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114 lines
4.4 KiB
C
114 lines
4.4 KiB
C
/*
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* This example creates an SDL window and renderer, and then draws some
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* rectangles to it every frame.
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*
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* This code is public domain. Feel free to use it for any purpose!
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*/
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#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */
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#include <SDL3/SDL.h>
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#include <SDL3/SDL_main.h>
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/* We will use this renderer to draw into this window every frame. */
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static SDL_Window *window = NULL;
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static SDL_Renderer *renderer = NULL;
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#define WINDOW_WIDTH 640
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#define WINDOW_HEIGHT 480
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/* This function runs once at startup. */
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SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
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{
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SDL_SetAppMetadata("Example Renderer Rectangles", "1.0", "com.example.renderer-rectangles");
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if (!SDL_Init(SDL_INIT_VIDEO)) {
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SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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if (!SDL_CreateWindowAndRenderer("examples/renderer/rectangles", WINDOW_WIDTH, WINDOW_HEIGHT, SDL_WINDOW_RESIZABLE, &window, &renderer)) {
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SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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SDL_SetRenderLogicalPresentation(renderer, WINDOW_WIDTH, WINDOW_HEIGHT, SDL_LOGICAL_PRESENTATION_LETTERBOX);
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs when a new event (mouse input, keypresses, etc) occurs. */
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SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
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{
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if (event->type == SDL_EVENT_QUIT) {
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return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */
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}
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs once per frame, and is the heart of the program. */
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SDL_AppResult SDL_AppIterate(void *appstate)
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{
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SDL_FRect rects[16];
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const Uint64 now = SDL_GetTicks();
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int i;
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/* we'll have the rectangles grow and shrink over a few seconds. */
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const float direction = ((now % 2000) >= 1000) ? 1.0f : -1.0f;
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const float scale = ((float) (((int) (now % 1000)) - 500) / 500.0f) * direction;
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/* as you can see from this, rendering draws over whatever was drawn before it. */
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SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE); /* black, full alpha */
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SDL_RenderClear(renderer); /* start with a blank canvas. */
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/* Rectangles are comprised of set of X and Y coordinates, plus width and
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height. (0, 0) is the top left of the window, and larger numbers go
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down and to the right. This isn't how geometry works, but this is
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pretty standard in 2D graphics. */
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/* Let's draw a single rectangle (square, really). */
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rects[0].x = rects[0].y = 100;
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rects[0].w = rects[0].h = 100 + (100 * scale);
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SDL_SetRenderDrawColor(renderer, 255, 0, 0, SDL_ALPHA_OPAQUE); /* red, full alpha */
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SDL_RenderRect(renderer, &rects[0]);
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/* Now let's draw several rectangles with one function call. */
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for (i = 0; i < 3; i++) {
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const float size = (i+1) * 50.0f;
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rects[i].w = rects[i].h = size + (size * scale);
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rects[i].x = (WINDOW_WIDTH - rects[i].w) / 2; /* center it. */
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rects[i].y = (WINDOW_HEIGHT - rects[i].h) / 2; /* center it. */
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}
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SDL_SetRenderDrawColor(renderer, 0, 255, 0, SDL_ALPHA_OPAQUE); /* green, full alpha */
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SDL_RenderRects(renderer, rects, 3); /* draw three rectangles at once */
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/* those were rectangle _outlines_, really. You can also draw _filled_ rectangles! */
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rects[0].x = 400;
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rects[0].y = 50;
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rects[0].w = 100 + (100 * scale);
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rects[0].h = 50 + (50 * scale);
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SDL_SetRenderDrawColor(renderer, 0, 0, 255, SDL_ALPHA_OPAQUE); /* blue, full alpha */
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SDL_RenderFillRect(renderer, &rects[0]);
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/* ...and also fill a bunch of rectangles at once... */
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for (i = 0; i < SDL_arraysize(rects); i++) {
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const float w = (float) (WINDOW_WIDTH / SDL_arraysize(rects));
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const float h = i * 8.0f;
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rects[i].x = i * w;
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rects[i].y = WINDOW_HEIGHT - h;
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rects[i].w = w;
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rects[i].h = h;
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}
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SDL_SetRenderDrawColor(renderer, 255, 255, 255, SDL_ALPHA_OPAQUE); /* white, full alpha */
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SDL_RenderFillRects(renderer, rects, SDL_arraysize(rects));
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SDL_RenderPresent(renderer); /* put it all on the screen! */
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return SDL_APP_CONTINUE; /* carry on with the program! */
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}
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/* This function runs once at shutdown. */
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void SDL_AppQuit(void *appstate, SDL_AppResult result)
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{
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/* SDL will clean up the window/renderer for us. */
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}
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