Dying Star VFX Production in Unreal Engine 4

Vidas Rimkevicius gave some tips on how to build a very pretty space-themed VFX. The whole effect is made up of 13 emitters all within a single particle system, it runs at a full 120fps, there are roughly 650,000 particles alive.

Vidas Rimkevicius gave some tips on how to build a very pretty space-themed visual effect in Unreal. The whole effect is made up of 13 emitters all within a single particle system, it runs at a full 120fps, there are roughly 650,000 particles alive.

Introduction

Hello! My name is Vidas Rimkevicius and I’m a Visual Effects artist who’s lived most of his life in the UK, having moved here at the age of 9 (now 21). I graduated from Staffordshire University this year doing a Computer Games Design course. I don’t have any in-house professional experience in the Industry as I’ve only worked freelance, but I’m hoping to find a permanent position soon.

I started off with UDK by doing some environment work as a hobby and even though I was very bad at it, I loved it, so when Unreal Engine 4 came out, I immediately bought a subscription to it. I didn’t actually even know I could work on Visual Effects in UE4 until halfway through my second year at University as there weren’t any courses for real-time vfx at Staffordshire University, so I only happened to stumble on Cascade by chance when we needed some fire in our group project game. I fell in love with visual effects and the possibilities instantly and haven’t looked back since. I’ve been teaching myself visual effects through youtube and just having a mess around with features to figure out how they work.

The inspiration for the Dying Star came from my University’s Discord Challenge, a suggestion flew my way for a big bang type effect. I’ve always been interested in stars so the idea clicked instantly, but I wanted the idea fully formed, so I searched for references of stars dying in any manner I could, and the blank spots were filled with imagination + trial and error. Luckily for me, I have people who aren’t afraid of giving me harsh critique, as without them, the effect would’ve been far less developed or interesting. 

Here are some GIFs of various stages within the development of the effect:

This is how the effect looked at the beginning. The effect primarily started with me experimenting with Vector Fields using the JangaFX VectorayGen software which allowed me to make some interesting vector fields for this effect. I used them throughout the effect and would highly recommend people interested in vfx to also experiment with them! Using them, I gave the effect a more ‘random’ look which is more interesting than if the effect grew and died uniformly each time.

I liked the idea of the effect pulsing from it’s core, but the pulses were far too visible when they spawn and overall, the effect felt weak to me as it had no impact and had basically nothing in terms of the ‘Wow!’ factor. So I kept at it, I sent it out to a few close friends for brutal critique (it’s the best kind!) and after they agreed that the effect felt weak, I started thinking of ways to build on to it.

At this stage I adjusted the way the pulses happen, rather than suddenly coming into existence at full colour, I adjusted their alpha and colour values to have them fade in over time instead. At the same time, I played around with the way the vector field grew out and rotated, as I wanted it to feel more like it’s ‘flowing’ with uncontrollable energy. To finish off the idea that it’s on the brink of destruction, I thought lightning was definitely the way to go.

Here I made the vector field neatly rotate at a low value, this creates the spiralling shape for the effect. To begin with, I was satisfied with it endlessly looping, but I decided that the effect, from a viewers’ perspective, would have a lot more impact if it has a finish. For the explosion at the end to work, the rest of the effect had to finish and lead into it smoothly. This was a tricky process and took quite a bit of trial and error with critique from friends to get the timing right. In the end I did this by making all of the emitters that are active for the spiraling star to stop after a set time, and shortly before they stop, the core collapsing into itself starts and then leads into an implosion > explosion type thing.

By this point, I was happy with the start of the effect and instead started focusing on making the end sequence as smooth as possible, the biggest problem here was that the explosion just didn’t have any *oomf* and it disappeared from vision far too quickly. I fixed this by adding 2 extra emitters with different strengths of the Drag module to add a few layers of depth to it. I’ve also rotated the core spiral vector field to be at an angle, it felt more interesting and dynamic with it and the explosion angled.

