How can I make beveled curves transparent at ends (using bevel start and bevel end data)?

Folks, is it possible to use (beveled) curve data somehow so that the head and tail of the curve is transparent?..

I am making curvy beams of light (similar to lightsaber, but really long and curvy) that zip through my scene and I am animating the bevel start and bevel end, which works beautifully, but I really, really want the heads and tails of these animated beams to be completely transparent at the ends, and the transparency to follow along with the animated start and end values… So what is the best way one would go about achieving this, if it is indeed possible to do this? Pretty please…

I should probably add that I am using a Mix Shader with both Emission Shader and Principled BSDF shader plugged in, if that makes any difference, and rendering in E-Cycles…

Anyone?.. Anyone?..

We need some images to really understand the situation.

I really appreciate your help. I’m assuming that English is not your first language, but that question was articulated quite wonderfully, and it is a very simple concept… Here is your image. Thanks in advance.

You can start with this simple setup, using the ColorRamp to generate a mask for anything that generate the transparency (alpha, Transparent BSDF,…), then use driver to assign bevel start/end to the stops of the ColorRamp.

1 Like

Aaahhh… thank you so much! Separate XYZ was my missing link! And I did not even need a driver, because presumably the UV is stretched on the fly to the bevel ends (I had to use UV rather than Generated to get it working)… regardless, I am groovy now! Thanks again! : - )

1 Like