no image





my bookmarks

no image
no image
no image


I was in the web.Mon Jul 09, 2007
This is spam. Please Move Along.Thu May 24, 2007
The First YearWed Jan 17, 2007
In a Rush.Wed Nov 08, 2006
kernel-panicTue Oct 17, 2006
Two days left ...Tue Jul 11, 2006
holly days!Wed May 10, 2006
The summer is coming!!!Tue Apr 25, 2006
omg!Fri Apr 07, 2006
Dreaming of LightThu Mar 30, 2006
Spheres againMon Mar 27, 2006
1337 @n|) n3\/\/ |)3516nFri Mar 10, 2006
RaythrowersFri Mar 03, 2006
der Rosenmontag kommt!Sun Feb 26, 2006
phresnel.org++Fri Feb 24, 2006
Patchdays!Wed Feb 22, 2006
A happy Valentinesday you all!!Tue Feb 14, 2006
Hallo und herzlich willkommen!!Fri Feb 10, 2006
A wonderful evening I wish!!Mon Feb 06, 2006
Good morning everyone!!Thu Feb 02, 2006
Hey there, it′s 0112am and I′m kinda tired....Wed Feb 01, 2006

I was in the web.Mon Jul 09, 2007

The last weeks I've crawled the web, I've read tons of stuff, not all related to programming, but some sites in that respect are real gems. I will quick-post some of my favorites of my journey (I'll probably miss some, but will edit this entry later then):

some very usefull reference cards, e.g. for vi, TeX, linux, PHP, C and more (meh, the c++ refcard is an MFC one) www.digilife.be/quickreferences/indexe.html and this one: jamesie.de/index.html
not really new to me, but highly recommendable: The official fsf-site (==free software foundation) www.fsf.org | Richard Stallmans website (founder of the fsf, contains very intereseting reads)
interesting GNU sites: www.gnu.org | free books | GNU fun
introductions to 4k-programming and linux-assembly (if you are familiar with intel-style assembler(that is (probably), if you come from windoze-assembly)). 4k: in4k.untergrund.net | http://keyj.s2000.ws/?p=29
linux-asm: asm.sourceforge.net
hinted to by Thierry Berger-Perrin (see ompf): What are floating point numbers? How does the algebra behind it look like? Guard Digits? Rounding? Division by Zero? IEEE? etc., for beginners and experts. "What Every Computer Scientist Should Know About Floating-Point Arithmetic"
the jargon file. read it, and learn about the true meaning of hacking and its history. www.catb.org/jargon/ | directory | The Story of Mel (a real programmer who codes on steel, like real men do) | Master Foo enlightens the Script-Kiddie

This is spam. Please Move Along.Thu May 24, 2007

Just written a little story about me for the people who wonder who I am or what I am doing.


My name is Sebastian Mach (the 1983 a.d. edition), by some known under the pseudonym 'greenhybrid', hence the URL of this site phresnel.org, or simply 'seb'.

I'm interested in tons of stuff, but rarely find the time to explore it all. The biggest interest in charge of all others is definitely programming, or simply 'coding', which is a slang-word for some people (but not for me and most of the others who know me). To make the circle sharper, my main interest within the discipline of coding is graphics-programming, especially Ray Tracing. For those who don't know what that actually means, simply speaking: I am not someone working with the graphics software, I am someone who develops it. (okay, okay, I've never done anything very user-friendly, but technically that example fits into the concept).

Well, now follows a short summary about what I have done the last years in my favorite discipline:

  • 1999-2004: the time of not being connected to the world through some cables

    • the dark age, I don't remember exactly (from 1999-2000?).

