- Hey, you wanna see something cool?
All right.
Hell yeah.
Nice.
All of those moments look good
and they feel even better, but why?
Animation and sound are important,
but there's something else that makes it all pop,
the secret sauce that gives us billowing fire in Mad Max,
messy explosions in Doom,
and whatever the hell this is in Control.
It's v effects, specifically particle effects,
and it's absolutely vital to making video games feel great,
and it's all a lie.
(dramatic music)
Or, maybe just a series of very artful deceptions,
smoke and mirrors.
(bell dinging)
Particle effects are an incredible example
of game developers using artistic and technical creativity
to overcome the limitations of their tools,
but precisely what the heck is a particle effect?
To find out, we talked to some of the masters
of the art form.
- To Remedy, visual effects are extremely important,
but visual effects allow us to build experiences
where the player gets feedback where they have very clear
understanding of the consequence of their actions.
- [Patrick] Mikael is a game director,
so it's job to make sure that the art direction,
the story, the gameplay, the level design,
and the sound are all coming together
as one cohesive package.
- We will start to create this satisfying, ratifying feel
that the game recognizes what I'm doing and responds
to the player.
It's fundamental for any kind of interaction
in any kind of a game.
- So, particle effects give you feedback,
but they don't just tell you what you've done,
they tell you exactly how it went down.
- I think a lot of what people associate with it
is the interaction between two things,
and telling a story of that interactions,
how powerful it was, how not powerful it was,
or the temperature of it,
or essentially, I would say the story of what that object is
and the properties of it.
- [Patrick] Precisely how an object reacts
communicates important information.
In a shooter like Rage 2, it can tell you if your shots
are actually doing anything.
- So, in a situation where you have
a very armored individual,
you're shooting at them, the bullets are hitting
and then sparking and flying off in a very distinct way,
when that armor pops off, then you get this sort of meat,
thunk thunk thunk thunk thunk feel,
so a lot of, the blood coming out has a relationship
with the health of that thing that you're attacking,
at least if it's an organic thing.
- These bursts of sparks, puffs of smoke,
and splatters of blood are all vital in communicating
to the players and making us feel good,
but how do they get made?
Particles are ephemeral and amorphous.
Their shape changes from moment to moment,
and that makes them really, really hard to render in 3D.
So, how do they make an explosion with real detail,
scale, volume, and depth?
They don't, but they do put an incredible amount of work
into faking it.
This is Oscar Bernelind.
If you meet him at a party and you ask him about his job-
- I usually say I blow things up.
- [Patrick] And he does that with the help
of particle effects.
- A particle effect, in its basic form,
is a physics simulation, where we then
put images on top of different points
that are physically simulated to create the sense
of giving a volumetric effect.
So, for instance, most explosions are just billboards,
which is just, it's a flat surface,
just a flat square that's being put on a point
and then being moved through space.
- So this is how games trick you into thinking
you're seeing an explosion.
If you saw it from an angle, you'd be able to tell
that it's flat, so to avoid that, the particles are
automatically oriented towards the camera,
and this solution works for all kinds of stuff,
depending on what we attach to these invisible points.
Attaching sparks to the points can make
a rudimentary bullet impact,
attaching alien goo can make a rudimentary blood burst,
and attaching confetti can make a rudimentary celebration,
but to really spice it up,
game developers modify the parameters.
How many particles do you want?
Should your particles get bigger or smaller
over their lifetime?
Which direction should they move?
Should gravity affect them?
How about wind?
How quickly should they fade away,
and what about the particles themselves?
Aside from still images, developers can use 3D meshes,
light sources, they can use animated images or flip books
to show the particle evolving over time.
By mixing and matching these variables,
v effects artists can make whatever they want,
smoke drifting up from a wreck,
dust shooting out from under a tire,
whatever the hell this is,
but back to explosions.
Avalanche's games are explosion-oriented,
so Oscar has made a lot of them.
His explosion recipe has three key ingredients,
the kick, the high point, and the falloff.
Each of these ingredients uses particle effects
in its own way.
As the name implies, the kick kicks things off.
- For the kick itself, usually we use like,
a flash of a generic shape or spark shape
or basically, you know, the cartoony ones
where you see it's going like, tsh.
Then we add additional sparks as well
to add more momentum to that.
