Hi everyone! I recently added this lightning animation to my game and I was really happy with the results. I thought people might find it interesting to see how it's done.

My game has a bunch of different levels, and something i've prioritized during development has been ease of iteration on those levels, so a lot of time has been spent on tool development. This electricity hazard is a really good example of that. In engine, the "zapper" is just a path2d node (pic 2) w/ a script that generates all of the visual + gameplay components at runtime. This way, I simply drag the points around to adjust the zappers position, rather than having to modify all of the different visual components individually.

When the game runs, two different types of scenes are instanced based on the points in the path - the "attractor" scene which is the little tesla coil looking ball, and the "bolt" scene which is the electricity that jumps between the attractors. 

The attractor scene (pic 3) is just a sprite, a particle effect, and a couple of raycasts. the rays look for the nearest surface, and draw a line2d to make the support beam that holds up the ball end to that surface. I have the benefit of rendering my entire game on a relatively small canvas (480x270), so an extremely simple particle like the one on the attractor becomes much more dynamic looking as it moves around a low resolution screen and snaps to pixel positions.

  
The bolt scene is slightly more complicated. The bolts themselves are just line2ds, one blue and one yellow, which each have a series of width curves they swap between with an animationplayer. the width curves basically just fluctuate up and down semi-randomly (though it took a bit of tweaking to get the "look" correct). When you apply the width curve to the line 2d, it only samples the width at each point in the bolt, which results in this jagged looking lightning bolt effect. (pic 4 and 5)

The last step is to automatically generate those jagged lines in code (pic 6). This is simpler than it seems - basically i'm just giving the line2d its start and end points, and then adding some number of points evenly spaced along the line. then i randomly wiggle those points left and right along the line so there is some variance in the distance between the jagged pieces, and then i move each of the points away from the line a random distance and direction. 

All of this results in what i think is a really great looking effect that is also extremely easy to use as I develop levels.

Creating a fully procedural electricity animation