      What I remember is that I came in touch with an old and crappy and totally virused 286/32MHz, as far as I remember, with DOS and Q-Basic, which was the only running 'program', so I began 'it' (what a lucky pure accident).
      Armed with what is called Q-Basic, a friend and me had brutal and disturbing "coding-battles", first experiences with variables (later we even became aware of the fact that a variable's name can be made up of more than just one letter, yay!), goto's, if's and so on...
      A pity he then gave it up for some reason, while I was getting more and more knowledge about things like arrays and file-i/o (actually, I knew file-i/o at first and used that to temporarily save and load dozens of data-packs, again and again for each frame. Not kidding, I just did not know about something like 'arrays'). And all my sprites then were hard-/handcoded couples of pixels (their positions saved/loaded in an file each frame, for sure), wheee!
      ...phew, lemme get some air and a cig-pause (yeah, I know, bad habit, and sorry for my bad writing style at this point, really rushing through it due to time constraints)...
    • 2000-2001 (? not exact date).

      From time to time the voices came: C, C, C, ... C!. A lucky accident then wanted me to grab a game-programming-starter-box (with the evil MSVC6 inside, plus Marc Saltzman's book "Game Design", and some other stuff), so I finally got a C/C++-compile and dev-environment (which I used for years then, nothing wrong with Redomd at that time, syserrors(C) were simply "normal").
      So I actually learned "true programming", without gotos and pasta. It all looked so cryptic and cipherish...but I was hard enough to withstand my antiknowledge. A lot of delphi'ish programming: Add Button, double click it, write source, don't understand what is going on...Slowly I got into it, became aware of typedefs, structures, classes, and hey: pointers! The latter one is maybe one of the largest hurdles for every newbie-coder. But once you got it, it is no problem to use things like "int foo( int **x ) { free(*x); *x = 0; }".
    • approx. 2001-2003 (low entropy time)

      I've done mostly Direct X/Graphics coding. I actually started with OpenGL, but no internet and low documentation in the MSDN doc (while I had a DirectX 6,1 SDK with proper documention in the above mentioned starter-kit) made me skip it.
      I called this section low-entropy time because w/out an internet connection and double-w/out money (for buying books) gaining knowledge is really a mess.
      Here and there a scratchy project like a very small ray-tracer or a never ended bomberman clone in 3d, called xploderz, with some funny elements (hide/bomb/run, a bit of MetalGearSolid). Actually I have also tried to understand the A*-algorithm, but with just a poor article in a pc-magazine it was impossible to me.
      (quick note to me: expand this section a bit, lookup old backups to achieve this)
  • 2004: break! or: The time of not coding because of the Wehrpflicht

    In short: The Bundeswehr called, I became a proud member of the Bundesmarine, i.e. a "Signalbetriebsgast". That means I knew the morse alphabet, I could morse (morsing is not just the standard alphabet, but also a lot of "special signs" for things like "End of Conversation" and so), I knew the whole international flag-alphabet (and a lot of signals), and I was able to do some "Sprechfunk" (I guess it's radiotelephony in english).

    After the so called "Grundausbildung" in Bremerhaven at the Marine-Operations-Schule (the first three months, were you learn the basics all soldiers have to know [run, hide, shoot, duck and cover and more] plus the specifics of your "job" there) I went to Hamburg, where the frigate F212 "Karlsruhe" waited for me in the dockyard "Blohm+Voss" (actually the same dockyard where the "Bismarck" in WWII was built, and I saw exactly it's dock plus a small part of it's plating).

    Three months or so later, me with two golden stripes on my shoulders (meaning "Obergefreiter" [Lance Corporal or Private 1st Class, in english, I think]), we then leaved Hamburg to get to Wilhemshaven, the "main base" for the german frigates. A nice town at the Jadebusen, not far from the north sea.

    I don't get into more detail now, you would be bored (or I would be hung ;)), but one thing that brandmarked itself into my synapsery was the approx 12 (ideal case), but up to 16 (the general case, Deutsche Bahn, you might have heard of it;) ) hours of train time in total, per weekend...

    After those 9 faboulous months I will never forget I had a lot of free time, and I played "GTA-San Andreas" in the late 2004.

  • 2005-today: the time of enlightenment, finally having an internet connection, yay!

    In the soon 2005 I had to acclimate myself to coding again. And I wrote the root-engine, a never ended story, but the ladscape part of it was really good! But to save time here, just be aware that it has it's own blog here.

    The biggest thing that happened 2005 was Julia! I let this stand alone at this point. Awesome.

