Sdl event loop

Sdl event loop. I have been stress testing SDL on Windows with a Razer Viper 8Khz, which is the first 8,000 hz polling rate mouse (most mice are 1,000 hz), and SDL_PumpEvents has poor performance. Before doing anything else, we get the start time for the loop, and only after all the work is done do we get the end time. I used to do this with SDL_GetKeyboardState(), but I switched over to using SDL_Event and SDL_PollEvent() to have a uniform interface for Keyboard, Mouse and Joystick input (everything done with events). Overview. SDL window does not open correctly. While loop going past limit. } I'm doing this tutorial about SDL in game development. If you need to remove a range of event types, use SDL_FlushEvents() instead. Vumaq, I think that in most cases, you do not need to use SDL_PumpEvent, as it is used by SDL internally. Try moving SDL_RenderPresent(Screen); outside of the while(SDL_PollEvent(&Ev)) loop. SDL2 event callback without polling. #define GLEW_STATIC #include <stdlib. This usually results in a floating window This will unconditionally remove any events from the queue that match type. Searching around the web, I've found that SDL2 allows for mouse trapping with the call to SDL_SetRelativeMouseMode(). h> #include <iostream> #include<conio. Pressing any key including I have got a small problem with my game. Oh wow okay, thats definitely gonna make things much more difficult, okay – asdfgodsia123 e890dik. This is because SDL_PumpEvents (which is called directly or indirectly by sdl) will not return until resizing is done, effectively blocking your thread. Ive also used the visual studio performance profiler to check, and sure enough, SDL_PollEvent is taking up ~94% of the cpu time. I have the typical/basic event loop for SDL2 and I'm a little confused on what to do with them or how to handle them or I guess more specifically how should I get the data from these events (e. It's also normal to just ignore events you don't care about in your event loop without You should be checking the return value of SDL_PollEvent. This system provides an alternative event loop in place of SDL2:WITH-EVENT-LOOP, with the following goals in mind: Be it easy to either handle all SDL_Event. Hit 10 keys and you will have your last input handled 10 frames later. Then we destroy the swapchain, and then we query the window size from SDL and create it again. youtube. The event queue itself is composed of a series of SDL_Event unions, one for each waiting event. I've written this code: bool open = true; while (open = true) { SDL_Event event; whi r = sdl_rect(50, 50, 150, 150) ! Create the renderer. Event system for c++. Don't declare ev as a pointer. type == SDL_QUIT, you have to use m_SDLEvent. while Statement breaking loop. perf_frequency = f64(SDL. What did I do wrong? 9. Right after the SDL event loop and the freeze_rendering check, add this before it also calls any NewFrame imgui functions. SDL 2 hangs when polling for events. Defined in <SDL3/SDL_events. However when I add the possibility for the character to shoot by pressing SPACE, I face a strange bug: If down and right keys or up and left keys are already pressed, no event is created when pressing SPACE. Remarks. C++ & SDL: SDL event repeats endlessly. SDL_MOUSEMOTION. Dispatch event in SDL. SDL_PumpEvents( ) Pump the event loop, gathering events from the input devices. Tip: If you are using the sdl2-starter project from Github, you’ll have already a sample code of how this initialization works. If state is set to SDL_QUERY, SDL_EventState will return the current processing state of the SDL keeps an event stack which is added to as your program runs. SDL crashes application? 0. typedef union SDL_Event {Uint32 type; /**< Event type, shared with all events, Uint32 to cover user events which are not in the SDL_EventType enumeration */ SDL_CommonEvent common; /**< Common event data */ SDL_ DisplayEvent display I want to create a little program, which should draw some Math Functions. SDL event loop quitting? 2. h and link the two together: #ifndef _CAPP_H_ #define I'm trying to develop a robust game input system with SDL 2. So my code looks like this: while(!Quit) { SDL_Event event; while(SDL_PollEvent(&event)) { //if-else statements that create //the games state machine //player input is received here //rendering done here Ive managed to narrow it down to SDL_PollEvent. type) { case SDL_MOUSEMOTION: { YCam += e. do while (sdl_poll_event(event) > 0) select case (event%type) case (SDL_QUITEVENT) exit end select end do ! Fill screen black. SDL2 not receiving window events. Instead, use a linear interpolation function to compute your position given the current time each time through the main loop. It's a queue. The basic idea, though, is that you simply set SDL_IGNORE or SDL_ENABLE depending on whether - move the qemu initialisations and I/O event loop on a new thread, and free the main thread exclusively for the SDL event loop (which can now block waiting for events) - keep the qemu initialisations and the I/O event loop on the main thread and schedule a timer every few milliseconds to poll if new graphical events are in the queue. At SDL build time, you need the libdecor-dev package. asked Apr 24, 2022 at 11:02. Currently all SDL events get blindly dispatched to the window polling the message loop. And declare SDL_Event e inside of the gameLoop method, and then pass it to another functions by value or by reference, it's always done like this in tutorials and books:. 5 on a Linux workstation (Red Hat Suppose you have an event manager. The program should leave the main loop when finding an input, but it does not: SDL_Window* gWindow = NULL; SDL_Surface* gScreenSurface = NULL; Game loop boils down to such pseudocode: let renderer = /*create renderer*/ var quit = false while !quit { quit = fetchEvents() updateState() render() SDL_RenderPresent(renderer) // if VSYNC is ON, it will block main thread } Without Vsync it is a busy loop, with Vsync it is a loop which constantly blocks main thread. Why does SDL window immediately close? 