From 9d0b3eded610ccc15f414ecf91fe8b3bfac4801d Mon Sep 17 00:00:00 2001 From: "Ryan C. Gordon" Date: Fri, 20 Sep 2024 22:31:37 -0400 Subject: [PATCH] examples: added renderer/05-rectangles --- examples/CMakeLists.txt | 1 + examples/renderer/05-rectangles/README.txt | 3 + .../05-rectangles/renderer-rectangles.c | 110 ++++++++++++++++++ 3 files changed, 114 insertions(+) create mode 100644 examples/renderer/05-rectangles/README.txt create mode 100644 examples/renderer/05-rectangles/renderer-rectangles.c diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt index fb4db69fa..10ccb05da 100644 --- a/examples/CMakeLists.txt +++ b/examples/CMakeLists.txt @@ -124,6 +124,7 @@ add_sdl_example_executable(renderer-clear SOURCES renderer/01-clear/renderer-cle add_sdl_example_executable(renderer-primitives SOURCES renderer/02-primitives/renderer-primitives.c) add_sdl_example_executable(renderer-lines SOURCES renderer/03-lines/renderer-lines.c) add_sdl_example_executable(renderer-points SOURCES renderer/04-points/renderer-points.c) +add_sdl_example_executable(renderer-rectangles SOURCES renderer/05-rectangles/renderer-rectangles.c) add_sdl_example_executable(audio-simple-playback SOURCES audio/01-simple-playback/simple-playback.c) 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) diff --git a/examples/renderer/05-rectangles/README.txt b/examples/renderer/05-rectangles/README.txt new file mode 100644 index 000000000..26613c706 --- /dev/null +++ b/examples/renderer/05-rectangles/README.txt @@ -0,0 +1,3 @@ +This example creates an SDL window and renderer, and then draws a few +rectangles that change size each frame. + diff --git a/examples/renderer/05-rectangles/renderer-rectangles.c b/examples/renderer/05-rectangles/renderer-rectangles.c new file mode 100644 index 000000000..2fd2ba807 --- /dev/null +++ b/examples/renderer/05-rectangles/renderer-rectangles.c @@ -0,0 +1,110 @@ +/* + * This example creates an SDL window and renderer, and then draws some + * rectangles to it every frame. + * + * This code is public domain. Feel free to use it for any purpose! + */ + +#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; + +#define WINDOW_WIDTH 640 +#define WINDOW_HEIGHT 480 + +/* This function runs once at startup. */ +SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[]) +{ + if (!SDL_Init(SDL_INIT_VIDEO)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't initialize SDL!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + if (!SDL_CreateWindowAndRenderer("examples/renderer/rectangles", WINDOW_WIDTH, WINDOW_HEIGHT, 0, &window, &renderer)) { + SDL_ShowSimpleMessageBox(SDL_MESSAGEBOX_ERROR, "Couldn't create window/renderer!", SDL_GetError(), NULL); + return SDL_APP_FAILURE; + } + + 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. */ + } + 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) +{ + SDL_FRect rects[16]; + const Uint64 now = SDL_GetTicks(); + int i; + + /* we'll have the rectangles grow and shrink over a few seconds. */ + const float direction = ((now % 2000) >= 1000) ? 1.0f : -1.0f; + const float scale = ((float) (((int) (now % 1000)) - 500) / 500.0f) * direction; + + /* as you can see from this, rendering draws over whatever was drawn before it. */ + SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255); /* black, full alpha */ + SDL_RenderClear(renderer); /* start with a blank canvas. */ + + /* Rectangles are comprised of set of X and Y coordinates, plus width and + height. (0, 0) is the top left of the window, and larger numbers go + down and to the right. This isn't how geometry works, but this is + pretty standard in 2D graphics. */ + + /* Let's draw a single rectangle (square, really). */ + rects[0].x = rects[0].y = 100; + rects[0].w = rects[0].h = 100 + (100 * scale); + SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255); /* red, full alpha */ + SDL_RenderRect(renderer, &rects[0]); + + /* Now let's draw several rectangles with one function call. */ + for (i = 0; i < 3; i++) { + const float size = (i+1) * 50.0f; + rects[i].w = rects[i].h = size + (size * scale); + rects[i].x = (WINDOW_WIDTH - rects[i].w) / 2; /* center it. */ + rects[i].y = (WINDOW_HEIGHT - rects[i].h) / 2; /* center it. */ + } + SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255); /* green, full alpha */ + SDL_RenderRects(renderer, rects, 3); /* draw three rectangles at once */ + + /* those were rectangle _outlines_, really. You can also draw _filled_ rectangles! */ + rects[0].x = 400; + rects[0].y = 50; + rects[0].w = 100 + (100 * scale); + rects[0].h = 50 + (50 * scale); + SDL_SetRenderDrawColor(renderer, 0, 0, 255, 255); /* blue, full alpha */ + SDL_RenderFillRect(renderer, &rects[0]); + + /* ...and also fill a bunch of rectangles at once... */ + for (i = 0; i < SDL_arraysize(rects); i++) { + const float w = (float) (WINDOW_WIDTH / SDL_arraysize(rects)); + const float h = i * 8.0f; + rects[i].x = i * w; + rects[i].y = WINDOW_HEIGHT - h; + rects[i].w = w; + rects[i].h = h; + } + SDL_SetRenderDrawColor(renderer, 255, 255, 255, 255); /* white, full alpha */ + SDL_RenderFillRects(renderer, rects, SDL_arraysize(rects)); + + SDL_RenderPresent(renderer); /* put it all on the screen! */ + + return SDL_APP_CONTINUE; /* carry on with the program! */ +} + +/* This function runs once at shutdown. */ +void SDL_AppQuit(void *appstate) +{ + /* SDL will clean up the window/renderer for us. */ +} +