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General / event-driven rendering (instead of rendering at each main loop iteration)?
« on: November 12, 2012, 08:40:32 pm »
Hi
the examples i tried work nicely, but they hog the CPU because the window is re-drawn at every iteration of the main loop. While this is certainly what you'd want for an action game that has to re-render constantly as fast as possible because every frame is different, it's not what you'd want for an event-driven application where the rendering content only rarely changes (e.g. a drawing program or actually most type of non-game application software that doesn't show animations). So i tried to change the event processing so as to only redraw the window when either of these happens:
* resize
* exposure (even partial; e.g.: some other window is dragged over my window and hides a part of it during this process. Each obstructed part of my window has to be redrawn when the other window isn't hiding it any more)
* reactions to user interaction (e.g. ui elements changing appearance because of a click on an active region)
My problem:
When i look at sf::Event::EventType, i do see sf::Event::Resized but no event type that would correspond to an Expose Event. Is there something i'm missing there? I don't see how to develop an event-driven main loop (i.e. one that does not constantly re-render even if nothing happens) without an expose event. So how would you guys do it?
Is there some example somewhere that would use sfml like that?
the examples i tried work nicely, but they hog the CPU because the window is re-drawn at every iteration of the main loop. While this is certainly what you'd want for an action game that has to re-render constantly as fast as possible because every frame is different, it's not what you'd want for an event-driven application where the rendering content only rarely changes (e.g. a drawing program or actually most type of non-game application software that doesn't show animations). So i tried to change the event processing so as to only redraw the window when either of these happens:
* resize
* exposure (even partial; e.g.: some other window is dragged over my window and hides a part of it during this process. Each obstructed part of my window has to be redrawn when the other window isn't hiding it any more)
* reactions to user interaction (e.g. ui elements changing appearance because of a click on an active region)
My problem:
When i look at sf::Event::EventType, i do see sf::Event::Resized but no event type that would correspond to an Expose Event. Is there something i'm missing there? I don't see how to develop an event-driven main loop (i.e. one that does not constantly re-render even if nothing happens) without an expose event. So how would you guys do it?
Is there some example somewhere that would use sfml like that?