0. If you want 33 updates per second, then your constant timestep should be 1/33. The previous example may seem suspicious, as we’re providing SDL_PushEvent() a pointer to a local variable. And I think You should be checking event's in a while loop using polling which will pop the events from the queue as they are handled. pub fn is_event_enabled(&self, event_type: EventType) -> bool. event : SDL. h> #include <SDL_syswm. *) Header File Place the event-processing code of each thread in a critical section, so that the threads can wait for events asynchronously but process them synchronously; Choose one subsystem for the main event loop, and pass events from other subsystems via that subsystem as custom messages (for example, the Windows message loop and custom messages, or a SDL2 Playlist: https://www. SDL appears to "drop" the first event given to the event loop. 1. Essentially, SDL records input from What SDL_PollEvent does is take the most recent event from the event queue and puts the data from the event into the SDL_Event we passed into the function. source pub fn wait_event(&mut self) -> Event. Here is my processEvents If you move that outside of the SDL event loop, does that change anything? Reply reply I'm not sure if this is related because you mentioned you tried pulling controlPlayer out of the event loop already, but if there are multiple events in the event queue, you're potentially going to call controlPlayer multiple times per frame. Then the engine/game can query the state, and make changes to the Using functions like SDL_PollEvent and SDL_PeepEvents you can observe and handle waiting input events. So this will certainly cause a delay. It continues to run until the application quits. If there are no events, the loop will not iterate once. Inside of the SDL Event is an SDL Keyboard event which contains the information for the key event. Well, at first I used SDL_PollEvent(), which caused the 100% CPU use. It also shows you this warning WARNING: This should only be Description. 04. Follow edited Apr 24, 2022 at 16:02. *) Header File sdl; event-loop; Share. Improve this question. 2. And THIS while_loop is within another while_loop. This is my current code : All the include. Basic example: I am experimenting movements in a 2D game in SDL, and it works fine. Contribute to steven741/chez-sdl development by creating an account on GitHub. The terrible wiki documentation might be able to help get you up to speed. I got my inspiration from this answer, and it doesn't use additional threads. As such, we can remove the inner loop - we only need to call SDL_PumpEvents() once per frame. Add the following code after the call to Using the Event Loop. h> #include "SDL. h> Syntax. SDL event loop quitting? 4. 1)it uses a windows specific library,while SDL is multiplatform;2)SDL already provides its way to handle key events,and mixing that way is baaad;3)all keys terminate the loop, not only Esc (OP forgot his own "specification" in the question and this qualifies him as a not good asker);4)as general way is bad since it does not SDL event loop quitting? 0. SDL_PumpEvents calls into the operating system's event processing API and transforms platform events into SDL_Events, pushing them All we have to do is poll the SDL event system on each loop iteration to check if the user has pressed any buttons and if so to react appropriately. 100+ Code boost_asio¶ template <typename Executor> struct lager::with_boost_asio_event_loop¶. 137 1 1 silver badge 6 6 bronze badges. Instead the events should be dispatched to the window as provided by the event's window id or (if not set) to the window having focus. SDL window instantly closing. The SDL_Event structure is the core of all event handling in SDL. Note The Boost asio executor must be single threaded, since in general the store is not thread-safe context::dispatch() is thread safe, but it schedules the evaluation of actual store updates and effects in the event loop which, it assumes, evaluates Event Storage Duration. Waits indefinitely for the next available event. Source Code My SDL window is freezing IDK why I'm using PollEvent function. This will unconditionally remove any events from the queue that match type. We need to register an event, get the ID, and use it. So it adds up. Let’s create a function responsible for performing the SDL2 initialization. While Loop Terminating Unexpectedly (C/C++) 1. ) SDL_WindowEvent. SDL C++ Window Immediately Closes. SDL_PumpEvents gathers all the pending input information from devices and places it on the event queue. This may change in the future to I'm using SDL2 v2. 9-3, 64 bit, with VS2019 C++. Part of the course: Game Dev with SDL2. pub fn disable_event(&mut self, SDL window freezing with event loop . Here's how you can incorporate this into your code: # You can use SDL_WaitEvent(SDL_Event *event) to wait for an event in the SDL. rc = sdl_set_render_draw_color(renderer, uint8(0), uint8(0), uint8(0), uint8(SDL_ALPHA When we have a window event we then want to check the SDL_WindowEventID to see what type of event it is. It will use less resources than the polling loop design you currently have. Suppose you have an event manager. Using functions like SDL_PollEvent and SDL_PeepEvents you can observe and handle waiting input events. 