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115 lines
4.3 KiB
C
115 lines
4.3 KiB
C
/*
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* This example creates an SDL window and renderer, and then draws some
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* rotated textures 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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static SDL_Texture *texture = NULL;
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static int texture_width = 0;
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static int texture_height = 0;
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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_Surface *surface = NULL;
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char *png_path = NULL;
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SDL_SetAppMetadata("Example Renderer Rotating Textures", "1.0", "com.example.renderer-rotating-textures");
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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/rotating-textures", 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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/* Textures are pixel data that we upload to the video hardware for fast drawing. Lots of 2D
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engines refer to these as "sprites." We'll do a static texture (upload once, draw many
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times) with data from a bitmap file. */
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/* SDL_Surface is pixel data the CPU can access. SDL_Texture is pixel data the GPU can access.
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Load a .png into a surface, move it to a texture from there. */
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SDL_asprintf(&png_path, "%ssample.png", SDL_GetBasePath()); /* allocate a string of the full file path */
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surface = SDL_LoadPNG(png_path);
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if (!surface) {
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SDL_Log("Couldn't load bitmap: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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SDL_free(png_path); /* done with this, the file is loaded. */
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texture_width = surface->w;
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texture_height = surface->h;
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texture = SDL_CreateTextureFromSurface(renderer, surface);
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if (!texture) {
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SDL_Log("Couldn't create static texture: %s", SDL_GetError());
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return SDL_APP_FAILURE;
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}
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SDL_DestroySurface(surface); /* done with this, the texture has a copy of the pixels now. */
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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_FPoint center;
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SDL_FRect dst_rect;
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const Uint64 now = SDL_GetTicks();
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/* we'll have a texture rotate around over 2 seconds (2000 milliseconds). 360 degrees in a circle! */
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const float rotation = (((float) ((int) (now % 2000))) / 2000.0f) * 360.0f;
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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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/* Center this one, and draw it with some rotation so it spins! */
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dst_rect.x = ((float) (WINDOW_WIDTH - texture_width)) / 2.0f;
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dst_rect.y = ((float) (WINDOW_HEIGHT - texture_height)) / 2.0f;
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dst_rect.w = (float) texture_width;
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dst_rect.h = (float) texture_height;
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/* rotate it around the center of the texture; you can rotate it from a different point, too! */
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center.x = texture_width / 2.0f;
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center.y = texture_height / 2.0f;
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SDL_RenderTextureRotated(renderer, texture, NULL, &dst_rect, rotation, ¢er, SDL_FLIP_NONE);
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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_DestroyTexture(texture);
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/* SDL will clean up the window/renderer for us. */
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}
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