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69 lines
2.5 KiB
C
69 lines
2.5 KiB
C
/*
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* This example code creates an SDL window and renderer, and then clears the
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* window to a different color every frame, so you'll effectively get a window
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* that's smoothly fading between colors.
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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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/* 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 Clear", "1.0", "com.example.renderer-clear");
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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/clear", 640, 480, 0, &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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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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const double now = ((double)SDL_GetTicks()) / 1000.0; /* convert from milliseconds to seconds. */
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/* choose the color for the frame we will draw. The sine wave trick makes it fade between colors smoothly. */
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const float red = (float) (0.5 + 0.5 * SDL_sin(now));
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const float green = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 2 / 3));
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const float blue = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 4 / 3));
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SDL_SetRenderDrawColorFloat(renderer, red, green, blue, SDL_ALPHA_OPAQUE_FLOAT); /* new color, full alpha. */
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/* clear the window to the draw color. */
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SDL_RenderClear(renderer);
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/* put the newly-cleared rendering on the screen. */
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SDL_RenderPresent(renderer);
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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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