28. SDL_QUIT events work with g++ but not gcc. Add the following lines after the window creation code: // Get an event SDL_Event event; SDL_PollEvent(&event); // Wait a bit SDL_Delay(3000); Use SDL_PeepEvent to fetch event, not SDL_PollEvent. type) { // exit if the window is closed case SDL_QUIT: game_state = 0; // set game state to done,(do what you want here) break; // check for keypresses case SDL_KEYDOWN: KEYS[event. void SDL_PumpEvents(void); Remarks. Typically, every iteration of the loop involves 3 steps: Process any events, such as user We use a while loop to process each event in turn. md for details */ SDL_APP_TERMINATING, /**< The application is being terminated by the OS Called on iOS in applicationWillTerminate() It seems you are experiencing the same issue, namely waiting for vsync in the middle of your event loop. Hot Network Questions DO-EVENTS performs the same polling/waiting code as SDL2:WITH-EVENT-LOOP but does not dispatch events to event handlers. Hey! I thought we would have a window stay up on screen! You lied to us! Woah! Before you start pelting me with tomatoes, I need you to remember something: You are supposed to call SDL_PollEvent in a loop, for example while(SDL_PollEvent(&e)) { /* handle events /* } because it only gives you a single event back. You're seeing garbage window ID because you access an inactive union field. The structure for all events in SDL. I'm using SDL 2. Remember, to add any of these components to our UI, we can construct them in our UI class, and add SDL_QUIT vs SDL_Quit() Using Attributes in the Event Loop. SDL event loop quitting? 8. SDL window not showing? 5. The returned values are consistent, but wrong, ALWAYS! I need advice on keyboard event handling with SDL. While loop ends prematurely. button. When the mouse is moved quickly In order to process mouse events in the main loop I'm checking for SDL_MOUSEMOTION. h> #define SIZE_MOVE_TIMER_ID 1 bool sizeMoveTimerRunning = Before the game loop starts, I initialize variables for my timestamps, any event, and the keyboard state. Everything else stays in the queue. quit structure, which has no field for window id (because SDL_QUIT is not I've mentioned this before in other game related threads. Commented Jan 21, 2021 at 8:34. The key to event handling in SDL is the SDL_Event union. renderer = sdl_create_renderer(window, -1, 0) ! Event loop. I don't want to render in real time. Normally, you handle events in a loop like this (copied from the documentation here):. Generating terrain doesn't freeze window, but when I'm trying to put generated terrain's surface (I don't have camera yet) into window, window freezes. While loop carries on forever (C++) 1. SDL2::events represents the library's version as three levels: major, minor, and patch level. The event buffer is large enough to always hold all queued events, so it's enough for testing Summary. h> #include <SDL2/SDL. SDL_PeepEvents -- Checks the event queue for messages and optionally returns them. Edit: Whoops - thought event was a pointer: The while (SDL_PollEvent(&event)) line will loop through until all pending events have been handled. SDL_ACTIVEEVENT equivalent in SDL 2. Often calls the need for SDL_PumpEvents is hidden from the user since SDL_PollEvent and SDL_WaitEvent implicitly Managing the Image Surface. g SDL_QUIT, SDL_WINDOWEVENT, SDL_KEYDOWN) to other areas of code. Toss an SDL_Delay(1) at the bottom, and you shouldn't have any issues. 6. It just looks like a lot since they are quite a bit of events. When any event occurs, like the mouse moving a few pixels, it gets added to the queue. In other cases, an event is created, as it should be. You have two options: Using SDL_Thread, but I prefere to not use threads when another solution is possible (because you may have to deal with semaphores or mutexes); Using SDL_TimerCallback (some would say that too much timers kill the flow of the code, but it's what we gonna use); Here is a code sample (NB: A thread-safe type that encapsulates SDL event-pumping functions. SDL2 was the previous version!) SDL_MouseButtonEvent. com/playlist?list=PLvv0ScY6vfd-p1gSnbQhY7vMe2rng0IL0 Find full courses on: Keep in mind that the SDL_Event is a union (all of the values share the same space as each other) and the reason that checking for SDL_KEYDOWN first works is because it's specifically looking for keyboard events and not anything that looks like a SDLK_ESCAPE key. Mouse Motion Events. The table below lists these relationships. Contribute to justengel/pyjoystick development by creating an account on GitHub. 2 on Ubuntu 12. 0. h> #include <math. Simulated action (like spinning) often takes multiple frames to complete, and for that time other actions should not be stopped - which is very difficult to do if your action is implemented in long blocking function. When I order to move to the left by pressing left arrow, it is processed by SDL_PollEvents() and responds correctly if the key was Internally, SDL stores all the events waiting to be handled in an event queue. h> #include <stdlib. Your application can register various handlers for various events with the event manager. SDL_PollEvent calls SDL_PumpEvents, removes the first event in the stack and copies it into the pointer given. SDL program immediately quitting after being started. Let’s update our Image class to make use of this. For m_controller. SDL_GetTicks() shouldn't be necessary, but if you want a fast fps estimate I'm programming things with SDL 1. At first a just wrote the code, that should create a little Window, that should just be visisble until I hit the X at the window. motion. SDL stands for Simple DirectMedia Layer, which is an open source library that provides APIs for user input, audio, and graphics. SDL_Event is a union of all event structures used in SDL. Methods impl EventPump. . I recommend this method as you can easily miss important events such as SDL_QUIT when using SDL_PeepEvent. A given integer was so big that its representation as a C integer would be negative. SDL_PumpEvents() gathers all the pending input information from devices and places it in the event queue. 