Rewrote AudioDriverJavaScript to support multiple processor nodes.
The old (and deprecated) ScriptProcessorNode when threads are not
available, and the new AudioWorklet API when threads are enabled.
The new implementation uses two ring buffers and a shared state to
communicated with the AudioWorklet thread.
The audio.worklet.js JavaScript file is always added to the export
template, but only really used (and downloaded) in the thread build.
The API is implemented in javascript, and generates C functions that can
be called from godot.
This allows much cleaner code replacing all `EM_ASM` calls in our C++
code with plain C function calls.
This also gets rid of few hacks and comes with few optimizations (e.g.
custom cursor shapes should be much faster now).
The size of the audio buffer was incorrectly doubled when creating the
script processor.
latencyHint is expressed in seconds, not milliseconds.
Additionally, on some browsers it actually affect the performance and
stability of the audio driver.
For this reason it has been completely disabled (interactive) and a not
has been left for future reference.
This should be made available in emscripten in a decent way.
Possibly after unmount, to free the database lock and allow performing
operations on it from javascript after the Emscripten Runtime has
exited.
This should fix some of the audio stuttering issues when the HTML5
export is compiled with threads support.
The API should be ported to AudioWorklet to (hopefully) be perfect.
That though, cannot be backported to 3.2 due to extra restriction of
AudioWorklet (which only runs in SecureContext, and needs a polyfill for
Safari).
The engine now expects to emscripten FS to be setup and sync-ed before
main is called. This is exposed via `Module["initFS"]` which also allows
to setup multiple persistence paths (internal use only for now).
Additionally, FS syncing is done **once** for every loop if at least one
file in a persistent path was open for writing and closed, and if the FS
is not syncing already.
This should potentially fix issues reported by users where "autosave"
would not work on the web (never calling `syncfs` because of too many
writes).
Marcel Admiraal
Aaron Franke
Fabio Alessandrelli