Atlas - joystick-polling.c
Home / ext / SDL / examples / input / 01-joystick-polling Lines: 1 | Size: 8031 bytes [Download] [Show on GitHub] [Search similar files] [Raw] [Raw (proxy)][FILE BEGIN]1/* 2 * This example code looks for the current joystick state once per frame, 3 * and draws a visual representation of it. 4 * 5 * This code is public domain. Feel free to use it for any purpose! 6 */ 7 8/* Joysticks are low-level interfaces: there's something with a bunch of 9 buttons, axes and hats, in no understood order or position. This is 10 a flexible interface, but you'll need to build some sort of configuration 11 UI to let people tell you what button, etc, does what. On top of this 12 interface, SDL offers the "gamepad" API, which works with lots of devices, 13 and knows how to map arbitrary buttons and such to look like an 14 Xbox/PlayStation/etc gamepad. This is easier, and better, for many games, 15 but isn't necessarily a good fit for complex apps and hardware. A flight 16 simulator, a realistic racing game, etc, might want the joystick interface 17 instead of gamepads. */ 18 19/* SDL can handle multiple joysticks, but for simplicity, this program only 20 deals with the first stick it sees. */ 21 22#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */ 23#include <SDL3/SDL.h> 24#include <SDL3/SDL_main.h> 25 26/* We will use this renderer to draw into this window every frame. */ 27static SDL_Window *window = NULL; 28static SDL_Renderer *renderer = NULL; 29static SDL_Joystick *joystick = NULL; 30static SDL_Color colors[64]; 31 32/* This function runs once at startup. */ 33SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) 34{ 35 int i; 36 37 SDL_SetAppMetadata("Example Input Joystick Polling", "1.0", "com.example.input-joystick-polling"); 38 39 if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_JOYSTICK)) { 40 SDL_Log("Couldn't initialize SDL: %s", SDL_GetError()); 41 return SDL_APP_FAILURE; 42 } 43 44 if (!SDL_CreateWindowAndRenderer("examples/input/joystick-polling", 640, 480, SDL_WINDOW_RESIZABLE, &window, &renderer)) { 45 SDL_Log("Couldn't create window/renderer: %s", SDL_GetError()); 46 return SDL_APP_FAILURE; 47 } 48 49 for (i = 0; i < SDL_arraysize(colors); i++) { 50 colors[i].r = SDL_rand(255); 51 colors[i].g = SDL_rand(255); 52 colors[i].b = SDL_rand(255); 53 colors[i].a = 255; 54 } 55 56 return SDL_APP_CONTINUE; /* carry on with the program! */ 57} 58 59/* This function runs when a new event (mouse input, keypresses, etc) occurs. */ 60SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event) 61{ 62 if (event->type == SDL_EVENT_QUIT) { 63 return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */ 64 } else if (event->type == SDL_EVENT_JOYSTICK_ADDED) { 65 /* this event is sent for each hotplugged stick, but also each already-connected joystick during SDL_Init(). */ 66 if (joystick == NULL) { /* we don't have a stick yet and one was added, open it! */ 67 joystick = SDL_OpenJoystick(event->jdevice.which); 68 if (!joystick) { 69 SDL_Log("Failed to open joystick ID %u: %s", (unsigned int) event->jdevice.which, SDL_GetError()); 70 } 71 } 72 } else if (event->type == SDL_EVENT_JOYSTICK_REMOVED) { 73 if (joystick && (SDL_GetJoystickID(joystick) == event->jdevice.which)) { 74 SDL_CloseJoystick(joystick); /* our joystick was unplugged. */ 75 joystick = NULL; 76 } 77 } 78 return SDL_APP_CONTINUE; /* carry on with the program! */ 79} 80 81/* This function runs once per frame, and is the heart of the program. */ 82SDL_AppResult SDL_AppIterate(void *appstate) 83{ 84 int winw = 640, winh = 480; 85 const char *text = "Plug in a joystick, please."; 86 float x, y; 87 int i; 88 89 if (joystick) { /* we have a stick opened? */ 90 text = SDL_GetJoystickName(joystick); 91 } 92 93 SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); 94 SDL_RenderClear(renderer); 95 SDL_GetWindowSize(window, &winw, &winh); 96 97 /* note