0 keyboard input in pong-like game. Header File. The event queue SDL2-EVENT-LOOP. Event loop that relies on a Boost. See the example in this It will use less resources than the polling loop design you currently have. Pump the event loop, gathering events from the input devices. window if m_SDLEvent. Posted on July 30, 2022 — Updated September 4, 2024 The final application that will be built in this post. SDL_MOUSEMOTION and SDL_MouseMotionEvent are both related to mouse movement in SDL, but they serve different purposes in the event handling system. Description. My code (this is just main loop void SDL_FlushEvents(Uint32 minType, Uint32 maxType); DESCRIPTION¶ This will unconditionally remove any events from the queue that are in the range of minType to maxType, inclusive. With this call, though, the mouse is trapped and limited to move within the window, and not just at the center. Application using SDL exiting on any keypress. void function(SDL_Surface *screen) { SDL_Event event; bool quit=false; while (!quit) { SDL_WaitEvent(&event); switch (event. void InputMan::acceptInput(SDL_Event &e,Graphics * g){} and use it in your game loop like this: Description. h> #include "SceneOpenGL. *) Header File Description. These functions might be imported by name or with the :events tag. while(SDL_PollEvent(&test_event)) {The SDL_PollEvent function take a pointer to an SDL @IngoBlackman Yes, that would be great, like the way getchar(); returns when the character \n is input. Are no events being queued? 3. Does GLFW have an equivalent to the SDL_WaitEvent: SDL_Surface* screen; // do something with screen SDL_Flip(screen); SDL_Event event; while (SDL_WaitEvent(&event)) { // handle input } What do you put to figure out which buttons these are in the SDL_Event loop? I know they are usually known as button4 and button5 from assigning them in many games. Doing (sdl2:push-event :quit) twice terminates the program, but trying it with :my-quit only prints the data value, but does not quit the loop. Asio executor. motion: Description. I. Abhinay Singh Negi Abhinay Singh Negi. This function only affects currently queued events. Doing this will guarantee that no matter the hardware, space ships arrive at their destinations at the same time (though on a fast machine, you'll see more of the steps in between). That's undefined behavior. SDL_MOUSEMOTION is an event type constant used to identify mouse motion events. There are also mouse wheel events which weren't covered here, but if you look at the documentation and play around with it it shouldn't be too hard to figure out. Now, as you poll/pop all events there, act on what you can (like Window-related events), but store the inputs on a public (static) vector on your own I've cobbled together a very basic game loop in C++ using SDL2, and I've noticed that every few seconds, SDL_PollEvent seems to be unusually slow, even when nothing is happening. \n"); boycott = 0; return(0); if ( event->type == SDL_MOUSEMOTION ) {. SDL2 has a structure for handling window events such as moving a window or resizing a window. Most multimedia programs rely on an events system to process input. However, after several print statements showing that everything is working BUT my SDL_PollEvent() loop, I'm wondering if any events are being queued at all. Hot Network Questions How would you descirbe "context" in layman typedef enum SDL_EventType {SDL_FIRSTEVENT = 0, /**< Unused (do not remove) */ /* Application events */ SDL_QUIT = 0x100, /**< User-requested quit */ /* These application events have special meaning on iOS, see README-ios. md and README-android. *) Header File Python joystick event handler. SDL_PushEvent -- Pushes an event onto the event queue To poll events off the queue, use the SDL_PollEvent function. Query if an event type is enabled. SDL Events and Event Queues. h> #include <GL/glew. If you are expecting events to fire continuously, you can do something like: Uint32 timeout = SDL_GetTicks() + 10; while(SDL_PollEvent(&events) && !SDL_TICKS_PASSED(SDL_GetTicks(), timeout)) {} That will ensure that your event loop I'm working on a simple GUI, and i'm trying to use the SDL library with little success. md for details */ SDL_EVENT_TERMINATING, /**< The application is being Compile and run. h> Syntax Filtering and Handling Events. Start(); But this code is wrong in case of somebody else registering an event. Hot Network Questions the effect of Schengen visa refusal on Australian visa decision? Does it mean this ,suppose i want to execute 10 events inside this second while loop these events will be stored in event queue and corresponding frame is made and at the 11th event which is empty SDL_PollEvent() will return false and goes out of the second while loop and all the ten frame are rendered on the screen with SDL_RenderPresent() ,does it work like Remarks. The two most common event types for handling the keyboard are SDL_KEYDOWN, which is created when a button is pressed, and SDL_KEYUP, for when a the worst answer among all the others. The SDL_QUIT event occurs when the user closes our window, SDL_KEYDOWN occurs when a key is pressed and SDL_MOUSEBUTTONDOWN occurs if a mouse button is pressed. These are just a few of the wide variety of events that we can receive and I strongly recommend reading up about the other types in the SDL_Event documentation. window. h> #define WIN32_LEAN_AND_MEAN #define NOMINMAX #include <Windows. State outside of the event loop. SDL 2, how use the event system and draw asynchronously. It's also normal to just ignore events you don't care about in your event loop without calling this function. html, SDL stands for Simple DirectMedia Layer, which is an open source library that provides APIs for user input, audio, and graphics. Now that this has been all setup, let's jump over to CApp. WARNING: This should only be run in the thread that initialized the video subsystem, and for extra safety, you should consider only I know this is an older post, but I myself just came across this issue with SDL when starting up a little demo project. keysym. