Basic webasm build

[patrickelectric]

It gets starting but there is a bunch of stuff to do yet. I'm opening this as a draft to see if someone continue this work, maybe myself in the future.

[davidbuzz]

I did a wasm sitl branch a while back just to see if I could.... I just commented out stuff that didnt work, or hacked stuff. https://github.com/davidbuzz/ardupilot/tree/buzz-wasm-testing

key gotchas:

• build summary didnt work
• sitl needed to not exit on startup when tcp/udp failed
• used the "emsdk" tool
  • had to empty SHLIB_MARKER and STLIB_MARKER as '-Wl,-Bdynamic' and '-Wl,-Bstatic' are not supported by emscrypten/clang
  • had to disable scripting
  • had to force add -pthread to the linker flags

used this: https://github.com/emscripten-core/emsdk.git ./emsdk install latest ./emsdk activate latest export CC=emcc export CXX=em++ export EMCC_DEBUG=1

[davidbuzz]

extension project that could make this really valuable would be to enable "networking in browser" with a Tailscale wasm client, like is done here: https://github.com/leaningtech/webvm .. they have a "enable browser networking" functionality that can connect to TailScale server/s over websockets, ie does not require any ongoing server-side proxy. Tailscale has a free plan. you could connect a GCS that is elsewhere ( eg in another tab, on another puter) to the sitl-in-browser or other stuff.

[patrickelectric]

My original idea was to integrate a full 3D environment, GCS and SITL (this PR) in the browser for simulation and decreasing the gap between ArduPilot and new developers.

[davidbuzz]

My original idea was to integrate a full 3D environment, GCS and SITL (this PR) in the browser for simulation and decreasing the gap between ArduPilot and new developers.

...yup, that use-case, where all your other backend is on the same "box" wouldnt require tailscale, but would require a backend-server that supports websockets, and adding explicit websockets support to sitl as a compile-time alternative to raw TCP