Hi again Andreas,
I have been looking the file and I see what you said about the problem of the iteration, is adding one list of numbers every frame. The other python node is very interesting, I see that is multiplying the idx number * 2, and that's how the width distribution is created. The problem is that my particles are not scaled in order by index... I think I gave you a bad example with the last c4d I uploaded..
I have uploaded the 3D scene, is done with Xparticles, I don't know if you have xparticles, there is a demo, but in case you can't download it I could send you a video demonstration.
With Xpartcles I created the system explained in first posts, also xparticles has some really cool nodes in Xpresso, with the XpIterator I get the index, with XpGetParticleData I get the radius of each particle (23)
I think the solution of compare current to last frame would be nice here, because the iteration number is not changing in the whole scene.(Particles are emitted the first frame, they don't die, no value change) Also I only need to activate it one frame, I could uncheck the xpresso enable after first frame if that would fit.
Sorry, I am trying to look at documentation and/or tutorials as well, but it's very hard to find easy examples to follow. But I have to say I am learning a lot with this examples you provide me.
Also, I see that is not recognising the XpTrail as a Spline (when I add the XpTrail to the Spline input) I think because this line "if not Spline.CheckType(c4d.Ospline)" and XpTrails has another nomenclature right?
I work a lot with trails and splines, getting this work would be really helpful.
(Can't upload the file, the size is bigger than maximum and it's not allowed zip files. If you don't mind, here is a link for download it https://we.tl/t-SduAyhaf6R