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company I'm trying to do a very basic main loop with SDL2 but the window opens and I can't close it. View Full Course Free, unlimited access. The macro is a DO-style loop with an implicit NIL block, which binds EVENT to an SDL event object (a single allocation that SDL_PumpEvents() and SDL_PollEvent() have a similar purpose, but are different in two key ways: SDL_PumpEvents() processes all the outstanding events on the queue, whilst SDL_PollEvent() only handles one event per invocation. These features make SDL a reasonable and popular choice for Understanding the SDL Event Loop. For example, if I were to check for quitting the game via the "x" box, and I click said "x" box in my application, nothing happens. If you need to remove a single event type, use SDL_FlushEvent () instead. SDL: Two Event Loops? 0. In any case it is not Swift concurrency friendly, The SDL uses an event queue internally. 0? 4. SDL Window does not show even with Event Loop. h" /* This function may run in a separate event thread */ int FilterEvents(const void keyboard() { // message processing loop SDL_Event event; while (SDL_PollEvent(&event)) { // check for messages switch (event. Like user 'thebuzzsaw' noted, the best solution is to use SDL_WaitEvent to reduce the CPU usage of your event loop. Now we need to call this function from the main run() loop when the image resizes. But then again, I think it wouldn't be so great, I think I rather constantly need to know whether if keys/buttons are pressed, and I think infinite loop handles it well, all it needs is a proper space for breathing. do ! Poll events. You would then capture the state outside of that and modify it based on SDL_MouseButtonEvent. In our main loop we’ll want to read in every event that’s occurred since the previous frame and handle them, we can do this by putting SDL_PollEvent in a while loop, since the function will return 1 if an event was SDL Event Loop. SDL_PushEvent -- Pushes an event onto the event queue That's why you use while(SDL_PollEvent()) loop to fetch event, process its contents, fetch next event, – keltar. And now it quickly pops up and vanishes. Often calls the need for SDL_PumpEvents is hidden from the user since SDL_PollEvent and SDL_WaitEvent If there are no immediate events on startup, you might not ever make it into that loop. When you call SDL_Init(), you likely do it from the main thread, and that's where your event queue is, so when you call SDL_PollEvent() from your timer thread, it won't have access to the internal SDL event queue, and thus will not return And this is intentional and expected, because SDL_PeepEvents is to copy all events from the queue to the local buffer (as one operation), and then the loop is to iterate over all return ones. As always, follow the suggestions by Glenn Fiedler in his Game Physics series. SDL provides a flexible API for processing input events. This course includes: 46 Lessons. My main event loop, copied from some obscure if ( (event->type == SDL_QUIT) && boycott ) {. Name SDL_WaitEvent -- Waits indefinitely for the next available event. Polls for currently pending events, and returns 1 if there are any pending events, or 0 if there are none available. So in the first example, I'm not flushing the event queue, so why I'm using the SDL2 C# wrapper through FNA and I need to be able to detect when the window resizes, min/maximizes, etc. while (SDL_PollEvent (&test_event)) { The SDL_PollEvent function take a pointer to an SDL_Event structure that is to be filled with event The application continuously produces frames, which may change in response to keyboard / mouse input or based on time. Sleep(30000); SDL_Event sdlevent = new SDL_Event(); sdlevent. Is that possible? Here is a little test program showing what I am trying to do. type) { case case SDL_QUIT: quit = true; break; } } This is working, but not well. SDL_PollEvent reference. It doesn't need to be inside that inner loop. (This is the documentation for SDL3, which is the current stable version. It shouldn't be though. The straightforward approach would be to use SDL_PollEvent to create an event loop - it calls SDL_PumpEvents under the hood. h> #include<dos. Add a comment | 1 Answer Sorted by: Reset to default 1 The window behavior sounds So looking at SDL documentation I found that SDL_PollEvent does call SDL_PumpEvents. This occurs even when I've stopped moving my mouse. When I comment out the event loop, the emulator runs super fast. Returns if the event type was enabled before the call. 0, this function does not put the application's process to sleep waiting for events; it polls for events in a loop internally. You can only access m_SDLEvent. h" /* This function may run in a separate event thread */ int FilterEvents(const Remarks. 8k 12 12 gold badges 89 89 silver badges 145 145 bronze badges. Many SDL2 application developers find such behaviour undesirable, so they typedef enum SDL_EventType {SDL_FIRSTEVENT = 0, /**< Unused (do not remove) */ /* Application events */ SDL_QUIT = 0x100, /**< User-requested quit */ /* These application events have special meaning on iOS, see README-ios. The I consulted the on-line documentation, and found SDL_WaitEvent(), but that mentions: Wiki wrote: As of SDL 2. Enable an event type. Here is a piece of my code for the event loop: /* Handle events on queue */ while(SDL_PollEvent(&e) != 0) { /* This print statement does not execute */ printf SDL_QUIT vs SDL_Quit() Using Attributes in the Event Loop. SDL event loop quitting? 