The whole effect is made up of 13 emitters all within a single particle system, it runs at a full 120fps throughout the entire effect and during the explosion, there are roughly 650,000 particles alive.

To begin with, the blue spiral sequence is made up of 6 of the 13 emitters, all organized and named appropriately so that I may return to them in the future and adjust them without having to work to figure out which emitter does what.
The blue spiraling is all done by a single emitter and I achieve this effect by toying around with the different modules provided. Aside from the actual vector field, the most important modules here are VF Rotation Rate at an X value of 0.1 to give the vector field a slow rotation, creating a spiral and VF Scale/Life for scaling the vector field relative to the particle time.

The second part of the effect is the initial explosion and then the red core collapsing into itself and flattening out. This is made up of two emitters, both of them have custom vector fields that I then either expand or squash. They use the same vector field but the explosion part is done using a much higher Vector Field Scale and Sphere Velocity values.

Using the initial explosion I wanted to highlight the instability of the star and to build up the anticipation for the final burst by adding a smaller, yet still large explosion that hopefully keeps people interested until the end.

The final part of the effect is the actual explosion itself. It is made up of the final 5 emitters. 3 emitters burst particles far outwards and linger for a long time using the Drag module to stop them and keep them there, each of those 3 emitters use different Drag values to create 3 layers of the final resting of the effects. They also use different values for the Sphere radius and velocity to make them travel different distances.

All of the emitters use a single material M_Radial_Ramp which I believe is one of the starter materials that come with a fresh new project in Unreal Engine 4 as is a simple radial.

As mentioned before, the core blue spiral is made using a single emitter and a single vector field. This effect took me a while to reach as initially I hadn’t planned on it spiraling at all, and I only thought of it after thinking about how an actual galaxy looks like. The vector field itself is nothing complex, just something to push the particles mostly outwards.

After adding in modules such as VF Rotation Rate to give the rotation, I’d add in the VF Scale/Life which allows the vector field to scale over the life of the emitter, allowing me to have a larger vector field over the lifespan. I will be making a video tutorial for this section of the Dying Star soon. 

 
The explosion of the effect initially started off with a single blast wave which was dull and lacked any impact, simply dragging the effect down. My line of thinking here was “if there’s not enough Boom.. Make more BOOM” so I added a few extra emitters to shoot out a very large amount of particles at different speeds, from different initial starting radius on the Sphere module and having different Drag settings, this basically gave me the effect I was looking for, but it disappeared too quickly. Here I increased the lifetime of these emitters and I added two new emitters that simply explode a little at the center of the effect. The lingering of the effect made it look much better and impactful than simply shooting off-camera and disappearing.
The lightning is identical to a previous tutorial I’ve made which uses a 2×2 flipbook texture sheet. However, the main change I made was within the ‘Required’ module. 

By enabling Duration Recalc Each Loop and Emitter Delay Use Range and setting up a delay and delay low, I have made it so that the blue lighting will spawn anywhere between 1 to 3 seconds after the previous spawn. Using this, I made the lightning less predictable. 

In my opinion, the biggest challenge for creating these sorts of visual effects is getting the ideas to work together. Of course generally you can find references to a star blowing up or images of a galaxy, but combining so many different aspects into one thing can be very tricky and can look terrible if not done right. The best advice that I could give for this would be to just have a blast with it, the stages I showed above are just a few of a couple of dozen different iterations of this effect. Whenever I make a change I’d consider fairly significant, I will send it off to a few friends and just see what they think, I always ask my friends to be brutal with critique, kind words are great to hear, but if a piece can be improved, I think it should be improved. Always keep in mind that majority of the people who are critiquing your work aren’t trying to crush your spirits, they just want you to improve, so don’t take critique personally, learn from it instead!

Vidas Rimkevicius, VFX Artist

Interview conducted by Kirill Tokarev

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