    Finally having an internet connection in late 2005/soon 2006, I surfed the web and found some amazing stuff about Ray Tracing, so, at first just for fun, I wrote a small ray-tracer again: glass, glass++, gladius and now xitrace (all with their own respecticve diary here) should tell the rest of my story so far. Plus a bit of Fractals, L-Systems and Compiler writing. What they call internet is amazing, since it caused my most creative year ever, and is going on to give me knowlede. But enough of that now, all my work since January 2006 is on this site!

    If you really reached this point in the story (or just have read a small part of it): Thank you for reading!

some more short infos about me (grabbed from my deviantart-page)

  • Current Age: 23
  • Current Job: Applications Developer
  • Current Residence: NRW, Germany
  • Favourite movie: gladiator, saw, cube, full metal jacket, saving private ryan, black hawk down, bands of brothers
  • Favourite band or musician: system of a down, rammstein, slipknot, korn, aphex twin, ochre, felix laband, autechre, and more...
  • Favourite genre of music: rock and idm, I also like irish folklore (remember Gangs of NY, huh? ... how cool)
  • Operating System: Debian GNU/Linux
  • MP3 player of choice: Amarok
  • Shell of choice: bash
  • Favourite game: all time favorite: Civilization III, Shogun/Medieval/Rome: Total War
  • Favourite cartoon character: Homer S. from Springfield, somewhere in the US
  • Tools of the Trade: Anjuta, SciTE, gcc 4.1, bison/flex, my fingers, Kaffee, Neurons

The First YearWed Jan 17, 2007

A Year of Onlineness

"Hallo zusammen und willkommen!". Those were the first words on this very homepage. It was Saturday, January 14, 2006 (there was no english version from startup, but more on that later)

Thank you all for sharing your precious time here, thanks for your interest, for everything. Special thanks go out to my beloved Julia, for giving me the time to code, and, especially, for her interest in my work, I love you!

Now follows a short summary of my programming work of every month, including some screenies, I hope you also enjoy that.

January: Startup, or Hallo zusammen und willkommen!

Startup. I finally have a little homepage again. At that time, the whole page was written in pure html. The design was hardcoded. And I had not much time to program.

Nothing special going around regarding my graphics-coding except for the root-engine.

February: Internationalization, or Hey there, it′s 0112am and I′m kinda tired....

Startup of the english version. Duly for Feb 01. And dude, I was abs(tired), bet.

Furthermore, I was tired of all the html-hardcoding. So, not much coding again except for the php-migration of my homepage.

March: A new passion, or want a glass of liguid and sour sauce?

Ray Tracing? ... Yes! The beginning of my efforts on Ray Tracing. That was the start of a new passion. I posted some images on devmaster.net and the guys there were talking in some cryptographic jargon about "acceleration structures", "MRays per seconds" and I dunno what else. I felt like a beginner. So I wanted to show them that I am not (for sure I actually was one regarding Ray Tracing) ;)

I've never read that much papers and never learned so much in general like in the year 2006. Ray Tracing, or the "glass" ray tracer, was the initializing big bang for that. And tbp (ompf.org), who "offended" me (just kidding dude) in my glass-post on devmaster was not innocent for my incidental ambitions.

April: Accelerated Ray Tracing, or The key is kd

Awesome: Ray Tracing with a few thousand polygons. Builduing a kd-tree was damn hard for me at that time, and it was damn hard to get a clue about the traversal mechanism Wald mentioned (Actually I was using my very own traversal algorithm); but it was a big motivation that the image at the right (below) took only 4.5 seconds with three colored lights and about 20k triangles.

But for some reason, it does not look trés realistique...

May: Global Illumination, or at least a glimpse on

Knew not much, instead done much. I did some particle-tracing and traced some images with about 10000 samples per pixel. If I had read Kayija's paper first....

On the other hand, my particle-tracing helped me a lot to understand the basic physics of lighting, even if I only traced primary bounces.

I also gave a try on finishing xploderz. I have to say, the code was kinda pasta. At first it looked good. It was fun to reactivate an older project and to add some neat features.