1. QuitEvent’s memory location will be freed as soon as HandleLeftClick() ends, so it would seem possible that the event we receive in our main loop will be a dangling pointer. This causes the mouse to be able to move from This is the 5th devlog of Warmonger Dynasty, a 4X turn-based strategy game made in C++/SDL. We must retrieve a single event using SDL_PollEvent to get our window to appear before we wait. So I tried registering a user-defined event with an integer as data, but cannot get it to quit the event loop like :quit does. SDL2 was the previous version!) SDL_WindowEvent. We retrieve events from the operating system and then process them in our game loop. update(); } The basic idea, is to parse events, and store them as the state of the controller. Ive simplified my main loop and event loop so that they look similar to a simple SDL tutorial. You check for this event type in SDL_AddTimer is a problem here. typedef enum SDL_EventType {SDL_EVENT_FIRST = 0, /**< Unused (do not remove) */ /* Application events */ SDL_EVENT_QUIT = 0x100, /**< User-requested quit */ /* These application events have special meaning on iOS and Android, see README-ios. It also supports the most popular desktop and mobile operating systems — and even web browsers with WebAssembly — making it easier to write cross-platform code. If the application does not quit properly, the event loop will Martin Helmut Fieber GUI Development with C++, SDL2, and Dear ImGui. SDL_PollEvent will keep taking events off the queue until it is empty. So, a game loop can be divided into 3 parts: receiveInput() -- EventHandler class updateGamestate() -- Gamestate class render() -- Renderer class Since I'm working with SDL, the receiveInput() function for me is going to be an EventHandler class that will handle SDL events generated by user and network input. SDL_PollEvent causes screen to wake up after xset dpms force off. I want there to be no input lag at all. Keyboard Button Events. #include <stdio. SDL_WaitEvent -- Waits indefinitely for the next available event. SDL_PumpEvents reference. SDL uses libdecor to draw the window decorations on Wayland. View Full Lesson. while (1) { SDL_Event event; while (SDL_PollEvent(&event)) { // handle your event here } // do some other stuff here -- draw your app, etc. What we basically are doing is taking an SDL_Event pointer, and switching through the types, and then calling the appropriate function. Also, move SDL_BlitSurface(imgSurface, NULL, scrsurface, NULL); SDL_UpdateWindowSurface(window); somewhere else, as it will run after your program stops running, and all code after that will also run when run is set to 0. This function updates the event queue and internal input device state. When the user’s mouse is moved, an event with a type of SDL_MOUSEMOTION is created. Use either multiple if/then statements or a swicth block for handling the event. Your event manager would listen/poll for events, it then dispatch (call handlers to those that matches the event). 5 (from dnf package manager) When setting SDL_SetWindowResizable(window, SDL_FALSE); The window should become no longer resizeable. When our window gains or loses focus, SDL broadcasts an SDL_WINDOWEVENT. If state is set to SDL_IGNORE, that event type will be automatically dropped from the event queue and will not be filtered. We’ll add three things: An SDL_Surface* so we can remember what surface is associated with our Image object If you are using a single thread, setting up an event watcher using SDL_AddEventWatch is not enough. But what do I put in here to de Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company The canonical SDL event processing loop looks like this: while (SDL_PollEvent(&event)) { // Process event} Note that since you're relying on a single global 'event' variable for each update, fixing this will probably require making some revisions to your program structure. Our SDL_PollEvent(&Event) statement will update our Event object with any keyboard action that the user performs. This function allows you to set the state of processing certain event type's. We use a while loop to process each event in turn. (Verify SDL_WAYLAND_LIBDECOR is enabled at the end of CMake configuration) Wayland needs you to draw something before it creates a window. SDL supports keyboard, mouse, and joystick input as well as changing applications, To poll events off the queue, use the SDL_PollEvent function. I sent my deltaTi A type that encapsulates SDL event-pumping functions. Event loop should not perform any simulations, especially not SDL_Delay and alike. If your game doesn’t read input from the player, you don’t have much of a game. Using it is a simple matter of knowing which event type corresponds to which union member. Now we can move onto the SDL2 initialization, which is required in order to be able to initialize a SLD_Window. The This code is often called the application loop, main loop, or, if we’re making a game, the game loop. When writing a game from scratch, the first step is to write the game loop. void InputMan::acceptInput(SDL_Event e,Graphics * g){} or. Without calls to SDL_PumpEvents no events would ever be placed on the queue. Everythign was working fine until I made my Terrain generator class and function. An SDL_WINDOWEVENT_EXPOSED just means that window was obscured in some way and If the player left clicks this button, our main application loop will receive an SDL_QUIT event, triggering the loop to end and our program to quit. Here is our main loop. SDL_PollEvent returns events whose type field contains values that are incorrect. replace SDL_PollEvent(@Event) with SDL_PeepEvent(@Event, 1, SDL_GETEVENT, SDL_FIRSTEVENT, SDL_LASTEVENT). Behind the scenes, First off, we create an empty SDL_Event structure. Exit event loop in SDL. Consider this code (which uses the above event polling); #include <SDL2/SDL. h> #include <stdio. 