that you can get input as events, instead of polling, which is 98 better since it won't miss button presses if the system is lagging, 99 but often times checking the current state per-frame is good enough, 100 and maybe better if you'd rather _drop_ inputs due to lag. */ 101 102 if (joystick) { /* we have a stick opened? */ 103 const float size = 30.0f; 104 int total; 105 106 /* 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. */ 107 total = SDL_GetNumJoystickAxes(joystick); 108 y = (winh - (total * size)) / 2; 109 x = ((float) winw) / 2.0f; 110 for (i = 0; i < total; i++) { 111 const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; 112 const float val = (((float) SDL_GetJoystickAxis(joystick, i)) / 32767.0f); /* make it -1.0f to 1.0f */ 113 const float dx = x + (val * x); 114 const SDL_FRect dst = { dx, y, x - SDL_fabsf(dx), size }; 115 SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); 116 SDL_RenderFillRect(renderer, &dst); 117 y += size; 118 } 119 120 /* draw buttons as blocks across top of window. We only know the button numbers, but not where they are on the device. */ 121 total = SDL_GetNumJoystickButtons(joystick); 122 x = (winw - (total * size)) / 2; 123 for (i = 0; i < total; i++) { 124 const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; 125 const SDL_FRect dst = { x, 0.0f, size, size }; 126 if (SDL_GetJoystickButton(joystick, i)) { 127 SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); 128 } else { 129 SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); 130 } 131 SDL_RenderFillRect(renderer, &dst); 132 SDL_SetRenderDrawColor(renderer, 255, 255, 255, color->a); 133 SDL_RenderRect(renderer, &dst); /* outline it */ 134 x += size; 135 } 136 137 /* draw hats across the bottom of the screen. */ 138 total = SDL_GetNumJoystickHats(joystick); 139 x = ((winw - (total * (size * 2.0f))) / 2.0f) + (size / 2.0f); 140 y = ((float) winh) - size; 141 for (i = 0; i < total; i++) { 142 const SDL_Color *color = &colors[i % SDL_arraysize(colors)]; 143 const float thirdsize = size / 3.0f; 144 const SDL_FRect cross[] = { { x, y + thirdsize, size, thirdsize }, { x + thirdsize, y, thirdsize, size } }; 145 const Uint8 hat = SDL_GetJoystickHat(joystick, i); 146 147 SDL_SetRenderDrawColor(renderer, 90, 90, 90, 255); 148 SDL_RenderFillRects(renderer, cross, SDL_arraysize(cross)); 149 150 SDL_SetRenderDrawColor(renderer, color->r, color->g, color->b, color->a); 151 152 if (hat & SDL_HAT_UP) { 153 const SDL_FRect dst = { x + thirdsize, y, thirdsize, thirdsize }; 154 SDL_RenderFillRect(renderer, &dst); 155 } 156 157 if (hat & SDL_HAT_RIGHT) { 158 const SDL_FRect dst = { x + (thirdsize * 2), y + thirdsize, thirdsize, thirdsize }; 159 SDL_RenderFillRect(renderer, &dst); 160 } 161 162 if (hat & SDL_HAT_DOWN) { 163 const SDL_FRect dst = { x + thirdsize, y + (thirdsize * 2), thirdsize, thirdsize }; 164 SDL_RenderFillRect(renderer, &dst); 165 } 166 167 if (hat & SDL_HAT_LEFT) { 168 const SDL_FRect dst = { x, y + thirdsize, thirdsize, thirdsize }; 169 SDL_RenderFillRect(renderer, &dst); 170 } 171 172 x += size * 2; 173 } 174 } 175 176 x = (((float) winw) - (SDL_strlen(text) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f; 177 y = (((float) winh) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2.0f; 178 SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); 179 SDL_RenderDebugText(renderer, x, y, text); 180 SDL_RenderPresent(renderer); 181 182 return SDL_APP_CONTINUE; /* carry on with the program! */ 183} 184 185/* This function runs once at shutdown. */ 186void SDL_AppQuit(void *appstate, SDL_AppResult result) 187{ 188 if (joystick) { 189 SDL_CloseJoystick(joystick); 190 } 191 192 /* SDL will clean up the window/renderer for us. */ 193} 194[FILE END](C) 2025 0x4248 (C) 2025 4248 Media and 4248 Systems, All part of 0x4248 See LICENCE files for more information. 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