June: Photon Mapping, or memory, a lot of memory

After reading Jensens paper on Photon Mapping I had to implement them to get some caustics. I was struggling with global illumination over and over. I did direct lighting via Monte Carlo, and indirect lighting fully by Photons... I should have known better. But failing here means succeeding in the future, I think. At least the images did not look too bad.

Afterwards, it was lycium who told me he doesn't "like photons [...] because of the smeary look". I skipped further work on that topic and started a pure path tracer later...

I found some guys who started the scripting of some levels for xploderz. We also had a little forum with some active discussions. It looked really promising. But it's the time, the time is rare. Too rare.

Nevertheless, Thanks deja_vu, LJ_1102 and jph for your level-designs and Hanatarou and Broesel for your awesome tunes!

to be continued...

So far, thanks for reading and excuse me for my bad style of writing, I really rushed through it. The latter six months will be summarized in some days, see you later o/

In a Rush.Wed Nov 08, 2006

Hey there and welcome!

It's a pity that you don't get any academical degree by just reading a bunch of so called "white-papers". I am reading a lot of them (yet not enough to get an "et al"-postfix in my name) at the moment about Perlin-Noise, Hyper-Textures, Lighting-Models, Procedural City-, Street- and Building-Generation etc...More than I can ever implement (probably).

So I have to handle the interesting things one by one. My implementation curriculum of the last weeks:

  • performant SAH-Kd-Tree
  • MLRTA (not yet perfect)
  • Perlin Noise landscapes with ray marching, later with ray tracing
  • L-Systems (just got the basics in a 1 1/2 hour coding session and rendered a little Sierpinski Gasket using it)
  • other not so relevant things
My plan for the next weeks:
  • Advanced L-Systems (it's a simple but (I mean it) mighty system, like Perlin Noise) for ...
    • ... plant generation
    • ... city (yes, city) generation
  • Further optimization of the Perlin Landscape (don't even try to global illuminate the terrain at the moment)
  • other not so relevant things

Lot to do, lot to learn. See you!

At last, I want to thank you, Julia, for the best year in my life, nothing better ever happened to me, I love you!

kernel-panicTue Oct 17, 2006

Welcome folks!

sorry, been no updates for a while here: kernel-panic, holiday-trip with my sweetheart, etc...

question: What does it mean when the linux operating system does not boot up, saying "kernel-panic"?
answer (just two words): Hardware. Problems.
consequences: Failed memory reads/writes, or, to say it cleary, an unmountable harddisk-partition (namely "/home"), meaning my works of the last weeks are NULL.

I decided to write a new ray tracer from scratch, a performance-oriented one, not object-oriented (its not 8k-democode, the design is still object-oriented).

As you may have considered, the design of the page changed from infernal flipcode darkness to a lighter, modern one. How do you like it? Feel free to give feedback via the contact form.

Now have a good time exploring this page, see you later!

Two days left ...Tue Jul 11, 2006

... and this site will have six months on his back. A lot of things happened since January 14, and because of that there will be a little surprise.

What are you doing these days?

The updates don't lie, I am totally bound by raytracing. I have not thought Raytracing is such a great and scientific thing when I have seriously begun with it.
From the simple ray-/sphere-intersection, reflections, refractions and soft-shadows up to monte-carlo-raytracing in his full grace appearing as path-tracing, photon-mapping, caustics, global illumination and infinitely more of those nice things.

What happened to xploderz?

Click here for information: xploderz-diary. It's not dead, the opposite is the case. My target is the best graphics in a bomberman-clone.

Other activities?

Yes. I have cleaned up the german wikipedia-article about path-tracing: it's here. Several things have not been correct. The discussion can be found here.
Furthermore I am working on a secret project on rayracing, only three persons are inaugurated: My angel, another person and me. It's about making raytracing available for a wider spectrum of (german-speaking, but shhhht!) people

Greetings ...

