problem before and thought you might like to know about FreeGLUT. The original GLUT is quite old now and hasn't been updated since 1998. FreeGLUT also has options for leaving the main loop as stated here in the API documentation. Its virtually identical syntax to GLUT I'm led to believe but I've never tried it myself.


it is glut with extensions. Takes slighly longer to start a free glut app than one based on the original glut, but it's pretty good.


#6 sheepsteak   Members   -  Reputation: 122

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Posted 17 February 2006 - 07:02 AM

I thought it sounded too good to be true. [embarrass]

#7 AxoDosS   Members   -  Reputation: 284

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Posted 18 February 2006 - 09:09 PM

Here is one way of doing it:

void myIdleFunc()
{
...
if (should_we_exit)
{
throw "MY_EXIT_MESSAGE";
}
}

int main()
{
try
{
...
glutMainLoop();
}
catch (const char* msg)
{
...
}

cleanup();
printf("program terminated\n");

return EXIT_SUCCESS;
}







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