51. It seems that SDL_Event has to be placed into a while loop to constantly check for events. Hot Network Questions Trumpet: I am having issues using my first valve The probability of one of three people getting the most balls from ten containers ranging from 1 to 10 How to describe a living room having a balcony door letting you view the city down below 64: 3 * sizeof (void *)];} SDL_Event; Remarks. yrel; } break; } When I run the program, nothing happens, however, once I first move the mouse, the SDL_MOUSEMOTION event keeps firing and the mouse keeps moving. What you want to do is to use a constant timestep which you get by accumulating time deltas. SDL_PollEvent() loop is not executing. h" #include <SDL2/SDL_image. Hot Network Questions SDL2::events - SDL Event Handling. Here's how it would look in your example for anyone looking for a quick solution to it in the future. Move the loop from out of your InputManager upward into your Game, call it Game::Loop or Game::ProcessEvents. Your current implementation will result in exactly what you describe, where the first object receives all of the input events SDL sends you. This event happens when ever you press a key on the keyboard. Depending on what button was pressed the destination rectangle that the owl image is rendered into is moved. This structure, SDL_WindowEvent, is useful because Windows's event loop for a window blocks the thread of execution that created the window when the window is being moved or resized. From what I've found it seems I should use the SDL_EventFilter delegate and SDL_WindowEventID enum. In the event loop, we handle the quit event and the events for all the buttons. Learn C++ and SDL development by creating hands on, practical projects inspired by classic retro games. printf("Quit event filtered out -- try again. Completing I've had similar; not a huge fan of how SDL does this but nothing stops you from storing the inputs in a secondary vector. key. Check return value of SDL_PollEvent and if it returns 0 - you'll have to call it again, as it means no event is popped from queue. Since modal resize events are added directly to the message queue by the operating system, and not dispatched by the user, they are not seen by the SDL event loop and therefore cannot be SDL_keysym typedef struct{ Uint8 scancode; SDLKey sym; SDLMod mod; Uint16 unicode; } SDL_keysym; The SDL_keysym structure describes a key press or a key release. 4. This works fine, but if I want a continuous input when the SDL 2 interface for chez-scheme. But if m_SDLEvent. The mod field describes the state of I'm having a problem with SDL 2. Within that event, the mouse’s x and y positions are available under Event. @dbc Since historically, a big problem with SDL documentation has been figuring out if the tutorial or other resource applies the version you are using, using a major release-specific tag of sdl-3 for a feature that will only be introduced in that major release is preferable in my view to using a generic tag of just sdl. The event loop is responsible for handling events, such as keyboard input and mouse movement. Your event manager would have a lookup mapping to keep track of all the handlers to corresponding event type. The mod field describes the state of Don't sleep. I'm developing in C language, and i can't switch to C++. So this is my input processing function: void MainGame::processInput() { SDL_Event evnt; while (SDL_PollEvent(&evnt)) { switch (evnt. source pub fn wait_event_timeout(&mut self, timeout: u32) When you run your while loop in each of your HandleInput functions, you're burning through the entire event queue up to that moment in time. At runtime, you need libdecor. If event is not NULL, the next event is removed from the queue and stored in that area. Pumps the event loop, gathering events from the input devices. I had a typical SDL event loop calling SDL_WaitEvent, and ran into a much-discussed issue (see here and here) where my application was not able to re-draw during a resize because SDL_WaitEvent doesn't return until a resize is finished on certain platforms (Win32 & Mac OS). We can also keep track of whether or not our window has focus using the event loop. SDL_PollEvent () is the favored way of receiving system events since it can be done from the main loop and does not suspend the main loop while waiting on an event to be posted. pub fn enable_event(&mut self, event_type: EventType) -> bool. type == SDL_WINDOWEVENT. Unlike the existing SDL2:WITH-EVENT-LOOP, nested dynamic invocations are not protected (RECURSIVE parameter). md for details */ SDL_APP_TERMINATING, /**< The application is being terminated by the OS Called on iOS in applicationWillTerminate() Basically, what you want to do is to achieve two things at a time. Events using SDL 2. Try moving close(); right after the end of the while (run) loop and before the // Blitting nad updating. GetPerformanceFrequency()) start : f64 end : f64. The outter while (!quit) would then keep your program open even if there are no events to process at the moment. #include <SDL. h> using namespace std; #ifdef WIN32 #include <GL/glew. SDL_PollEvent -- Polls for currently pending events. 0. SDL_PollEvent not responding to events. If state is set to SDL_ENABLE, that event type will be processed normally. SDL_AddTimer spawns a new thread, and things won't work like you expect when using multiple threads. To understand why the SDL window may not be closing, it is important to understand the SDL event loop. It is not a big deal but I'd love to sort this out. e. To workaround this, you can setup a callback in your event watcher: Table of Contents SDL_PumpEvents -- Pumps the event loop, gathering events from the input devices. I know this is an older post, but I myself just came across this issue with SDL when starting up a little demo project. The sym field is the SDLKey value of the key being pressed or released. The only argument it takes is a pointer to an SDL_Event structure which is basically an enum plus a union. SDL (C)- Window Won't Appear without Event Loop. To make your SDL window respond to close events, you need to modify your event handling loop to detect when the SDL_QUIT event is triggered, which occurs when the window's close button is clicked. OS: Fedora 39 Compositor: wl-roots (Hyprland) SDL version: 2. As you can see we handle closing the window as we did in the previous tutorial, then we handle an SDL_KEYDOWN event. type) { case SDL_QUIT: _gameState = GameState::EXIT; break; case SDL_MOUSEMOTION: break; case SDL_KEYDOWN: switch This is because the hook is currently only being called before message translation, from the SDL event loop, and not from the WndProc that