+ extern SDL_Window *sdlwindow;
+ SDL_GL_SwapWindow(sdlwindow);
+
+ // try to limit this to 60fps, even if vsync fails.
+ Uint32 now;
+ static Uint32 frameticks = 0;
+ const Uint32 endticks = (frameticks + 16);
+ while ((now = SDL_GetTicks()) < endticks) { /* spin. */ }
+ frameticks = now;