diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index 85621449aa..799eda79bf 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -140,6 +140,7 @@ add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playbac add_sdl_example_executable(audio-simple-playback-callback SOURCES audio/02-simple-playback-callback/simple-playback-callback.c) add_sdl_example_executable(audio-load-wav SOURCES audio/03-load-wav/load-wav.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.wav) add_sdl_example_executable(audio-multiple-streams SOURCES audio/04-multiple-streams/multiple-streams.c) +add_sdl_example_executable(input-joystick-polling SOURCES input/01-joystick-polling/joystick-polling.c) add_sdl_example_executable(camera-read-and-draw SOURCES camera/01-read-and-draw/read-and-draw.c) add_sdl_example_executable(pen-drawing-lines SOURCES pen/01-drawing-lines/drawing-lines.c) add_sdl_example_executable(demo-snake SOURCES demo/01-snake/snake.c) diff --git a/examples/input/01-joystick-polling/README.txt b/examples/input/01-joystick-polling/README.txt new file mode 100644 index 0000000000..89e2bee028 --- /dev/null +++ b/examples/input/01-joystick-polling/README.txt @@ -0,0 +1,2 @@ +This example code looks for the current joystick state once per frame, +and draws a visual representation of it. diff --git a/examples/input/01-joystick-polling/joystick-polling.c b/examples/input/01-joystick-polling/joystick-polling.c new file mode 100644 index 0000000000..8f7a3156df --- /dev/null +++ b/examples/input/01-joystick-polling/joystick-polling.c @@ -0,0 +1,193 @@ +/* + * This example code looks for the current joystick state once per frame, + * and draws a visual representation of it. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +/* Joysticks are low-level interfaces: there's something with a bunch of + buttons, axes and hats, in no understood order or position. This is + a flexible interface, but you'll need to build some sort of configuration + UI to let people tell you what button, etc, does what. On top of this + interface, SDL offers the "gamepad" API, which works with lots of devices, + and knows how to map arbitrary buttons and such to look like an + Xbox/PlayStation/etc gamepad. This is easier, and better, for many games, + but isn't necessarily a good fit for complex apps and hardware. A flight + simulator, a realistic racing game, etc, might want this interface instead + of gamepads. */ + +/* SDL can handle multiple joysticks, but for simplicity, this program only + deals with the first stick it sees. */ + +#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ +#include +#include + +/* We will use this renderer to draw into this window every frame. */ +static SDL_Window *window = NULL; +static SDL_Renderer *renderer = NULL; +static SDL_Joystick *joystick = NULL; +static SDL_Color colors[64]; + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + int i; + + SDL_SetAppMetadata("Example Input Joystick Polling", "1.0", "com.example.input-joystick-polling"); + + if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK)) { + SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/input/joystick-polling", 640, 480, 0, &window, &renderer)) { + SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); + return SDL_APP_FAILURE; + } + + for (i = 0; i < SDL_arraysize(colors); i++) { + colors[i].r = SDL_rand(255); + colors[i].g = SDL_rand(255); + colors[i].b = SDL_rand(255); + colors[i].a = 255; + } + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ +SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) +{ + if (event->type == SDL_EVENT_QUIT) { + return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ + } else if (event->type == SDL_EVENT_JOYSTICK_ADDED) { + /* this event is sent for each hotplugged stick, but also each already-connected joystick during SDL_Init(). */ + if (joystick == NULL) { /* we don't have a stick yet and one was added, open it! */ + joystick = SDL_OpenJoystick(event->jdevice.which); + if (!joystick) { + SDL_Log("Failed to open joystick ID %u: %s", (unsigned int) event->jdevice.which, SDL_GetError()); + } + } + } else if (event->type == SDL_EVENT_JOYSTICK_REMOVED) { + if (joystick && (SDL_GetJoystickID(joystick) == event->jdevice.which)) { + SDL_CloseJoystick(joystick); /* our joystick was unplugged. */ + joystick = NULL; + } + } + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once per frame, and is the heart of the program. */ +SDL_AppResult SDL_AppIterate(void *appstate) +{ + int winw = 640, winh = 480; + const char *text = "Plug in a joystick, please."; + float x, y; + int i; + + if (joystick) { /* we have a stick opened? */ + text = SDL_GetJoystickName(joystick); + } + + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); + SDL_RenderClear(renderer); + SDL_GetWindowSize(window, &winw, &winh); + + /* note that you can get input as events, instead of polling, which is + better since it won't miss button presses if the system is lagging, + but often times checking the current state per-frame is good enough, + and maybe better if you'd rather _drop_ inputs due to lag. */ + + if (joystick) { /* we have a stick opened? */ + const float size = 30.0f; + int total; + + /* draw axes as bars going across middle of screen. We don't know if it's an X or Y or whatever axis, so we can't do more than this. */ + total = SDL_GetNumJoystickAxes(joystick); + y = (float) ((winh - (total * size)) / 2); + x = ((float) winw) / 2.0f; + for (i = 0; i < total; i++) { + const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; + const float val = (((float) SDL_GetJoystickAxis(joystick, i)) / 32767.0f); /* make it -1.0f to 1.0f */ + const float dx = x + (val * x); + const SDL_FRect dst = { dx, y, x - SDL_fabsf(dx), size }; + SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); + SDL_RenderFillRect(renderer, &dst); + y += size; + } + + /* draw buttons as blocks across top of window. We only know the button numbers, but not where they are on the device. */ + total = SDL_GetNumJoystickButtons(joystick); + x = (float) ((winw - (total * size)) / 2); + for (i = 0; i < total; i++) { + const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; + const SDL_FRect dst = { x, 0.0f, size, size }; + if (SDL_GetJoystickButton(joystick, i)) { + SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); + } else { + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); + } + SDL_RenderFillRect(renderer, &dst); + SDL_SetRenderDrawColor(renderer, 255, 255, 255, color->a); + SDL_RenderRect(renderer, &dst); /* outline it */ + x += size; + } + + /* draw hats across the bottom of the screen. */ + total = SDL_GetNumJoystickHats(joystick); + x = ((float) ((winw - (total * (size * 2.0f))) / 2.0f)) + (size / 2.0f); + y = ((float) winh) - size; + for (i = 0; i < total; i++) { + const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; + const float thirdsize = size / 3.0f; + const SDL_FRect cross[] = { { x, y + thirdsize, size, thirdsize }, { x + thirdsize, y, thirdsize, size } }; + const Uint8 hat = SDL_GetJoystickHat(joystick, i); + + SDL_SetRenderDrawColor(renderer, 90, 90, 90, 255); + SDL_RenderFillRects(renderer, cross, SDL_arraysize(cross)); + + SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); + + if (hat & SDL_HAT_UP) { + const SDL_FRect dst = { x + thirdsize, y, thirdsize, thirdsize }; + SDL_RenderFillRect(renderer, &dst); + } + + if (hat & SDL_HAT_RIGHT) { + const SDL_FRect dst = { x + (thirdsize * 2), y + thirdsize, thirdsize, thirdsize }; + SDL_RenderFillRect(renderer, &dst); + } + + if (hat & SDL_HAT_DOWN) { + const SDL_FRect dst = { x + thirdsize, y + (thirdsize * 2), thirdsize, thirdsize }; + SDL_RenderFillRect(renderer, &dst); + } + + if (hat & SDL_HAT_LEFT) { + const SDL_FRect dst = { x, y + thirdsize, thirdsize, thirdsize }; + SDL_RenderFillRect(renderer, &dst); + } + + x += size * 2; + } + } + + x = (((float) winw) - (SDL_strlen(text) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f; + y = (((float) winh) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2.0f; + SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); + SDL_RenderDebugText(renderer, x, y, text); + SDL_RenderPresent(renderer); + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate, SDL_AppResult result) +{ + if (joystick) { + SDL_CloseJoystick(joystick); + } + + /* SDL will clean up the window/renderer for us. */ +}