TouchDesigner – 3D Tube Trails Custom MAT Tutorial – Atagen

demonstrates GPU particle systems rendered as 3D tube trails in TouchDesigner, using TOPs to calculate position and a SOP+custom MAT to render the tubes.

recommended you have at least a basic-intermediate understanding of TouchDesigner and GLSL first, but can probably be stepped through if you’re very careful.

apologies for the aggressive gating on the mic, hopefully there isn’t too much context lost.

more detail can be found on the interpolation method here:
https://mattdesl.svbtle.com/shaping-curves-with-parametric-equations

some corrections:

near the start I say X axis shows time; this should be Y axis.

I never actually used the “thickness” variable (which would be multiplied by our offsets with “dist” and used to adjust the size of the tubes without touching the SOP).

speaking of dist – if you use an odd shape instead of a tube this variable will keep that shape as its projected across the pseudo-tube. it’s fairly limited, but it works. just make sure to keep verts in 0-1 on x range, and have enough verts that you won’t get weird aliasing from inconsistent sampling of the position map.

feel free to ask for clarification below.

cheers, atagen