... go to everyone who knows me, especially to:
Michael, Thomas, Anica + Florian, Sabrina + Thomas, Dominica + Thomas, André + Freundin and very especially my dear Angel, ich liebe dich!

holly days!Wed May 10, 2006
Hey there!
I'm on holiday until sunday, so don't expect any update before 0 ante meridiem the monday! EMail-traffic will be reduced til then, bye!
Ich bin bis Sonntag im Urlaub, bitte erwartet keine Updates bis 0 ante meridiem kommenden Montag, EMail-Verkehr findet dann eingeschränkt statt! Ciao!

The summer is coming!!!Tue Apr 25, 2006
Hello there! Yeah, today the sun is shining, swimming under the heaven is not far away, the Birds are singing, the nature is wearing green again!

Anyway, I keep up working and not putting my legs on the table ( okay, maybe I am putting my legs on the table, but I am working :D )

I have rewritten the complete raytracer. That was a pretty good idea, I am on the best way to realtime-raytracing
I have posted a new forum: http://forum.phresnel.org. There the dev- and tec-talk is, you also find some must-read-material.
I am working on an own guestbook-implementation, the current one is buggy on some browsers....

Everything good for you, go out enjoying the sun before the universe dies the energy-death ( and thus it will be! )

omg!Fri Apr 07, 2006
O my god!
There was a exploit-hole on this page for remote-inclusions. I have kicked it! ...that was dangerous... safety > fun, so it's got to be!
There are new images, this time in 1024x768, rendered with my glass-raytracer. Have a look a them, I think they are nice!
New functions: For those who are not using a mail-client like thunderbird there is a new and comfortable way to contact me, just click 'contact' in the menu!

Greeting go out to Nope, Micha, Dominika+Kmobz, Sabrina+Tukatz, Anica+Flow and, for sure, Julia, my angel, I love you!

Update: Gratulations! You are the 2000th Visitor!! So, phresnel.org celebrates a little jubilary today!

Dreaming of LightThu Mar 30, 2006
Hello everybody and welcome!!
The last days I have dev'ed my raytracer glass. I've build in spheres, reflections and now refractions. Convex-bodies made of planes are ready but I haven't made pics of it yet. You can see that effect when laying a piece of plane-glass on a text...try it out

Nope I have not forgot you: Everything good for you and Happy Birthday!!!

Spheres againMon Mar 27, 2006
There have been no "welcomes" the last weeks, but maybe you recognized I haven't been sleeping in bed . But as first: WELCOME FOLKS! Okay, for you there is not much new stuff, but I worked on the site (in background, some new cool administration functions) and I dev'ed the glass of liquid and sour sauce a bit. The spheres are back, and performance is good until now.
You'll get some new updates on the glass-topic the next days!

1337 @n|) n3\/\/ |)3516nFri Mar 10, 2006
I wish you to have had a nice week (argghh) and say welcome!
Like you can see the layout has changed again. At the top you can see some images from the far-content. You can select the language at the top, the domains www.greenhybrid.de | de.phresnel.org | en.phresnel.org work correctly again, you can see the five newest content in the startupscreen incl. the category of the content whichyou can click on directly and (getting some air.......) you can watch the whole site in leetspeak, a tribute to the eighties (very pervers if you have never seen 1337) and I began to code my raytracer, but see the Glass-Log

I wish you to have a nice weekend and greetings go out to Flow and Anica, Kmobz and Dominika, Nope, Tukatz and Sabrina and Michael, especially, my Julia, I love you!!!

P.S.: The title means "Leet and new Design"
and!!! A happy birthday to you flow, let tonite be honestly!

RaythrowersFri Mar 03, 2006
Hello there!
Karneval is over and doesn′t come back the next time.
There haven′t been new contents the last weeks because of two reasons:
-1: PHP-Update of the whole page and self-educating exactly this (PHP is the reason why I am updating the page from within the school-lesson right now ;) )
-2: Karneval

What I am planning to do is a quality-raytracer; but it will be performance-coded from the beginning on because I maybe make a realtime-raytracer of it.
I have to quit now, greetings go out to all outa there and especially to my angel and my darling, Julia, tips glass, it′ our day!!

der Rosenmontag kommt!Sun Feb 26, 2006
So, tomorrow it comes, the Rosenmontag! I hope you came here and enjoyed some rheinischen Karneval.

