Allows to set up application initialization parameters, including some WebGL context creation parameters.
"compressed assets" - makes the app load a compressed scene in .xz format instead of a regular .gltf file (see Asset compression for more info);
"default fullscreen button" - enables the default fullscreen button located in the top right corner;
"transparent background" - makes the background transparent so that the underlying parts of a web page become visible through the WebGL canvas;
"enable screenshots" - makes it possible to properly capture screenshots from the WebGL canvas (sets the preserveDrawingBuffer property of the WebGL context to true);
"fade annotations" - makes annotations fade when they are blocked by scene objects.
Removes the default preloader and exposes event callbacks to allow for handling preloader progress events.
In the following example, a custom preloader is represented with a container HTML element (e.g., a <div>) with the id "preloader". Inside it, there is another element with the id "loading progress" (e.g., a <span>), in which % of loading is printed using the persentage puzzle. In addition to that, the width of the third element (e.g., a <div>) is dynamically changed to graphically represent the loading progress.
