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OpenGL [Noob] Going from Glut / OpenGL to SDL / OpenGL

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Hi, i am currently learning OpenGL. I started out using Glut to handle input in which you set up callbacks at the begining for the events and the rendering. But later on i saw and was told than Glut was rather limited and SDL was a better solution for game because it implements at least image loading, input, 2D rendering and sound capabilities. But now i am facing a rather annoying problem. I want to seperate rendering and handling of events and even game logic. In Glut this was easy by setting up callbacks. But in SDL i saw that neither the event handling nor the rendering were thread safe. So my question is, how am i supposed to wait for events (which blocks the thread), render graphics at a decent frame rate and implement game ticks ( like a game function called every 50 ms or so independent from rendering ). Thanks alot for your time!

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I have this inside my game loop...it doesn't hurt the frame rate at all.


while( SDL_PollEvent( &event ) )
{
// Handel the event
}

// Do drawing

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Thanks, that seems fine if i only handle events and render images but what about if i want a game tick mechanism (i dont want the game speed to depend on the cpu).

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ok maybe i was a bit stupid. I only need to render the frames if some event occurs so i can do:

main loop:
PollEvent
if( enough time went by )
game tick
render

right now im doing

main loop:
PollEvent
render

and a seperate SDL Thread for gameticks containing a loop and
a SDL_Delay mechanism to trigger itself regularly.

But is using PollEvent good? It eats up alot of cpu.

My game thread is something like that:

int gameTicks( void *Game )
{
Uint32 tick_delay = 30; //tick interval in milliseconds
Uint32 start_time, current_time, elapsed_time;

while( !game_end )
{
start_time = SDL_GetTicks();

if( !game_pause )
//do stuff with Game

current_time = SDL_GetTicks();
elapsed_time = current_time - start_time;
if( elapsed_time < tick_delay )
{
SDL_Delay( tick_delay - elapsed_time );
}
}
return 0;
}

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Well finally i did it all in the main thread using SDL_PollEvent and SDL_GetTicks to control the frames per second and ticks per second.

I know this has really little to do with OpenGL now.

Anyways, heres the main loop code, i think its fine like that but if anyone has general suggestions about how to make a good main loop go on ( im trying to make a small rts btw, i already did a small one in SDL and im trying to do another small one but in 3D now ).


Uint32 fps_desired = 100;
Uint32 fps_tick_delay = 1000/fps_desired;
Uint32 fps_start_time, fps_current_time, fps_elapsed_time;

Uint32 tps_desired = 30;
Uint32 tps_tick_delay = 1000/tps_desired;
Uint32 tps_start_time, tps_current_time, tps_elapsed_time;

tps_start_time = fps_start_time = SDL_GetTicks();

SDL_Event *event = new SDL_Event();
while ( !game_end )
{
/**handle events*/
while( SDL_PollEvent(event) )
{
handleEvent(event, game);
}

/**handle game ticks with tick per seconds contorl*/
tps_current_time = SDL_GetTicks();
tps_elapsed_time = tps_current_time - tps_start_time;
if( tps_elapsed_time >= tps_tick_delay )
{
tps_start_time = SDL_GetTicks();
if( !game_pause )
{
gameTick(game);

}
}

/**handle rendering with frames per second control*/
fps_current_time = SDL_GetTicks();
fps_elapsed_time = fps_current_time - fps_start_time;
if( fps_elapsed_time >= fps_tick_delay )
{
fps_start_time = SDL_GetTicks();
renderScene(game);
}
}

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