Added shadow, working on UI adapting

src/main.cpp

@@ -259,7 +259,7 @@ int main(int argc, char *argv[]) {
         }*/
         const Uint32 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN | SDL_WINDOW_FULLSCREEN_DESKTOP;
 #else
-        const Uint32 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN;
+        const Uint32 windowFlags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN | SDL_WINDOW_ALLOW_HIGHDPI;
 #endif
 
         ZL::Environment::window = SDL_CreateWindow(
@@ -272,6 +272,16 @@ int main(int argc, char *argv[]) {
         SDL_GLContext ctx = SDL_GL_CreateContext(ZL::Environment::window);
         SDL_GL_MakeCurrent(ZL::Environment::window, ctx);
 
+        // On HiDPI displays the drawable (physical) size is larger than the
+        // logical window size. Use the drawable size so the GL framebuffer
+        // covers every physical pixel and the image stays sharp.
+        {
+            int drawW, drawH;
+            SDL_GL_GetDrawableSize(ZL::Environment::window, &drawW, &drawH);
+            ZL::Environment::width  = drawW;
+            ZL::Environment::height = drawH;
+        }
+
         game.setup();
 
         while (!game.shouldExit()) {