actually handles the messages. However, this is not the case. You can either let Lux run an event loop (lux_loop), or you can run your own SDL event loop, But this loops through the body of the while loop until I stop it. SDL_Event The most effective way is to have some functions that are called for each event, whether that be mouse movement, mouse clicks, window resizes ect, and those should be handled in your main event loop by calling while (SDL_PollEvent(&event)) then have some if statements for each event and call the corresponding functions when those if statements are (This is the documentation for SDL3, which is the current stable version. And what SDL_PumpEvents does is to gather the state of all input devices to generate event objets. SDL_PollEvent () is the favored way of receiving system events since it can be done from the main loop and does not suspend the main loop while waiting on an event to be posted. If this is in a function like this, it quits only to the main(), so I need to click on "x" again to quit from the whole program. An SDL_WINDOWEVENT_SIZE_CHANGED is a resize event, so we get the new dimensions and refresh the image on the screen. When you poll for events (using SDL_PollEvent), you only get the oldest event. genpfault. h> #else The delay happens because flashingText() was called for every event polled, and the more mouse moves within the window, the more events are fired and polled by the loop. SYNOPSIS use SDL2 qw[:events]; DESCRIPTION. game. Often calls the need for SDL_PumpEvents is hidden from the user since SDL_PollEvent and SDL_WaitEvent implicitly SDL_Event e; SDL_PollEvent(&e); switch (e. We’ll then detect and react to those actions within the body of the loop. h> #include <iostream> int main() { SDL_Window* window; SDL_Renderer* renderer; // Initialize SDL. SDL_keysym typedef struct{ Uint8 scancode; SDLKey sym; SDLMod mod; Uint16 unicode; } SDL_keysym; The SDL_keysym structure describes a key press or a key release. An example implementing this can be seen and source-code downloaded below: [move_owl. SDL_PollEvents pops events from the stack until it is empty. Event state : [^]u8. event property to SDL_WINDOWEVENT_FOCUS_GAINED and SDL_PumpEvents. You probably want the SDL_EventState() function. type = SDL_USEREVENT; SDL_PushEvent(ref sdlevent); }). SDL Window Not Showing Up at all. Window state change event data (event. Lots of code, but all the SDL events should be covered. When the mouse is moved, SDL generates an event with this type. Mouse button event structure (event. By calling SDL_RenderPresent like that you are likely polling only 60 events per second (one per frame if vsync is enabled), causing the delay you see. WARNING: This should only be run in the thread that initialized the video subsystem, and for extra safety, you should consider only doing those things on the main thread in any case. Our SDL_PollEvent(&Event) statement will update our Event object with any mouse action that the user performs. It returns 1 if there is an event to handle, and 0 if there is not. I have a 1st person camera, and can walk fwd, back, strafe left and right and use the mouse to look around which is great. In past projects I tried dabbling with my own event system so I took the data from the SDL event So the immediate fix to send the event (BAD CODE ALERT): new Thread(() => { Thread. Commented Jan 21, 2021 at 8:40. SDL_Event test_event; SDL_PollEvent removes the next event from the event queue, if there are no events on the queue it returns 0 otherwise it returns 1. sym] = true; (This is the documentation for SDL3, which is the current stable version. The scancode field is hardware specific and should be ignored unless you know what your doing. How can . Since your code only polls once per second, the queue probably gets flooded by mouse movements, and the SDL_QUIT event SDL_Event. For any type of event that SDL sends to the queue and can be polled by the programmer there is a corresponding event structure that is placed in the union of SDL_Event. To determine whether the event was caused by a window gaining or losing input focus, we can compare the Event. printf("Mouse moved to SDL_PumpEvents -- Pumps the event loop, gathering events from the input devices. So yes, whichever event handler you call first will eat all of the events. These features make SDL a reasonable and popular choice for Filtering and Handling Events. The F-keys can be used as global hotkeys. Your game loop doesn't follow the traditional pattern of polling for input, updating your objects, and finally rendering them. Functions. If you want to read the previous entries, take a look at my reading list. Summary. It looks like SDL_PumpEvent does the work of querying the input devices, building the SDL_event structures, and placing them on the queue that is SDL_PumpEvents -- Pumps the event loop, gathering events from the input devices. Pushing Events and Custom Event Types. SDL mouse events are not being handled quick enough. This question is old, but the solution I'm using doesn't seem to be mentioned anywhere else, so here it is. In each of these discussions, the technique of using SDL_SetEventFilter to get (This is the legacy documentation for SDL2, the previous stable version; SDL3 is the current stable version. Really high Windows have a number of event-handling functions starting with on_, which you use to override window behavior. I've tried attaching such an event using SDL_AddEventWatch and SDL_SetEventFilter methods, but I'm not getting any events Here is our event loop. The SDL_LoadBMP() function creates an SDL_Surface using the dimensions and colors of the file we loaded, and it returns a SDL_Surface* - that is, a pointer to the surface. 1. I am fairly sure that it is not a stack, but a queue. Checkout the docs. In the rendering section, all the buttons are rendered to the screen. The The Event Loop. tsjeixhz unrs somai yibzv qoj uvyx kirvh iypfl jxqod jcbsxx