- [Patrick] And they don't want the explosion to
look too perfect, so they add some dark grit
to break up the brightness of the flash.
Once we've seen that initial burst,
it's time for the high point.
- Which is, as the explosion grows to its full size,
this is where we get most of the kind of fire-smoke
interaction which is what most people really enjoy seeing,
such as from the Michael Bay movies.
- [Patrick] One trick that Avalanche borrows
from noted explosion pervert Michael Bay
is his liberal use of slow motion,
because real explosions move too fast for you
to appreciate the hypnotic dance of the flames,
so Avalanche's explosions move in slow mo,
while the rest of the world just cruises along
in real time.
Here in the high point of the explosion,
the evolution is the main attraction,
so to sell that evolution, they attach flip books
to the simulated points.
Flip books are 2D images but they're animated.
They do the complicated fluid simulations
in a program like Houdini,
and then they export a series of images
that they can plug into their particle system.
Played on its own, it looks like of like an animated gif,
but in groups together with subtle movement,
and rotation, and complimentary effects,
it looks like this.
Explosion.
You blow up a truck or a gas tank
and you get an explosion that looks big
and billowy and rich and it looks like
it has depth and continuous shape that morphs and evolves,
but once again, it's just a series of flat images
stuck onto points moving through space.
The illusion works, so it feels good,
but nothing good can last.
That's why we need the falloff.
- Just having a kick and a big mushroom cloud coming up
would look cool, but if then you just kind of,
disappeared, it would not feel as satisfying.
- [Patrick] We need to see the wind pushing the dust away
and smoke slowing down and dissipating.
- So, it's kind of trying to enhance that feeling
of it being something that's physical within the world.
- This is one of the awesome strengths
of particle effects.
They can be pushed around by the wind
or affected by gravity.
They can be attached to moving objects
and move with their own velocity.
This means every particle hit can feel a bit unique,
like it's a direct response to what you did
and how you did it.
Game developers tune their effects to make them look
and feel satisfying as hell, but those effects can also
tell us a lot of about the game's world.
In some cases, they can even help tell the story,
like in Control.
Your enemy is the Hiss,
an alien energy that corrupts reality.
It seeps into humans and fills them up,
and when you shoot them, they pop.
- It kind of strangely breaks the reality
as it leaks out, when you hit enemies,
so super gruesome, sorry about that,
but that's the kind of the idea,
that we are kind of dealing with strange forces
and resonances and elements that don't behave
in an expected way.
- [Patrick] To visually sell the idea
of these strange forces,
Remedy combines the very practical particle techniques
we've been talking about
with some extremely innovated post-processing.
That's where Elmeri's team comes in.
- So, we take, for example, an enemy and we take
information from the previous frame,
we re-project it from the position of the camera
in the next frame, and kind of draw this trail
of the enemy, but that would be boring to look at,
so then it gets adfected with the fluid simulation
and then after that, it gets broken into
the colors of dispersion.
- Okay, that is weird,
so let's try to break it down a little bit.
You shoot a bad guy, and an explosion
of Hiss mist comes out.
Like our explosion particle effects,
it's a bunch of objects stuck to invisible points,
but these aren't just balls of fire.
They behave... strangely.
The mist distorts time, everything you see through
that mist is one frame behind the rest of the game.
Then, they make that image wobbly and weird
using real time fluid simulation,
and then they apply a secret recipe of over-sharpening,
color filtering, and other little adjustments
to make something genuinely otherworldly,
something that sells the story that this vape cloud
from beyond breaks our reality.
From a story perspective, it's mysterious and weird,
but from a gameplay perspective, you still know exactly
what it's telling you.
The sharp tendrils of mist that shoot upwards
are a big blinking sign that says,
you got a headshot, good job.
You can fill a screen with explosions or dust
or reality-bending cotton.
The trick is making sure all of those things
look like they belong there and that they all
serve the game.
- Really adamantly make our visual effects
part of the world so that they fit in
and they blend and they get married to the scenes.
- Developers reach deep into their VFX toolkits
to make sure everything looks and feels right.
They're constructing an elaborate illusion,
and you know what?
Lie to me. (laughs)
I love it.
Look at this shit.
Yeah.
Hell yeah.
Nice.
(upbeat music)