build.sh

#!/bin/sh

set -ex

# A few steps are necessary to get this build working which makes it slightly
# nonstandard compared to most other builds.
#
# * First, the Rust standard library needs to be recompiled with atomics
#   enabled. to do that we use Cargo's unstable `-Zbuild-std` feature.
#
# * Next we need to compile everything with the `atomics` and `bulk-memory`
#   features enabled, ensuring that LLVM will generate atomic instructions,
#   shared memory, passive segments, etc.
#
# * Finally, `-Zbuild-std` is still in development, and one of its downsides
#   right now is rust-lang/wg-cargo-std-aware#47 where using `rust-lld` doesn't
#   work by default, which the wasm target uses. To work around that we find it
#   and put it in PATH

RUSTFLAGS='-C target-feature=+atomics,+bulk-memory' \
  cargo build -v --target wasm32-unknown-unknown -Z build-std=std,panic_abort \
  --features "wasm,gl"

# Note the usage of `--no-modules` here which is used to create an output which
# is usable from Web Workers. We notably can't use `--target bundler` since
# Webpack doesn't have support for atomics yet.
wasm-bindgen target/wasm32-unknown-unknown/debug/pong_wasm.wasm \
  --out-dir pkg --no-modules

# worker.js crashes because it does not have `AudioContext` / `webkitAudioContext` in scope.
# This prevents it from crashing.
audio_context_workaround="const lAudioContext = (typeof AudioContext !== 'undefined' ? AudioContext : typeof webkitAudioContext !== 'undefined' ? webkitAudioContext : null)"

sed -i "s/const lAudioContext.\+\$/${audio_context_workaround}/" 'pkg/pong_wasm.js'