I have posted two new old flipcode-iotd′s. One of them is officially posted by Thomas Terkatz, but inofficially them have been made by me, sorry Thomas!
Greetings go out to Thomas Kriegers, Thomas Terkatz and Sabrina, Michael (sorry, this time I don not forget you!), Thomas Knops and Dominika, Florian and Annica and especially to you, my darling, my angel, my Julia, our love is huge, we will have a lot of great, wonderfull years!!!

phresnel.org++Fri Feb 24, 2006
Hi there! The patchdays are nearly over and some changes have been made on the layout:
1) The colors are no more candy, the flower-factor has been screwed down
2) I banned the topframe to increase the line of sight in the content-pages
3) There is finally a directory in the content-pages.
I am planning to code a filtering-function in the content-pages, so you can watch only the five newest content for example, or the newest contents in general, independent of the category.
It is friday and there is a party today. It is a bit sadly, too, because a friend′s grandma′s way has gone to the end. It is serious, so I talk in our mother tongue:

Mein herzliches Beileid an dieser Stelle fuer alle Verwandten, Freunde und Bekannten, und speziell dir. Du weisst wer gemeint ist.

Patchdays!Wed Feb 22, 2006
Maybe you recognized I officially have not updated the page the last days ;) But the heaviest changes have been made. You are not watching _intro.en.html / _intro.de.html here anymore but a databased PHP-form
Like I said once before PHP is really cool. In the next time there will be more updates again. By the way, I am planning to dev a new style and a style-select-rollout.

So, tomorrow it is Altweiber and on the weekend the party goes on the Niederrhein, so please do not worry when I am not updating again. Maybe some of you come here and be part of the celebrations!?
Keep clean, we see us!

A happy Valentinesday you all!!Tue Feb 14, 2006
Today a month ago this site went online with 1307 visitors until now. I wanna thank you all for this!!

My gamedev status is unchanged, but I can say PHP is somewhat cool, if you're dev'ing websites try it out! It's good for you ;)

Okay, now it's 0am, meaning the valentines day's over, but I can say, it was fantastic. My beloved Julia, maybe you're reading this: Thank you for the great time, the box, the heart, the book, for your love!!!

Hallo und herzlich willkommen!!Fri Feb 10, 2006
This week I have not worked on my engine :(, this status will be kept some more days :((. The reason is that I learned a bit PHP and to use that I needed a server with support for exactly this. That means there will be a real imageviewer instead of just href-ing to the images, there will be statistics and more.

On February 7 I had a little record: 214 visitors in 24 hours, that makes me a bit proud ;) and motivates me to keep on! A big THANK YOU for this, you know who you are!!

Greetings go out to Flow and Annica, Tukatz and Sabrina, Nope, Kmobz and his new darling, Chad Walker, Mr. Heyer (I dont know if he has ever seen my homepage;)), Antonio, Dominik, Ilona, Dieter, Astrid, the whole IT54 and all I forgot this time. And, of course: Julia, my angel, my darling, I love you!!!

A wonderful evening I wish!!Mon Feb 06, 2006
The last days I did some hackcoding on my engine. There are some new Images in the root-log. Nothing crushing, but I build in a small surprise for the developers.

From today on www.greenhybrid.de has two new addresses:


Using www.phresnel.org you can click on your prefererd language.
New, too: the e-mail-tdl changed from .de to .net: root@phresnel.org

Greetings, until the next update!!!

Good morning everyone!!Thu Feb 02, 2006
I upped new material in the root-log. What some fogging and skyboxing can result in....
Greetings go out to the schaag-community and ...
a big, big Thank You my angel for simply everything for what has been, what is and what will be. I love you!!!

Hey there, it′s 0112am and I′m kinda tired....Wed Feb 01, 2006
I′m proud to present you the english version of this homepage.
Everyone is welcome to leave some comments in the guestbook, fell free to edit!!! Just to get this introduction complete you′ll find the old german intros below.
Greetings go out to good ole Shaag and thousands of kisses fly to my beloved angel Julia! I LOVE YOU!!!

no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image
no image