examples: Added input/03-gamepad-polling

examples/CMakeLists.txt

@@ -149,6 +149,7 @@ add_sdl_example_executable(audio-multiple-streams SOURCES audio/04-multiple-stre
 add_sdl_example_executable(audio-planar-data SOURCES audio/05-planar-data/planar-data.c)
 add_sdl_example_executable(input-joystick-polling SOURCES input/01-joystick-polling/joystick-polling.c)
 add_sdl_example_executable(input-joystick-events SOURCES input/02-joystick-events/joystick-events.c)
+add_sdl_example_executable(input-gamepad-polling SOURCES input/03-gamepad-polling/gamepad-polling.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/gamepad_front.bmp)
 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(asyncio-load-bitmaps SOURCES asyncio/01-load-bitmaps/load-bitmaps.c DATAFILES ${CMAKE_CURRENT_SOURCE_DIR}/../test/sample.bmp ${CMAKE_CURRENT_SOURCE_DIR}/../test/gamepad_front.bmp ${CMAKE_CURRENT_SOURCE_DIR}/../test/speaker.bmp ${CMAKE_CURRENT_SOURCE_DIR}/../test/icon2x.bmp)

examples/input/03-gamepad-polling/README.txt

@@ -0,0 +1,3 @@
+This example code looks for the current gamepad state once per frame,
+and draws a visual representation of it. See 01-joystick-polling for the
+equivalent example code for the lower-level joystick API.

