Blur effect doesn't render on transparent background. Help needed.

I’ve trying to render a lightsaber on a transparent background to use as sprites on a project of mine. I’ve followed a tutorial on youtube to create the glow effect and it worked great on a black background but it’s completely invisible on a transparent background…

I tried to look for a solution before making this topic. I found somebody else who had the same issue but I’m not able to follow the instructions given in that topic. I know it’s English but I can’t make any sense of it. So I’m hoping that someone can find a solution for my situation in particular. Any help is greatly appreciated!

Node setup


red_lightsaber.blend (966 KB)

Hmm, it seems like mix nodes can’t use blending modes over a transparent background.
You can use a black BG for the glow and render it seperately from the handle. Then whenever you use wan’t to use them in a compositor you just set the glow layers blending mode to add.
Really not the best solution, but it’s the best I can think of for the moment.

This topic was accepted almost 24h later and in the meantime I figured out a way to get a decent result. The node setup is quite entangled and probably with redundant nodes but I’ll leave a screenshot of the setup here in case somebody will come across the same problem.