Month: November 2020

Categories
graphics shaders

WebGL for noobs: The Shadey Student

In the last post, I wrote about getting wowed by WebGL fragment shader hacks. They are simultaneously fascinating and baffling, how can something seeming so simple give rise to such magic?

… an uninformed public tends to confuse scholarship with magicianry…

Foundation and Empire – Isaac Asimov (1952)

It seems then that I am the uninformed public. Again.

Over the years I’ve come to realise that trying to explain something to others is the way to really understand something. It’s an approach that has been broadly given the name: ‘The Feynman Technique’. Which is to say, I think, it’s something Feynman did in his teachings at CalTech. Rather than a bite sized self-help method developed by him to sell stocking filler books. But all props to the Feynman legend, the system works and so I’m going to aim to gain understanding by trying to explain what’s going on under the hood here on this blog. Note that I’m not a mathematician and so there are probably better explanations of how some of this works than mine, most likely what you need, if you want the good stuff is here.

Armed with all the heavy-hitting celebrity ‘thinking’ quotes that I need to motivate, me I’ve set out on this endeavour. The first step of which is creating tools for the job. Whilst shadertoy.com is the bomb and my inspiration, there are two reasons I’ve decided not to use it for this:

  1. I would need to publish my shaders on shadertoy.com in order to embed them here. What I intend to do in explaining is a little too trivial for what I think shadertoy.com should be used for;
  2. Shadertoy.com seems a bit slow, probably because it’s really popular! Better that I don’t add to that burden (although three page views a week isn’t going to hurt them!) but also better to have control over the content. IMHO.

Therefore I’ve created a little WebGL Javascript embedding tool. Based upon Mozilla’s great WebGL tutorials and inspired by shadertoy.com. It’s stripped down to simplify what needs to be done but the shaders I create with it should be compatible with shadertoy.com when, and if, I do want to publish something.

Finally the last part of the stack is having a graphing tool that I can use to embed custom plots into these pages to explain the functions that are used in the shaders – because this is where the magic is. For that I’m using Python 3.8 with Matplotlib. It’s not the prettiest but it’s definitely more than good enough.

Let the fun begin.

Categories
article graphics shaders

New Toys

I have been interested in computer graphics for a long time but never really interested enough to make some positive steps toward it. Like a lot of people, I have tried to get a basic app working in OpenGL or DirectX but never really got very far. It was all a bit intimidating.

However things have changed. These days, on DirectX, there are a load of fantastic tutorials on the internet, as well as seriously helpful libraries. If you’re interested in getting some physics working there’s a few good books and often the content is backed up with source code. For WebGL (which is a flavour of OpenGL) there’s great tutorials to help, and really cool insights into how it works.

There’s quite a lot to take in before you can really grok what the graphics pipeline does, whatever API flavour you chose. It was whilst trying to figure out how shaders work that I stumbled across some stunning examples of what is possible. What I didn’t realise, at first, is that the examples I was looking at are simply fragment shaders.

If you don’t know how 3D graphics works you might say ‘so what?’. But let’s just say it’s not the easy route to getting 3D computer graphics done – not to me anyway. The mathematics involved looks in a lot of ways harder, but the programming looks way easier. Programming this way is mostly declarative, there’s no bonkers API and there are far fewer loops because the magic is in the power of the GPU and the shader loop.

My only problem is that shadertoy.com doesn’t quite work how I want it to. For one thing it keeps timing out (guess they need more funds, so I added some through Patreon), but that aside I wanted a bit more control over the shader and how it can be embedded. Partially for this blog but also to learn a bit more WebGL.

That happened two weeks ago. I’ve been messing around trying to get something working for this site and making some embeddable shaders that I can embed directly here. I think I’m almost there …