[subkamran]

This is awesome but man, reading the canvas portion was a bit distressing. I wonder why they didn't use a game engine to do this? All the work they did has been implemented already in several JS game engines, such as the one I help maintain (it's free and OSS), https://excaliburjs.com. We support all the features they needed including mobile & touch support. They could have also used Phaser (http://phaser.io) too I bet... that has WebGL support for even faster rendering on supported devices.

[madlee]

Hi, I wrote the majority of that part of the project (canvas stuff) & that section of the article – the simple answer is that I have a lot of experience working with the canvas API directly, but little to no experience using any of the popular JS game engines out there (I played around with Phaser years ago, but not very much). I don't think it would've saved me any time to be honest.

[subkamran]

That's totally fair, I get the sentiment. Great job nonetheless!

[Mahn]

...it's not like you have write assembly to get it done, the native canvas API is fairly straightforward. A game engine is a bit of an overkill if all you want to do is place pixels on a canvas.

[subkamran]

But they wanted a lot more than that. Engines like Phaser work hard to take care of browser quirks for things like PointerEvents vs. TouchEvents vs. MouseEvents or supporting mobile devices. Sure, it seems simple at first until you run into those kinds of problems and reinvent the wheel... learning an engine isn't terribly complicated but I understand the sentiment for a one-time project. It just seems like they did so much other planning but didn't want to plan the UI implementation to the same degree?

[emorse]

Like you said, it was a one-time project that wasn't incredibly complex and just needed a one time deployment. And they had UI guys who generally knew what they wanted to and how to do it. I think it would probably have taken them more time to research suitable engines they could rely on than to build the functionality themselves (or use whatever libraries they were already very familiar with.) All engines/libraries end up having quirks that you really only learn through experience.

[nojvek]

Also they were kind of time constrained. WebGL would have been definitely more performant but it has all sorts of hardware issues at times in different devices. I've done plenty of WebGL over the years and seen random GPU crashes where you have to restart the entire machine to unlock your self out.

The canvas trick with typed arrays is brilliant. Using requestAnimationFrame is what any front end dev who knows perf would do. Its like the front end version of cdn with 1 second time out trick.

Also using a layer of library whose code you don't understand in a perf critical application is quite risky. Its better to stick closer to the native browser APIs which you are familiar with. We once had to throw away a library and rewrite code from scratch because their assumptions failed when pushed to the limits. The rewritten code was 100x smaller in size and 10x more performant.

I would have loved to work on something like this but it sucks reddit doesn't have any presence in Seattle.

[brianwawok]

What is the learning curve on a game engine for not game engine developers?

They used tools they knew and knew how to scale. Almost always the tool you know is better than the perfect tool. They know redis and websockets, and they made it work. Beats using some engine know one on staff has ever touched?

[subkamran]

I guess it depends on the engine, or maybe that was a rhetorical question. It doesn't take a month, or even a week, though--maybe to master them but not to learn the API. We've worked hard on our little project to design our engine for non-game developers or veterans, it's only a few lines of code to move a square, or draw an image, for example. But I understand the sentiment, especially for a one-time project.

[emorse]

I don't know, they had several well defined constraints and you don't know what a library is doing under the covers without spending some time with it. A proof of concept engine exploration is different than an app with 100,000 simultaneous users. I wonder how many business days they spent on this thing.