keii.dev
Simple Directmedia Layer
1/*
2 * This example code creates an SDL window and renderer, and then clears the
3 * window to a different color every frame, so you'll effectively get a window
4 * that's smoothly fading between colors.
5 *
6 * This code is public domain. Feel free to use it for any purpose!
7 */
8
9#define SDL_MAIN_USE_CALLBACKS 1 /* use the callbacks instead of main() */
10#include <SDL3/SDL.h>
11#include <SDL3/SDL_main.h>
12
13/* We will use this renderer to draw into this window every frame. */
14static SDL_Window *window = NULL;
15static SDL_Renderer *renderer = NULL;
16
17/* This function runs once at startup. */
18SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
19{
20 SDL_SetAppMetadata("Example Renderer Clear", "1.0", "com.example.renderer-clear");
21
22 if (!SDL_Init(SDL_INIT_VIDEO)) {
23 SDL_Log("Couldn't initialize SDL: %s", SDL_GetError());
24 return SDL_APP_FAILURE;
25 }
26
27 if (!SDL_CreateWindowAndRenderer("examples/renderer/clear", 640, 480, 0, &window, &renderer)) {
28 SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
29 return SDL_APP_FAILURE;
30 }
31
32 return SDL_APP_CONTINUE; /* carry on with the program! */
33}
34
35/* This function runs when a new event (mouse input, keypresses, etc) occurs. */
36SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event *event)
37{
38 if (event->type == SDL_EVENT_QUIT) {
39 return SDL_APP_SUCCESS; /* end the program, reporting success to the OS. */
40 }
41 return SDL_APP_CONTINUE; /* carry on with the program! */
42}
43
44/* This function runs once per frame, and is the heart of the program. */
45SDL_AppResult SDL_AppIterate(void *appstate)
46{
47 const double now = ((double)SDL_GetTicks()) / 1000.0; /* convert from milliseconds to seconds. */
48 /* choose the color for the frame we will draw. The sine wave trick makes it fade between colors smoothly. */
49 const float red = (float) (0.5 + 0.5 * SDL_sin(now));
50 const float green = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 2 / 3));
51 const float blue = (float) (0.5 + 0.5 * SDL_sin(now + SDL_PI_D * 4 / 3));
52 SDL_SetRenderDrawColorFloat(renderer, red, green, blue, SDL_ALPHA_OPAQUE_FLOAT); /* new color, full alpha. */
53
54 /* clear the window to the draw color. */
55 SDL_RenderClear(renderer);
56
57 /* put the newly-cleared rendering on the screen. */
58 SDL_RenderPresent(renderer);
59
60 return SDL_APP_CONTINUE; /* carry on with the program! */
61}
62
63/* This function runs once at shutdown. */
64void SDL_AppQuit(void *appstate, SDL_AppResult result)
65{
66 /* SDL will clean up the window/renderer for us. */
67}
68