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https://github.com/sogaiu/jaylib-wasm-demo
Demo of using jaylib in a web browser
https://github.com/sogaiu/jaylib-wasm-demo
janet raylib wasm
Last synced: about 2 months ago
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Demo of using jaylib in a web browser
- Host: GitHub
- URL: https://github.com/sogaiu/jaylib-wasm-demo
- Owner: sogaiu
- Created: 2022-02-06T06:44:07.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2024-01-18T11:59:55.000Z (8 months ago)
- Last Synced: 2024-04-27T16:32:32.513Z (5 months ago)
- Topics: janet, raylib, wasm
- Language: Janet
- Homepage:
- Size: 1.21 MB
- Stars: 19
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# jaylib-wasm-demo
A demo of using [jaylib](https://github.com/janet-lang/jaylib) in a web browser
## Overview
The current approach is to build a small program that embeds [janet](https://janet-lang.org) and is linked to [Raylib](https://www.raylib.com/). The program loads and executes an example game written in Janet that uses Raylib via jaylib.
The program is made executable in a web browser by being compiled by [Emscripten](https://emscripten.org/).
The goal of this demo is to produce appropriate `.wasm`, `.js`, `.html`, and related files and then to test their functionality via a web browser. Before compilation via Emscripten can take place, some pieces need to be prepared:
* `main.c` - the aforementioned small program
* `janet.c` + support files - for embedding janet
* `libraylib.a` - "HTML5-ready" Raylib static library
* `game.janet` - a small game written in Janet / jaylib
## Prerequisites
* Emscripten 3.1.3 (other versions might work)
* Usual build tools (e.g. to get Emscripten working on Windows Python is needed)
* Janet
## Steps
* Ensure repository has been cloned recursively:
```
git clone --recursive https://github.com/sogaiu/jaylib-wasm-demo
```
* For *nixen, with emsdk under `~/src/emsdk`:
```
source ~/src/emsdk/emsdk_env.sh
janet build-unix.janet
```
* For Windows, with emsdk in a sibling directory of this repository (likely need to do via a Native Tools Command Prompt):
```
..\emsdk\emsdk_env.bat
janet build-windows.janet
```
* Start a web server to serve the built files:
For a machine with python3, that might be:
```
python3 -m http.server --directory public
```
* Try out the results:
Visit http://localhost:8000 and click on `main.html`
## Notes
The "game loop" currently relies on invoking a modified version of
`janet_pcall` named `janet_pcall_keep_env` to invoke Janet code.
`janet_pcall` resets passed fibers (or creates completely new ones)
which implies that dynamic variables are not preserved between
invocations because dynamic variables are associated with specific
fibers. If `janet_pcall_keep_env` is passed a non-NULL fiber, the
associated environment (and hence dynamic variables) are reused.
An alternative is to use `janet_continue`, which allows one to pass a
fiber which doesn't get reset. Since the same fiber can be reused
without resetting, dynamic variables can be preserved between
invocations. However, Emscripten then produces somewhat broken code [1]
unless `ASYNCIFY` is specified when compiling (this was discovered via
a DevTools console message). Using `ASYNCIFY` does yield running
code, but the resulting code is likely slower due to added
instrumentation. Additionally, at present, audio hasn't been made to
work for the `janet_continue` + `ASYNCIFY` combination (at least in
this demo)...
In summary, current advice is:
* if audio is desired, either use `janet_pcall` and don't use dynamic
variables, or use `janet_pcall_keep_env`.
* if audio is unneeded, one can use `janet_continue` instead.
[1] Currently, it's not clear why `ASYNCIFY` is necessary. bakpakin's
`webrepl.c` for janet-lang.org's web REPL also uses
`janet_continue` but `ASYNCIFY` does not appear to be needed
there. One difference that might be relevant is that the demo
would be triggering `janet_continue` via
`emscripten_set_main_loop`, while `webrepl.c`'s `janet_continue`
is user-triggered.
## Issues
* On Windows if `janet build-windows.janet` fails in the final
compilation step, it may be worth trying [this
workaround](https://github.com/emscripten-core/emscripten/issues/10551#issuecomment-608566377).
## Thanks
* bakpakin
* MikeBeller
* pyrmont
* raysan5
* saikyun
* yumaikas
* ZakharValaha