feat: use CMake and SDL3

Based on: https://github.com/Ravbug/sdl3-sample

src/assets/main.cpp

@@ -0,0 +1,195 @@
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <SDL3/SDL_init.h>
+#include <SDL3_ttf/SDL_ttf.h>
+#include <SDL3_mixer/SDL_mixer.h>
+#include <SDL3_image/SDL_image.h>
+#include <cmath>
+#include <string_view>
+#include <filesystem>
+
+constexpr uint32_t windowStartWidth = 400;
+constexpr uint32_t windowStartHeight = 400;
+
+struct AppContext {
+    SDL_Window* window;
+    SDL_Renderer* renderer;
+    SDL_Texture* messageTex, *imageTex;
+    SDL_FRect messageDest;
+    SDL_AudioDeviceID audioDevice;
+    Mix_Music* music;
+    SDL_AppResult app_quit = SDL_APP_CONTINUE;
+};
+
+SDL_AppResult SDL_Fail(){
+    SDL_LogError(SDL_LOG_CATEGORY_CUSTOM, "Error %s", SDL_GetError());
+    return SDL_APP_FAILURE;
+}
+
+SDL_AppResult SDL_AppInit(void** appstate, int argc, char* argv[]) {
+    // init the library, here we make a window so we only need the Video capabilities.
+    if (not SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO)){
+        return SDL_Fail();
+    }
+    
+    // init TTF
+    if (not TTF_Init()) {
+        return SDL_Fail();
+    }
+    
+    // create a window
+   
+    SDL_Window* window = SDL_CreateWindow("SDL Minimal Sample", windowStartWidth, windowStartHeight, SDL_WINDOW_RESIZABLE | SDL_WINDOW_HIGH_PIXEL_DENSITY);
+    if (not window){
+        return SDL_Fail();
+    }
+    
+    // create a renderer
+    SDL_Renderer* renderer = SDL_CreateRenderer(window, NULL);
+    if (not renderer){
+        return SDL_Fail();
+    }
+    
+    // load the font
+#if __ANDROID__
+    std::filesystem::path basePath = "";   // on Android we do not want to use basepath. Instead, assets are available at the root directory.
+#else
+    auto basePathPtr = SDL_GetBasePath();
+     if (not basePathPtr){
+        return SDL_Fail();
+    }
+     const std::filesystem::path basePath = basePathPtr;
+#endif
+
+    const auto fontPath = basePath / "Inter-VariableFont.ttf";
+    TTF_Font* font = TTF_OpenFont(fontPath.string().c_str(), 36);
+    if (not font) {
+        return SDL_Fail();
+    }
+
+    // render the font to a surface
+    const std::string_view text = "Hello SDL!";
+    SDL_Surface* surfaceMessage = TTF_RenderText_Solid(font, text.data(), text.length(), { 255,255,255 });
+
+    // make a texture from the surface
+    SDL_Texture* messageTex = SDL_CreateTextureFromSurface(renderer, surfaceMessage);
+
+    // we no longer need the font or the surface, so we can destroy those now.
+    TTF_CloseFont(font);
+    SDL_DestroySurface(surfaceMessage);
+
+    // load the SVG
+    auto svg_surface = IMG_Load((basePath / "gs_tiger.svg").string().c_str());
+    SDL_Texture* tex = SDL_CreateTextureFromSurface(renderer, svg_surface);
+    SDL_DestroySurface(svg_surface);
+    
+
+    // get the on-screen dimensions of the text. this is necessary for rendering it
+    auto messageTexProps = SDL_GetTextureProperties(messageTex);
+    SDL_FRect text_rect{
+            .x = 0,
+            .y = 0,
+            .w = float(SDL_GetNumberProperty(messageTexProps, SDL_PROP_TEXTURE_WIDTH_NUMBER, 0)),
+            .h = float(SDL_GetNumberProperty(messageTexProps, SDL_PROP_TEXTURE_HEIGHT_NUMBER, 0))
+    };
+
+    // init SDL Mixer
+    auto audioDevice = SDL_OpenAudioDevice(SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK, NULL);
+    if (not audioDevice) {
+        return SDL_Fail();
+    }
+    if (not Mix_OpenAudio(audioDevice, NULL)) {
+        return SDL_Fail();
+    }
+
+    // load the music
+    auto musicPath = basePath / "the_entertainer.ogg";
+    auto music = Mix_LoadMUS(musicPath.string().c_str());
+    if (not music) {
+        return SDL_Fail();
+    }
+
+    // play the music (does not loop)
+    Mix_PlayMusic(music, 0);
+    
+    // print some information about the window
+    SDL_ShowWindow(window);
+    {
+        int width, height, bbwidth, bbheight;
+        SDL_GetWindowSize(window, &width, &height);
+        SDL_GetWindowSizeInPixels(window, &bbwidth, &bbheight);
+        SDL_Log("Window size: %ix%i", width, height);
+        SDL_Log("Backbuffer size: %ix%i", bbwidth, bbheight);
+        if (width != bbwidth){
+            SDL_Log("This is a highdpi environment.");
+        }
+    }
+
+    // set up the application data
+    *appstate = new AppContext{
+       .window = window,
+       .renderer = renderer,
+       .messageTex = messageTex,
+       .imageTex = tex,
+       .messageDest = text_rect,
+       .audioDevice = audioDevice,
+       .music = music,
+    };
+    
+    SDL_SetRenderVSync(renderer, -1);   // enable vysnc
+    
+    SDL_Log("Application started successfully!");
+
+    return SDL_APP_CONTINUE;
+}
+
+SDL_AppResult SDL_AppEvent(void *appstate, SDL_Event* event) {
+    auto* app = (AppContext*)appstate;
+    
+    if (event->type == SDL_EVENT_QUIT) {
+        app->app_quit = SDL_APP_SUCCESS;
+    }
+
+    return SDL_APP_CONTINUE;
+}
+
+SDL_AppResult SDL_AppIterate(void *appstate) {
+    auto* app = (AppContext*)appstate;
+
+    // draw a color
+    auto time = SDL_GetTicks() / 1000.f;
+    auto red = (std::sin(time) + 1) / 2.0 * 255;
+    auto green = (std::sin(time / 2) + 1) / 2.0 * 255;
+    auto blue = (std::sin(time) * 2 + 1) / 2.0 * 255;
+    
+    SDL_SetRenderDrawColor(app->renderer, red, green, blue, SDL_ALPHA_OPAQUE);
+    SDL_RenderClear(app->renderer);
+
+    // Renderer uses the painter's algorithm to make the text appear above the image, we must render the image first.
+    SDL_RenderTexture(app->renderer, app->imageTex, NULL, NULL);
+    SDL_RenderTexture(app->renderer, app->messageTex, NULL, &app->messageDest);
+
+    SDL_RenderPresent(app->renderer);
+
+    return app->app_quit;
+}
+
+void SDL_AppQuit(void* appstate, SDL_AppResult result) {
+    auto* app = (AppContext*)appstate;
+    if (app) {
+        SDL_DestroyRenderer(app->renderer);
+        SDL_DestroyWindow(app->window);
+
+        Mix_FadeOutMusic(1000);  // prevent the music from abruptly ending.
+        Mix_FreeMusic(app->music); // this call blocks until the music has finished fading
+        Mix_CloseAudio();
+        SDL_CloseAudioDevice(app->audioDevice);
+
+        delete app;
+    }
+    TTF_Quit();
+    Mix_Quit();
+
+    SDL_Log("Application quit successfully!");
+    SDL_Quit();
+}