I am the creator of Photopea. It is not fully open-source. What do you mean by running a webapp from a command line? I never heard of it (I also don't use a command line).
There's a recent issue [1] in the wasm-bindgen repo that explains this, but essentially:
- In this demo the WebGLRenderingContext was created on the Rust side (technically by calling a light JS shim), but it could've just as well have been passed in from JS.
- This means that JS could very easily have had access to the WebGLRenderingContext.
- This means that we cannot guarantee that it is immutable. Who is to say that there isn't a line of JS `gl.mutated! = true;` that we don't know about? We have no guarantees that whoever instantiated this WebAssembly module isn't doing something funky.
- So we treat most DOM / JS APIs as if they have interior mutability, so more or less you can think of them as `RefCell`'s [2]
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As an aside. When you work with WebGL you're just making calls to the GPU and your state on the GPU gets mutated. The object just controls state (WebGlRenderingContext) does not get mutated (aside from maybe a couple things that I'm forgetting..?).
As in.. `gl.viewport` doesn't actually mutate `gl`. But again.. just a small aside!
In general the idea here is that we can't guarantee that there is only one mutable reference so there is no point in calling these things `&mut`, even for things that really do mutate.
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So yup! Interior mutability without runtime checks for many of the APIs is "the right way" in today's idiomatic Rust + WASM + DOM access since you can't guarantee that there isn't foul play going on from whoever instantiated the module.
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Does this cause issues? It hasn't (noticeably) for me yet but I'm only a couple months into using `web_sys` so I haven't worked with every single DOM API.. so grain of salt!
Totally agree that there's room to look more water-y (depending on your application's needs).
One thing that can be done is playing around with the numbers / uniforms in the fragment shader to change the look. For many use cases you can get pretty far with that without actually changing the implementation in this demo.
If a more physically based level of realism is needed (like the water ripples on click in the demo that you linked) you can use techniques like height simulation based on a wave equation [1].
You'll of course need to balance realism with realtime feasibility - but often times getting a much better look comes down to tweaking some numbers until things look good!
Miiiiinor point/caveat here but jotting it down just for others that might be less familiar!
Today WebGL is commonly referred to as a JS API because pretty much every WebGL app is written using JS.
But, even though that MDN link quite literally says "JavaScript API", it turns out that WebGL is entirely specified in WebIDL and isn't coupled to JS.
Because of this, `wasm-bindgen` [1] is able to auto-generate all of the WebGL bindings [2] that I used for this demo.
Today `wasm-bindgen` automatically generates some JS shims because that's the only way to call the WebGL APIs at this time, but once anyref and host bindings land you'll be able to interface with the WebGL APIs directly without going through JS.
`wasm-bindgen` already plans to just replace those JS shims with direct host bindings.
But yup - totally agree with your points here - just sharing this minor detail that will be more relevant in the future!
Yup! I'm actually working on a project that needs to use WebGL but can't use JS bindings for a quirky reason. So I'm actually super glad you posted this — it's a great resource. Thank you!
- I see that I poorly communicated this in the title, but I was actually shooting less for "Rust/WASM makes this better!!" and more for "Hey, this is possible with pretty much just Rust/WASM!" I ended up hand writing about 10 lines of JS [1] in total
- More minor point - WebGL commands don't need to be called via JS [2] after anyref and host bindings land, and I think that it's important for people to know that it's possible to do things on the web without JS (whether that's a good idea is very situational)!
So yeah apologies if the title could be a bit better - but the main goal was to share with others that it's possible to build 3d experiences on the web with Rust today!
And - just to not come off wrong here - I'm not saying whether this is right or wrong and when to go this route. I am just interested in demonstrating how to do it :)
But all in all you're right - all of this same experience could totally be built with only JS if someone so desired!
Right now it you call into JS to interact with the DOM but when the host bindings proposal sees fruit it’ll replace the JS shims with direct DOM manipulation!
It isn’t clear how they will allow safe access to the DOM without GC. Maybe they’ll take an approach like Microsoft did with UWP and use reference counting?
Would be interesting if it would be possible to take the Rust approach and guarantee at parse/compilation time that the DOM interactions are safe without runtime overhead. Probably a terrible idea for mobile devices though...
Yew is awesome and just knowing that something like that was possible inspired Percy. I also looked at Yew's `html!` macro when figuring out how Percy's could / should work.
One difference is that Yew is powered by stdweb and Percy is powered by wasm-bindgen.
I'm personally SUPER bullish on wasm-bindgen because it's been designed from day 1 to be able to take advantage of the host bindings proposal when it materializes.
Host bindings tl;dr is that instead of needing to go through JS to interact with browser APIs you can interact with them directly.
Another difference is that to my knowledge Yew doesn't support server side rendering ( which was why I couldn't use it even though I wanted to :( ).
Without having used Yew I don't want to comment any further than those high level differences.
I can say that a big focus of Percy is to be a grab bag of modules / tooling for frontend Rust web apps with a major focus of you being able to swap out the parts that you think are bad for other peoples' better implementations. That dream isn't realized yet.. but I think that Rust's generics / traits could make this feel very clean!
>One difference is that Yew is powered by stdweb and Percy is powered by wasm-bindgen.
>I'm personally SUPER bullish on wasm-bindgen because it's been designed from day 1 to be able to take advantage of the host bindings proposal when it materializes.
I find it funny that you mentioned that. I actually was trying out wasm-bindget/yew recently and ended up using yew because of the wasm-bindgen limitations (mostly related to using anything with generics in the type signature).
The experience will probably improve on the future, but right now yew's actor model seems like a much simpler way to encapsulate rust libraries.
1. Pulls in your application crate
2. Initializes your app (more or less sets initial state
3. Renders your app's virtual DOM into an HTML string
4. Serves the HTML to the client, along with the initial state serialized into JSON in a script tag (using serde-json)
5.Also serves the WASM script and the JS that initializes the WASM
So that's your server crate. Then your client crate also pulls in your same application crate and you compile it to WebAssembly and that's what runs browser side.
Feel free to let me know if any of that was poorly explained!
This is good enough for an example, but for a "real" web server, you wouldn't do this; you'd use a framework that handles a lot of this kind of thing for you. I think this code was adapted from the final chapter of the Rust book, which is mostly about learning how to write a simple thing than being production-ready.
If you don't need server side rendering you can have one Rust file but you also need a JS file to initialize the WebAssembly module. So just one file isn't reasonably possible.
For a server side rendered app you need to have a cargo workspace with 3 crates (they can be in the same repo so not a huge deal).
One crate is a `cdylib` that you compile to WebAssembly to serve your app to the client. This is a light wrapper around your actual application.
One crate is your actual application.
And one crate is your server, which is also a light wrapper around your actual application.
what i want to see is to have all logic to be centered around features, and have a framework compile the server side and client server out of one logical piece of code, if that even makes sense.
a bit like in the old days of php when you'd have the serverside code and html rendered in their, but this time nearly everything is running on the client unless the client can't be trusted.
you could have some kind of ring system, where something can never run on the client right up to always run on client, but all in one file.
ASP.NET does this, you use its components and it generates client side javascript. In a more functional way, there's another language that does this caled Opa! http://opalang.org/
I can't quite tell - but it seems like you have to hit their servers in order to run this from the command line and the code isn't fully open source?
Regardless - thanks a lot for sharing!