member since December 21, 2009
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portfolio of
Felix Woitzel

Projection Mapping Controls

drag and drop control points a, b, c, d!

triangle a-e-f encloses the convex rectangle a-b-c-d
the relative distances of the 3 points on each border
are for uniform input float values for a custom shader
that, with the texture coordinate vertex attributes,
map a rectangle inside a single triangle.
triangles b-e-c and d-c-f are to be clipped away in the shader
open challenge: derive a solution that uses two triangles
for a continuous bilinear mapping and doesn't doesn't waste 1 pixel
that, or shader compilers do not run every branch either way

Fluid Simulation + Momentum Transfer +
Electrostatic Force

Mouse-interactive fluid simulation with particles.
The fluid simulation is solved on a 16x16 cell grid.
Using Verlet integration for the particle update.
Every particle has an electric charge and two of them have a static value. When any two particles collide, they equally share it. The border is the electric ground. There's a nonlinear friction and on every collision there's a tiny amount of 1% energy lost, so its passive state approaches a global lower limit energy.
So far, the binding of the forces is one-way only and the particle motion doesn't add to the fluid simulation.
Have fun!

Fluid Simulation

I took my old sketch and optimized it mostly for performance on Android. Firstly there's a simplified Navier-Stokes-solver (faster, but lacking in correctness) and secondly i have fixed an old interpolation bug.

There's no pixel access in P3D on Android yet and that's why i used Quads for particles. Retained mode wasn't usable for me either, but there's a Multitouch implemention:
The GL version is faster than software rendering for a few particles, but it scales worse.

The applet uses a simulation grid of 16x16 cells and 32K pixel-particles.

Rainbow Spiral

First, i wanted to make only a still image to print on paper and cut out as a toy for my 6 weeks old baby, but i went a little bit further and minified the code to 189 characters. :D

edit: i have included the final version for the papercut as another standalone pde file.
Print on cardboard for best results. ;)
(get the picture here too:

Lorenz Attractor [32k P3D Line

32k semitransparent P3D line segments equidistant on a Lorenz attractor trajectory.

If you have an Android device with compass support then check out the <a href="" target="new">Android versions</a>!

Lorenz Attractor [1k P3D Boxes]

1024 P3D Boxes equidistant on a Lorenz attractor trajectory

Fluid Particles mk II

I've added some finishing touches: 25x25 cells, 10000 particles, improved interpolation and framerate-independent particle velocity.

JS Preset Editor Beta

An editor for a js-sketch within a Processing-sketch. :)

I've been working on a script editor for Processing lately. There are multiple stages, from a run-once initialization section over a global per-frame section to individual animated waves. Only the per-point code for the wave-1 is set in the initial editor.

press 'm' to open the editor menu.
navigate to the active wave through the waves-menu and edit the code! Ctrl+Enter saves the changes.
Sorry, there's no documentation yet, as it is work in progress.

Pixel Pusher

I've grabbed an old sketch and spiced it up with massive particles.
Installable for Android: <a href=""></a>

24x24 cells, 8000 particles, linear interpolation

Color Cube

Processing remake of the original <a href="">example by Christopher Wolfram</a> for Mathematica.

This sketch uses parts of the <a href="">Tiny GUI sketch by Christopher Guebert</a>

Spiced Up Julia Fractal

This sketch is based on Kevin Bjorke's <a href="">"Spice Of Life"</a>
Only the original shader and the reset methods have been replaced.
Check out the huge performance improvements to the non-hardware-accelerated version:
<a href="">Mouse Reactive Julia Fractal</a>
This sketch doesn't run in the browser and you will have to <a href="">download the zip file</a>

Smoke Dynamics

A reimplementation of the Navier-Stokes equation solver by Jos Stam from the paper "Real-Time Fluid Dynamics for Games".

The original document is here to find:
(The zip file contains a copy too.)

This Java version is a total rip-off of the C code - Kudos to Jos!

Basic Fluid Simulator

A reimplementation of the Navier-Stokes equation solver by Jos Stam from the paper "Real-Time Fluid Dynamics for Games".

The original document is here to find:
(The zip file contains a copy too.)

This Java version is a total rip-off of the C code - Kudos to Jos!

Progressive Tree Fractal

Now this one is really slow without hardware acceleration.

Exponential Influence

beginning with basic functions for a composition of 2D differential equation systems.

Warp Grid

Using the vector grid for a warp transformation.

Uh! that's cool stuff - i have just accidently found a funny bug: open a second tab in firefox, so that the applet is running two times in your browser. It seems to be a shared (image) memory issue, but the resulting critter effect is pretty cool and demonstrates the true power of the warp feedback.



self-explaining, hopefully.
please comment if not ;)

Bouncing Balls

bouncing balls with some reactivity.
followed by

collections and classrooms

submitted sketches to:
Fractals & Landscapes
2D Simulations


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