ofxFlowTools: optical flow, fluid dynamics and particles in GLSL


Hi Matthias,
Here Hugo from Mexico City. Everything start to move well with the code. I just have a question now. I want to use the force vectors in order to get values that could help me to infer movement of people. It may be a rude way but it may help for my purposes. There is a view in which you draw arrows. I would love to integrate the vectors and then, my hypothesis is, that I could get an estimation about the movement. I want to use such values to generate the panning of some sounds. If most movement if going left I generate panning sounds to the left. If most movement is going right I generate panning sounds to the right. Could you please help me to know where in the code I should start exploring?
Cheers and thanks


trying this addon on Linux I get a ofFbo:FRAMBUFFER_UNSUPPORTED error . I can’t get any clear solution . Can someone tell me what’s going on ?



The arrows are created with a geometry shader, so they won’t help you much.
What might help you is the getAverageFlow() method in ftOpticalFlow
This reads the optical flow texture into an ofVec2f array and returns the average value.
This method is quite cpu extensive, so you might want to draw (a part of the) texture in a smaller texture first and then apply a similar method.


Hi there, I’m instigated to test the new Mac OS Yosemite 10.10
Someone who has already tested, can talk about the experience? Is everything running well?
The migration of the Mountain Lion was easy for the Mavericks?




Hi, This is beautiful, but I’m having trouble getting it to run on Yosemite. The test app builds, but nothing shows up in the window. Any suggestions?



Hey guys,

I’m running it on Yosemite without any problem with the stable of version! With the master branch in github from two weeks ago I couldn’t get it to work but that had something to do with the new renderer (ofGLProgrammableRenderer), I got errors everytime I tried to use it in any project (haven’t tried the last version).

Anyway, this addon is wonderful, thanks Mathias!!! :blush:



Working without any problems in Yosemite here.


The last version is tested on yosemite and worked on a macbookpro (geforce 650m), a Mac Pro (firepro d500) and a hackintosh (geforce 760).
As long as you have a mac with a discrete video card the addon should work.
This also means the addon does not work on a macmini or any mac laptop with only an integrated intel video card.

Hope this info helps. Cheers!


This is incredible! Nicely done.

I’m trying to put together something for a party and would love to use some of this functionality. One problem I’m running into is that when I attempt to implement Syphon it doesn’t work! If I try to publishScreen it just spits out a black syphon feed. With Syphon it recommends setting up the window like this

//ofAppGlutWindow window;
//ofSetupOpenGL(&window, 1280, 720, OF_WINDOW);

But when I try that, then the application window goes black, too. Any thoughts? I can’t seem to figure out where the drawing is stored. If it’s in a texture somewhere, I could use publishTexture, perhaps.



@aaa The current ofxSyphon doesn’t support the programable renderer (i.e OpenGL >= 3.2). Check the info in this pull request, that gives syphon compatibility with modern opengl.


Adding Syphon to ofxFlowTools

if you remove #define USE_PROGRAMMABLE_GL in flowToolsApp.h it runs in OpenGL 2.
fluidSimulation.getDensity() returns the density texture, a.k.a the color texture. Note this is a float texture (GL_RGBA32F) and i’m not sure ofxSyphon supports these.

Adding Syphon to ofxFlowTools

Curious as to why performance on Windows is so dismal…I am getting only 7-8 fps. Is flowtools tied to OpenGl?


yes it is.
I recommend using a Mac.


Hi there,

I saw the demo in the vimeo and it was super!
Tried with my environment(Xcode6.4 and of0.8.4) and succeeded to build. However the particles don’t seem to appear.

Sorry I’m a little nonsense but if you give me an advice, I would be appreciate you.



FT has some troubles with the blendmodes, especially on windows.
just to be sure, what os do you use and what graphics card?


Thanks for replying m.oostrik!
I’m using a OS X Yosemite(10.10.5) and using Intel Iris Graphics 6100 1536MB.


The 6100 is not a discrete graphics card, although it is probably powerful enough to handle the flowtools I have now way of testing it.

How does it handle draw mode 4, the Fluid Fields?


I’m using MacBook Pro Retina 13.3inch 2015 so it should have enough spec I guess.


That visualisation also does not do what it is supposed to do (unless the simulation is empty).
I’m sorry, but I am afraid i cannot help you with this problem at this time.


@m.oostrik @moostrik Love the add-on. I’m trying to use an easy cam as the source instead of the laptop’s video camera but haven’t quite worked it out. Any suggestions?