examples/input/03-gamepad-polling/gamepad-polling.c

@@ -0,0 +1,221 @@
+/*
+ * This example code looks for the current gamepad state once per frame,
+ * and draws a visual representation of it. See 01-joystick-polling for the
+ * equivalent example code for the lower-level joystick API.
+ *
+ * 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 the joystick interface
+   instead of gamepads. */
+
+/* SDL can handle multiple gamepads, but for simplicity, this program only
+   deals with the first gamepad it sees. */
+
+#define SDL_MAIN_USE_CALLBACKS 1  /* use the callbacks instead of main() */
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+
+/* We will use this renderer to draw into this window every frame. */
+static SDL_Window *window = NULL;
+static SDL_Renderer *renderer = NULL;
+static SDL_Texture *texture = NULL;
+static SDL_Gamepad *gamepad = NULL;
+
+#define WINDOW_WIDTH 640
+#define WINDOW_HEIGHT 480
+
+/* This function runs once at startup. */
+SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
+{
+    char *bmp_path = NULL;
+    SDL_Surface *surface = NULL;
+
+    SDL_SetAppMetadata("Example Input Gamepad Polling", "1.0", "com.example.input-gamepad-polling");
+
+    if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMEPAD)) {
+        SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    if (!SDL_CreateWindowAndRenderer("examples/input/gamepad-polling", WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_RESIZABLE, &window, &renderer)) {
+        SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    if (!SDL_SetRenderLogicalPresentation(renderer, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_LOGICAL_PRESENTATION_STRETCH)) {
+        return SDL_APP_FAILURE;
+    }
+
+    /* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D
+       engines refer to these as "sprites." We'll do a static texture (upload once, draw many
+       times) with data from a bitmap file. */
+
+    /* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access.
+       Load a .bmp into a surface, move it to a texture from there. */
+    SDL_asprintf(&bmp_path, "%sgamepad_front.bmp", SDL_GetBasePath());  /* allocate a string of the full file path */
+    surface = SDL_LoadBMP(bmp_path);
+    if (!surface) {
+        SDL_Log("Couldn't load bitmap: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_free(bmp_path);  /* done with this, the file is loaded. */
+
+    texture = SDL_CreateTextureFromSurface(renderer, surface);
+    if (!texture) {
+        SDL_Log("Couldn't create static texture: %s", SDL_GetError());
+        return SDL_APP_FAILURE;
+    }
+
+    SDL_DestroySurface(surface);  /* done with this, the texture has a copy of the pixels now. */
+
+    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_GAMEPAD_ADDED) {
+        /* this event is sent for each hotplugged gamepad, but also each already-connected gamepad during SDL_Init(). */
+        if (gamepad == NULL) {  /* we don't have a stick yet and one was added, open it! */
+            gamepad = SDL_OpenGamepad(event->gdevice.which);
+            if (!gamepad) {
+                SDL_Log("Failed to open gamepad ID %u: %s", (unsigned int) event->gdevice.which, SDL_GetError());
+            }
+        }
+    } else if (event->type == SDL_EVENT_GAMEPAD_REMOVED) {
+        if (gamepad && (SDL_GetGamepadID(gamepad) == event->gdevice.which)) {
+            SDL_CloseGamepad(gamepad);  /* our controller was unplugged. */
+            gamepad = 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)
+{
+    const char *text = "Plug in a gamepad, please.";
+    static Uint64 leftthumblast = 0xFFFFFFFF;
+    static Uint64 rightthumblast = 0xFFFFFFFF;
+    const Uint64 now = SDL_GetTicks();
+    Sint16 axis_x, axis_y;
+    float x, y;
+    int i;
+
+    if (gamepad) {  /* we have a stick opened? */
+        text = SDL_GetGamepadName(gamepad);
+    }
+
+    SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0xFF, 0xFF);  /* white */
+    SDL_RenderClear(renderer);
+
+    /* 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 (gamepad) {  /* we have a stick opened? */
+        /* where to draw the buttons */
+        const SDL_FRect buttons[] = {
+            { 497, 266, 38,  38 },   /* SDL_GAMEPAD_BUTTON_SOUTH */
+            { 550, 217, 38,  38 },   /* SDL_GAMEPAD_BUTTON_EAST */
+            { 445, 221, 38,  38 },   /* SDL_GAMEPAD_BUTTON_WEST */
+            { 499, 173, 38,  38 },   /* SDL_GAMEPAD_BUTTON_NORTH */
+            { 235, 228, 32,  29 },   /* SDL_GAMEPAD_BUTTON_BACK */
+            { 287, 195, 69,  69 },   /* SDL_GAMEPAD_BUTTON_GUIDE */
+            { 377, 228, 32,  29 },   /* SDL_GAMEPAD_BUTTON_START */
+            { 91,  234, 63,  63 },   /* SDL_GAMEPAD_BUTTON_LEFT_STICK */
+            { 381, 354, 63,  63 },   /* SDL_GAMEPAD_BUTTON_RIGHT_STICK */
+            { 74,  73,  102, 29 },   /* SDL_GAMEPAD_BUTTON_LEFT_SHOULDER */
+            { 468, 73,  102, 29 },   /* SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER */
+            { 207, 316, 32,  32 },   /* SDL_GAMEPAD_BUTTON_DPAD_UP */
+            { 207, 384, 32,  32 },   /* SDL_GAMEPAD_BUTTON_DPAD_DOWN */
+            { 173, 351, 32,  32 },   /* SDL_GAMEPAD_BUTTON_DPAD_LEFT */
+            { 242, 351, 32,  32 },   /* SDL_GAMEPAD_BUTTON_DPAD_RIGHT */
+            { 310, 286, 23,  27 },   /* SDL_GAMEPAD_BUTTON_MISC1 */
+            /* there are other buttons: paddles on the back of the gamepad, touchpads, etc, but this is good enough for now. */
+        };
+
+        SDL_RenderTexture(renderer, texture, NULL, NULL);  /* draw the gamepad picture to the whole window. */
+
+        /* draw green boxes over buttons that are currently pressed. */
+        SDL_SetRenderDrawColor(renderer, 0x00, 0xFF, 0x00, 0xFF);  /* green */
+        for (i = 0; i < SDL_arraysize(buttons); i++) {
+            if (SDL_GetGamepadButton(gamepad, (SDL_GamepadButton) i)) {
+                SDL_RenderFillRect(renderer, &buttons[i]);
+            }
+        }
+
+        SDL_SetRenderDrawColor(renderer, 0xFF, 0xFF, 0x00, 0xFF);  /* yellow */
+
+        /* left thumb axis. */
+        axis_x = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_LEFTX);
+        axis_y = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_LEFTY);
+        if ((SDL_abs(axis_x) > 1000) || (SDL_abs(axis_y) > 1000)) {   /* zero means centered, but it might be a little off zero... */
+            leftthumblast = now;  /* keep drawing, we're still moving. */
+        }
+        if ((now - leftthumblast) < 500) {  /* draw if there was movement in the last half-second. */
+            const SDL_FRect box = { 107 + ((axis_x / 32767.0f) * 30.0f), 252 + ((axis_y / 32767.0f) * 30.0f), 30, 30 };
+            SDL_RenderFillRect(renderer, &box);
+        }
+
+        /* right thumb axis. */
+        axis_x = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_RIGHTX);
+        axis_y = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_RIGHTY);
+        if ((SDL_abs(axis_x) > 1000) || (SDL_abs(axis_y) > 1000)) {   /* zero means centered, but it might be a little off zero... */
+            rightthumblast = now;  /* keep drawing, we're still moving. */
+        }
+        if ((now - rightthumblast) < 500) {  /* draw if there was movement in the last half-second. */
+            const SDL_FRect box = { 397 + ((axis_x / 32767.0f) * 30.0f), 370 + ((axis_y / 32767.0f) * 30.0f), 30, 30 };
+            SDL_RenderFillRect(renderer, &box);
+        }
+
+        /* left trigger. */
+        axis_y = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_LEFT_TRIGGER);
+        if (axis_y > 1000) {   /* zero means unpressed, but it might be a little off zero... */
+            const float height = ((axis_y / 32767.0f) * 65.0f);
+            const SDL_FRect box = { 127, 1 + (65.0f - height), 37, height };
+            SDL_RenderFillRect(renderer, &box);
+        }
+
+        /* right trigger. */
+        axis_y = SDL_GetGamepadAxis(gamepad, SDL_GAMEPAD_AXIS_RIGHT_TRIGGER);
+        if (axis_y > 1000) {   /* zero means unpressed, but it might be a little off zero... */
+            const float height = ((axis_y / 32767.0f) * 65.0f);
+            const SDL_FRect box = { 481, 1 + (65.0f - height), 37, height };
+            SDL_RenderFillRect(renderer, &box);
+        }
+    }
+
+    x = (((float) WINDOW_WIDTH) - (SDL_strlen(text) * SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE)) / 2.0f;
+    if (gamepad) {
+        y = (float) (WINDOW_HEIGHT - (SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE + 2));
+    } else {
+        y = (((float) WINDOW_HEIGHT) - SDL_DEBUG_TEXT_FONT_CHARACTER_SIZE) / 2.0f;
+    }
+    SDL_SetRenderDrawColor(renderer, 0x00, 0x00, 0xFF, 0xFF);  /* blue */
+    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)
+{
+    SDL_DestroyTexture(texture);
+    SDL_CloseGamepad(gamepad);
+    /* SDL will clean up the window/renderer for us. */
+}