Lightsaber Burn Trail VFX

Building off of the Kylo Ren saber effects I had made previously, I decided to try my hand at making a dynamically rendering lightsaber burn trail effect to go along with it.

I noticed in most Star Wars games I had played, when the lightsabers were able to leave burn lines on the environment it was in set patterns limited to following the preplanned animation sets of the character. It was a really clever system, but every time I play a game with a lightsaber I have a burning (pun intended) need to get a dramatic shot of the player walking down a dark hall dragging their saber slowly along the wall, not just slashing mindlessly at random objects in the same 3 sequences over and over. So, considering I already had a lightsaber hanging out in UE4 to play with, that is exactly what I set out to build.

The effect works by running a line trace out from the saber and then projecting several layered decals onto the hit surface. These decals then fade out at varying intervals before destroying themselves to avoid any performance hits if large amounts of trails are created in a scene.

If a max number of decals is hit, which can be set via a parameter in the character BP, the trail will begin to more rapidly fade out the oldest rails to compensate and protect performance.

This effect is still a work in progress, as I'm hoping to expand and refine some hiccups in the future. The current drawback to this method is that the draw call for ray tracing in UE4 is actually not quite enough per second to get smooth lines on things like fast saber swings, so my next steps will be figuring out a way to route around this so the effect is seamless at all speeds.