The Sacrifice Devlog 007: The Cultists (20/01/21)

The cultists are in and all vfx'ed up!

Here's the sequence as is:

So far in the scene I've just been using normal skeletal meshes however I've now set up a very basic animation blueprint that allows me to have them raise from a praying position, into a sort of worshiping pose. It's just a blend between the 2 animations, but I have them raise so fast it works well enough.

I timed the raising to happen as the portal snaps open, with each row slightly later than the last to make a wave motion, it's very quick but adds a bit more than having all the cultists raise at the same time.

With the mixamo animations set up, I started work on the soul effects. I broke the effect down into a few stages, being: initial poof, soul leaving, and the cultist body fading away.

For the first initial poof of energy I wanted a fast and impactful poof of energy to come from the cultists face, as to signal something is about to happen. I time this effect to happen on the next beat of the cultists raising wave so it feels consistent and like the next natural step in the sequence.

The next stage is the soul actually leaving the body and flying into the portal, spiraling through the air on its journey. To put together this effect, I looked back at my soul moodboard and went to work creating a texture for the head of the soul. I made the texture to taper off at the bottom so the head sort of fades into the trail forming one consistent soul.

After this, I went into substance designer and put together a trail texture using some built in noise and warp nodes. I then set up a material in engine that pans and tiles the texture, applies some alpha erosion on the end and then colours using a lerp node.

Beyond the materials, for the particle systems I set up the head of the soul to be velocity aligned and use a vortex force with a point attractor to pull the particles in a spiral towards the portal. The trail then just uses location events to follow the particles.

I also set up the blueprint that controls the whole sequence to delay the soul effect randomly for each cultist, as to prevent all the souls from leaving at once and feeling a bit static. I also had a problem where I'd get 2 souls spawning for each cultist, however I fixed that by extending the loop time of the emitter. Not sure why that fixed it, but it did so I'm not gonna complain.

Finally, I wanted the cultists to have their body sort of dissolve. To get this effect implemented a technique I saw be used as part of a fake volume of water shader, which allowed me to create a mask on a mesh in worldspace, as though it was being projected. The idea behind this is that you take the pixel location, subtract the object location, then subtract the object bounds. You can then multiply the object bounds a re-add the result, to control the amount of the mesh that's masked. In my case I went with a Z axis mask going down from the head of the cultist mesh.

From here I just applied some alpha erosion, smoothing, and coloring, and my cultists could now dissolve out of existence!