About Mortal Kombat gore system
polycounter lvl 6
Hey Polycount,
So with the release of MK11 I started looking at the fatalities for some of the characters and was really intrigued by the gore system the people at NetherRealm have been using for their past few games, and thought maybe we could create some discussion and have someone throw some light about how it's made, because I think it's pretty interesting and I haven't seen it talked about here.
https://www.youtube.com/watch?v=UTo8rk9wUjM
I found a couple of old making off videos where they show how they mocap most of the moves and the basics for the system:
https://www.youtube.com/watch?v=4gGzddUro1s
https://www.youtube.com/watch?v=vXx7MckvtA0
I know a bit about some similar systems like L4D where they used shaders for faking holes or Metal Gear Rising with a dynamic boolean system, but with Mortal Kombat I think it's a bit different since you have to have into account the fatalities working with different characters and all that stuff and you have all those meshes being broken into different pieces according to the animation.
From what I understand they made meshes for interior of the body for every character and with different parts and modifications and those meshes appear in the scene everytime there's something brutal going on like a fatality or an Xray.
What intrigues me the most are the fatalities like the one from 2:53 to 3:00 or the one from 4:48 to 5:05 in the first video. How could something like that be made in Unreal for example? I don't think you can use opacity maps to fake some hole being cut into the body in those situations: you would basically need to have the character cut for that specific animation, but that can't be the case since there are going to be new fatalities being added and things like that, and then they would have to change how the characters are being sliced.
So, does anybody know how the fuck can something like this be done? Cause I really have no idea.
So with the release of MK11 I started looking at the fatalities for some of the characters and was really intrigued by the gore system the people at NetherRealm have been using for their past few games, and thought maybe we could create some discussion and have someone throw some light about how it's made, because I think it's pretty interesting and I haven't seen it talked about here.
https://www.youtube.com/watch?v=UTo8rk9wUjM
I found a couple of old making off videos where they show how they mocap most of the moves and the basics for the system:
https://www.youtube.com/watch?v=4gGzddUro1s
https://www.youtube.com/watch?v=vXx7MckvtA0
I know a bit about some similar systems like L4D where they used shaders for faking holes or Metal Gear Rising with a dynamic boolean system, but with Mortal Kombat I think it's a bit different since you have to have into account the fatalities working with different characters and all that stuff and you have all those meshes being broken into different pieces according to the animation.
From what I understand they made meshes for interior of the body for every character and with different parts and modifications and those meshes appear in the scene everytime there's something brutal going on like a fatality or an Xray.
What intrigues me the most are the fatalities like the one from 2:53 to 3:00 or the one from 4:48 to 5:05 in the first video. How could something like that be made in Unreal for example? I don't think you can use opacity maps to fake some hole being cut into the body in those situations: you would basically need to have the character cut for that specific animation, but that can't be the case since there are going to be new fatalities being added and things like that, and then they would have to change how the characters are being sliced.
So, does anybody know how the fuck can something like this be done? Cause I really have no idea.
Replies
https://www.youtube.com/watch?v=4gGzddUro1s&t=210
• As stated above, simple solutions are best. Look for camera cuts and close up shots as these are perfect for model swaps.
• Do not overestimate what the engine can do. This ties up with the first point (simple is always best), but also : UE3/4 can be a real pain when it comes to setting up assets. Poorly design interface with an oversized winamp-style look making every window look bloated ; very prone to crashing ; slow shader compiling, and so on. That of course doesn't mean that extremely complex stuff cannot be done with it, obviously
• Do not underestimate the resources that this studio has access to. They very likely have a team solely dedicated to the gore aspect of the game, with people (and tools) specialized in chopping up assets, repacking textures, and so on - a process that is very likely partly manual and partly automated. This is a very interesting topic actually, because they will indeed need to redo some of that work not only for new characters and fatalities, but also every time that add new costume skins/armor parts.
It's also possible that creating a new fatality (lets say, chopping off a character diagonally in a way that wasn't done in any of the previous ones) only consists of having two copies of the character in the scene, each masked off down the diagonal with an on/off opacity mask. And therefore the only content that needs to be added is the cross section of the gore anatomy/internals. Who knows !
• One thing you could do is to look at the Switch version of the game or the PC version at lowest settings. The lowres textures may reveal where the seams are, and so on.
https://www.youtube.com/watch?time_continue=470&v=EF-AgcihU1c
• Lastly, try to have a peek at the file names in the PC version. The game is not using regular UE4 hence Umodel will not work to extract models, but you may be able to at least unpack the files and look at the file names which may reveal how the models are prepared.
https://www.gildor.org/smf/index.php/topic,6598.0.html
Fun stuff
[edit] Oh btw, about the tech video just posted above : if I am not mistaken MK11 doesn't have X-rays, so that does simplify things quite a bit - putting the full focus on dismemberment.
@Obscura What documentary do you mean? I would like to take a look at it.
It from this series by Noclip maybe?
@pior There are Xrays when you get a counter and things like that now, instead of when you use the special attack that does a lot of damage, like it was in MKX.
For that kind of stuff I'm guessing they are using painted opacity maps maybe? Or maybe a postprocessing effect in an area that hides part of the body.
Also the problem too is that as you said there are a lot of cosmetics, and with that they would also have to slice them according to the animations. Since I don't have the game yet I can't confirm if they are cut with the rest of the character, but if that's the case that has to be a shitton of work.
https://www.youtube.com/watch?v=ECaM4fA3FmU
Which is really impressive to be honest.
While there`s some trucks they probaboy have to re-adapt/recycle shaders, effects and animaitons to different characters, I wouldn't be surprised to know that they entirely recreated motions, made differents SFX and geometry to fit specific characters...
They probably have some real time boolean geo-slicer/cutter (similar to MGS) and they fill the internal faces with some swell displacement shaders to simulate organs/guts.
Netherealms has really put the bar high in this game...
https://www.artstation.com/angel_bedolla
Seems like they use some meshes for most of the characters insides and probably swap the intact models for some precut ones then. Must be a pain in the ass having to redo the cuts to be able to add new fatalities and things like that then