PHphoboslab·Aug 4, 2024
The original JavaScript engine “Impact” from 2010 is at the end of its life; the C rewrite “high_impact” is new and will (potentially) be around for as long as we have C compilers and some graphics API.
The JavaScript engine had a lot of workarounds for things that are not necessary anymore and some things that just don't work that well with modern browsers. From the top of my head:
- nearest neighbor scaling for pixel graphics wasn't possible, so images are scaled at load time pixel by pixel[1]. Resizing the canvas after the initial load wasn't possible with this. Reading pixels from an image was a total shit show too, when Apple decided to internally double the Canvas2D resolution for their “retina” devices, yet still reporting the un-doubled resolution[2].
- vendor prefixes EVERYWHERE. Remember those? Fun times. Impact had it's own mec
Read the rest
hanism to automatically resolve the canonical name[3]
- JS had no classes, so classes are implemented using some trickery[4]
- JS had no modules, so modules are implemented using some trickery[5]
- WebAudio wasn't a thing, so Impact used <Audio> which was never meant for low latency playback or multiple channels[6] and generally was extremely buggy[7]. WebAudio was supported in later Impact versions, but it's hacked in there. WebAudioContext unlocking however is not implemented correctly, because back then most browsers didn't need unlocking and there was no "official" mechanism for it (the canonical way now is ctx.resume() in a click handler). Also, browser vendors couldn't get their shit together so Impact needed to handle loading sounds in different formats. Oh wait, Apple _still_ does not fully support Vorbis or Opus 14 years later.
- WebGL wasn't a thing, so Impact used the Canvas2d API for rendering, which is _still_ magnitudes slower than WebGL.
- Touch input wasn't standardized and mobile support in general was an afterthought.
- I made some (in hindsight) weird choices like extending Number, Array and Object. Fun fact: Function.bind or Array.indexOf wasn't supported by all browsers, so Impact has polyfills for these.
- Weltmeister (the editor) is a big piece of spaghetti, because I didn't know what I was doing.
Of course all of these shortcomings are fixable. I actually have the source for “Impact2” doing all that with a completely new editor and bells and whistles. It was very close to release but I just couldn't push it over the finish line. I felt bad about this for a long time. I guess high_impact is my attempt for redemption :]
[1] https://github.com/phoboslab/Impact/blob/master/lib/impact/i...
[2] https://phoboslab.org/log/2012/09/drawing-pixels-is-hard
[3] https://github.com/phoboslab/Impact/blob/master/lib/impact/i...
[4] https://github.com/phoboslab/Impact/blob/master/lib/impact/i...
[5] https://github.com/phoboslab/Impact/blob/master/lib/impact/i...
[6] https://phoboslab.org/log/2011/03/multiple-channels-for-html...
[7] https://phoboslab.org/log/2011/03/the-state-of-html5-audio