Trail & Impact VFX Production

Guillermo Rossell did a breakdown of his trail VFX Twi-Finisher made in UE4, talked about trail and impact VFX production and gave some advice for those who want to learn VFX.

Introduction

Hello! I’m Guillermo Rossell, I’m from Lima, Peru, and I’m a VFX Artist. Among other projects, I’ve worked on a VR game Stage 3: Azaria.

I got into game development when I was 22. At the time, I was studying informatics in the institute not knowing what to do with my time or life until my friend Mauriccio told me about game development and how amazing it’d be to start studying it to make our own games. This career is almost non-existent in Peru, so we had to search for online tutorials and work our way up there. At the same time, though, I started learning 3D modeling.

Eventually, we founded a videogame studio and started making our own projects in UDK, but due to the size of our team we had to distribute work and were not able to specialize in only one thing.

It was then when I started doing VFX alongside 3D, and suddenly everything clicked with me. I remembered some time ago when I used to play Aion or Granado Espada, and I’d be looking forward to each level up, but not for the stat increase or the new armor, not even for the new skill bonuses, but for the animation and looks of these new skills. I was absolutely passionate about it. I’d level characters to max only to see all the skills and then would do the same for every class.

After that discovery, I found myself playing with Cascade way more than I should, and it was decided I’d drop 3D and focus on VFX only.

Twi-Finisher VFX

Building a Trail VFX

Lately, I’ve been practicing trail VFX quite a lot. Playing God of War 4 and watching the trail VFX for the Ice attacks, I was inspired to create my own take on those mesmerizing effects.

Before starting, I’d advise finding a good slash animation to work on. You could use any animation to make your trails, but I find it more inspiring if I can find animation with a full swing and a lot of punch.

The way it works is that you need to choose two points from where you want the trail to appear. I usually create 3-4 extra virtual bones on my skeleton just for my sword trails.

Before you’re done creating the material for AnimTrail of the particle and hooking it on the animation, you need to make sure the flow of the material matches the swing and direction of the animation you want to go for.

Once that’s done, you also need to time it and make it appear when the slash starts gathering strength or momentum, and make it finish when the said forces have started to wither.

Usually, I iterate step by step watching the animation play. Sometimes it’s better to speed up the panning speed of the material, or the intensity of it with the parameter curves inside of cascade, as if you’re always looking at a static material (texture). Panning only won’t do the trick, and I always try to make my particles following one principle: they must have a buildup, climax, and aftermath moments, so the trail (or particles) look alive and in motion.

For the Twi-Finisher VFX, every emitter of the particle system has its own buildup, climax, and aftermath (BCA), and combined they form the whole BCA of the particle.

Just as I mentioned above about the particles following that principle, I try to apply it to my trails as well by making two different trails merged in one, so I can control momentum, for example, by adding a core to the trail, or a veil around it.

UE4 makes it very simple because I can just add more notify tracks that can merge into one later on. Those three-four extra bones that I create near the sword help me control the trail even more, as I can choose where X trail and Y trail will spawn.

Particles

I had a blast playing with the spark particles around my trails. You can make them float, or fly at high speeds that stop after a certain amount of time.

The modifiers that were vital for my experiments and for particles that fly away from my trails, were acceleration/over time, drag, orbit, and size by life. All of those help you animate your small particles so they feel alive, vivid.

If I’m looking for a trail that depicts speed and power, then my sparks will start elongated and will transform to a dot over time. On the other hand, if I’m looking for a magic trail, perhaps my sparks will remain a dot all the time. Of course it all can vary, but usually, I handle it that way.

VFX Adaptation

For me, the most difficult thing in an adaptation of a VFX to animation and character is capturing the character’s essence within the effect, so that you could look at it alone, and know it belongs to him. For example, our protagonist may be a Dark mage, which means he controls dark magic. What if it’s forbidden? Maybe he has no control over it, or maybe the energy overtakes him. Knowing that the VFX animation could be unstable or a heavy burst of magic can be involved. If it’s forbidden, then maybe ancient-unknown letters may appear when he casts it, and so on.

Something I struggled the most in my first personal project was how to stop making my VFX visually overpowering. I loved to make big particles and explosions! But after some time, I learned that in order to make a big explosion VFX, first there must be animation and a moment according to it. For example, if I want to make a huge impact VFX like the one I’m showcasing, I can’t flood the moments before the impact with lots of VFX like waves of light following the character’s weapon. I’d rather leave it clean, waiting for that big hit, just like in a movie when everything goes silent before something bad is about to happen.

Then, you also need your animation to go along. A simple attack on the ground can’t leave a huge hit VFX (unless lore says he’s an overpowered overlord), that’s why our Feng is jumping in the air gathering all his strength before impacting the ground with his weapon.

Impact VFX

Let’s dissect the impact VFX.

For the impact VFX, I always start with the impact on the object the effect has been applied to. In this case, with the “cracks”. I wanted it to be a magic impact, so I chose to make energy flow and then dissipate between the cracks of the impact, and also energy “EnergyT” flying in all directions due to all the power evoked by our character while hitting the ground.

Even if it’s a fantasy-theme VFX, without adding some realistic effects it’ll look unbelievable, so I added rocks “DustStone”, “DustPiece” and dust that would come from the ground.

We also have a group of shockwaves and smoke to make our impact believable: one is a white-power shockwave, and the other is the main focus of the game, which is the lightblue-centered one, and it packs a lot of punch in color and momentum.

Last, there’re the small GPU particles: one emitter spawns particles that spread evenly in a horizontal pattern (making the impact seem more believable) and the other flies upward and then stops, floats, and remains there for a longer time than the rest, helping the effect seem more magical and more important than anything. It helps to sell the idea of “these are the remains of a powerful attack” or “something big happened here”.

Advice for Learners

My recommendation for people who want to learn VFX in Unreal would be to watch the ImbueFX tutorials on youtube. The teacher is excellent, and they’re free! If you can afford some paid content, I found this Gnomonvtutorial to be excellent for starters.

As for UE4 materials, my recommendation outside of watching tutorials would be downloading free materials (Paragon, etc.) or buying some VFX in the marketplace and study how they’re done.

Guillermo Rossell, VFX Artist

Interview conducted by Kirill Tokarev