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NVIDIA FleX 1.2 solver integration in TouchDesigner as a CHOP

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Look at the Releases page for the compiled dlls for Windows.

NVIDIA FleX 1.2 solver ( integration in TouchDesigner as a CHOP with a limited feature set : * liquid particles only * collisions against primitives : planes, boxes and spheres * collisions against a single animated and deforming triangle mesh * simple disc and rectangle emitters

A NVIDIA graphics card is required since this uses the CUDA version of the library. Geforce 1070 or better recommended


Sample Toe files for TouchDesigner 099 are provided. demo.toe : emitters and collisions against primitives demo_torusCollision.toe : collisions against an animated and deforming triangle mesh Shift-R will reset the timeline to frame 1 which is set to reset the simulation in those examples (Reset parameter on the Chop).

Most parameters on the FlexCHOP are parameters of the solver, please refer to the official FleX documentation at for more information. FPS determines the timestep of the simulation, higher FPS than TD FPS means the simulation will run in slow motion. There is a fixed maximum number of particles in the simulation, after the number is reached, older particles are recycled in new ones.

Emission and primitive Collisions are handled using CHOPs, with one emitter/collider per chop sample. Refer to demo.toe to see which channels are required (channel order is important)


To compile with Visual Studio 2015, download the FleX 1.2 library from (you need to get access here first and put the directories in a flex folder at the root of the repository (you should have flex/bin, flex/core, ... alongside CHOP/Source). You also need to manually copy the flex .dlls (NvFlexDeviceReleasex64.dll, NvFlexReleaseCUDAx64.dll) from flex\bin to CHOP\Source\Release or the FlexChop dll will fail to load.


This is provided as is, mainly as a starting point for people interested in extending TouchDesigner with external c++ libraries. I have an ongoing TOP implementation in TouchDesigner, more optimized and with a more complete feature set which was used on a few projects of mine, such as Fluid Structure ( and lull, with AV&C (

Change Log

11/13/2019 0.4 : added support for collisions against a single animated and deforming triangle mesh. For TD 2019.10000+. To get the plugin to load with Experimental, copy cudart64_92.dll from TD 2019.10000+ alongside the other dlls. There is currently an issue with the GLSL shader for the instancing.
09/10/2019 0.3 : Upgrade to flex 1.2
09/10/2019 0.2 : Upgraded to work with 2019.14650 and later series of TouchDesigner (Spring 2019 Release), and be usable as a Custom OP. Thanks to Malcolm Bechard for the upgrade.
09/29/2017 0.1 : initial release, flex 1.1 library

Vincent Houzé

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