Category Archives: WEBGL

part three..

And to complete the trilogy here another bit of fractal fun (in case your PC is not equipped with a fast enough graphics accelerator you can find a video recording here:


the beauty of numbers..

I just did a little revival of my old WebGL fractal stuff. The two below screens use the latest version of my Commodore C64 emulator to play two fitting music creations by Markus Klein.



vu meters?

Just a little experiment for how to synchronize visualization of additional data streams with the the playback of WebAudio music: The music samples are generated on the fly using a ScriptProcessor emulating some legacy AtariST. In addition to the stereo output the respective ScriptProcessor also generates three streams containing “playback volume” for the AtariST’s internal soundchip voices:


just for fun a more psychedelic WebGL based rendering of the same data (the WebGL here combines an orbit trap fractal with an inverse distortion, and the “music volume” is used to parameterize the rendering):



Fractal Flames

I just completed my latest experiment 🙂 It is a revamped Web version of Orion Sky Lawlor’s “GPU-Accelerated Rendering of Unbounded Nonlinear Iterated Function System Fixed Points” (see here).
For good measure I have added a bit of music interaction 🙂 I suggest you have a look at the live demo here (Chrome recommended). A Youtube recording can be found here.

The music I selected above is by Dexter Britain and licensed under a Creative Commons license. (see

Programming background information:

  • Starting from Dr. Lawlors opengl/C++/Windows program the main step was to get rid of any opengl legacy fixed pipeline rendering and replace it with a programmable pipeline WEBGL equivalent. Then some WEBGL limitations still had to be dealt with, e.g. adding missing WEBGL shader functions, replacement of unsupported for-loops in shaders or unsupported texture modes, etc. Luckily this process proved easier than expected. The resulting WEBGL/JavaScipt program works quite fluidly in Chome (on my GXT460). Firefox’s WEBGL implementation also works for the most part – but it occasionally it crashes for no good reason and it is rather slow in compiling the shaders.
  • Some surprise obstacles came with the attempt to implement the music playback and hook it up WebAudio’s AnalizerNode infrastructure: The first attempt to use some XMLHttpRequest based loading with AudioContext.decodeAudioData() processing proved a total failure, because Firefox’s implementation (versions 31 -33) just fails to decode the (supposedly “invalid”) mp3 data. Also it became obvious that the upfront decoding of the complete mp3 file (in Chrome) adds an unacceptable delay to the music startup. Interestingly playback of the same mp3 file works flawlessly in Chrome as well as in Firefox when using the HTMLAudioElement. So that’s what I am using now. Unfortunately that API is not implemented consistently in the different browsers and particularily the event handling in Firefox leaves a lot to be desired. But even Chrome fails to properly “loop” a song but instead goes into some corrupt state at the end of some (especially longer) songs. Once again browser specific tinkering is called for…
  • The page uses multiple AnaylzerNodes with low-/band- and high-pass filters to detect certain music patterns that are then reflected in the graphics. Unfortunately Firefox again proved a difficult customer: Connecting FilterNodes to the HTMLAudioElement here sporadically leads to corrupted music playback. Also the Firefox FilterNodes produce completely different results than the Chrome ones.

WEBGL and fractals

Did I mention that I love fractals? In fact I do and that’s why I created the below intro:


I am using orbit trap logic that I implemented in a WEBGL fragment shader.   The add-on text scrollers/messages sport an exploding-pixels effect which is done using plain Canvas pixel operations. For good measure I added my WebAudio based SID chiptune playback (see my previous posts).

I guess that next time I’d better leave all the graphics to the GPU .. because my CPU is just getting too old. In case you are using a recent browser and if you have some sort of GPU in your computer, you might try to see the online version by clicking on the above image.


“hello world 3D” version 2..

On my second trip to the world of THREE.js and WEBGL I tried out yet another bunch of “new” things:

  • use of THREE.js EffectComposers and Shaders to create “glow” effects, etc
  • creating lightweight 3D text rendering by rendering a 2D font into a texture and by creating a geometry that then represents each character as two simple textured triangles
  • create THREE.ShaderMaterials (i.e. WEBGL vertex and fragement shaders) to then apply visual effects to the above 3D text (e.g. rolling the characters or exploding the text-page, etc)


Then I came across Felix Woitzel’s fascinating “Travelling Wavefronts” demo and I had to understand how its WEBGL shader logic is done 🙂 After some tinkering I ended up with a slightly cleaned up version of my own with some added visual effect features:


After throwing all of the above together and and adding a bit of WebAudio based SID chiptune playback (see my previous experiment), I ended up with a little Web intro 🙂 Those with a reasonably fast GPU may see it in action here  (due to my old CPU I really like to use as much of the GPU’s power as I can..).


“hello world” 3D with a pinch of concurrency..

By chance I had recently come across a very cool 3D web page and thereby discovered what modern web browsers meanwhile are capable of.

The experiment here is my THREE.js based equivalent of  “hello world” – which I did to just get a first glimps at what it means to do 3D in the browser (the live version is here).
I added a Web Worker based fractal generator to experiment a bit with the benefits of a respective asynchronous approach.

Eventhough they haven’t managed to get the tranparency handling right yet (see here), the guys at THREE.js are certainly doing a great job abstracting from the ugly details of WEBGL wiring! (What they don’t seem to have any clue about is API management and backward compatibility..  e.g. repeatedly inverting the orientation of their 3D coordinate system from one version to the next.. LOL)