Creating the Flood Effects in Uncharted 3

[Music] okay let's do this [Music] oh [Music]

[Music] well we had a lot of water on Uncharted 3 um this talk is about creating the flood effects in Uncharted three um e and cook I work at naughty dog um a little bit about me uh I've been in the industry for about 11 years um most of that has been at um Electronic Arts working on Metal of Honor and then naughty dog working on the Uncharted series and now I'm working on the last of us our new game uh Naughty Dog uh which looks really exciting um let's see uh before all that I studied graphic design um with a minor

in computer science at the University of North Texas and uh that computer science minor is becoming more and more valuable uh as a effects artist in games um and I think it's going to continue uh in that direction for sure so in Uncharted we did lots of kinds of water we did puddles we did waterfalls oceans and floods is what we're going to talk about today uh first of all I just wanted to give a shout out to the Naughty Dog Engineers because they really do an amazing job at um eeking all the performance out of uh the PS3 that's possible and uh we really couldn't get the the level of visual quality that we get without their amazing work so first shout out and this is the effect we're going to be looking at today with no

so as an artist I look back on this and I still just feel like there's something missing it's kind of hard to put my finger on it but oh maybe it's Subway sandwich $5 foot long um so to make the effect we started with a fluid Sim we did a pretty coarse fluid Sim inside of Houdini uh and we were able to iterate pretty quickly and um use it as prev visualiz ation to work out timing and the flow and the amount of water and um all those details um pretty rapidly uh without having to go uh back and forth into the game um but it wasn't just for PR visualization we ended up using it um throughout the whole production of the effect uh we created the the in-game mesh from the simulation um we also us you know looked at the simulation um for insiration on

uh like where the particles should be spraying and uh the direction and speed and all of that um and then finally we we used the actual Sim data to push the rigid bodies all the um debris in the hallway all the boxes and things uh those are pushed Along by the actual Sim data and since the mesh came from the Sim data the particles were inspired by the Sim data and then the rigid bodies were pushed by it it all kind of comes together and it matches um so to create the mesh um we had uh we had to figure out how we were going to do this because the surface obviously has to morph constantly um we considered possibly doing a point cache but uh quickly rejected that idea um because it would require a lot of new tech that we just didn't want to invest the time in in building um we did a first attempt uh

which um was more programmatic and parametric in nature where it was allowing us to basically um Glide bumps across the surface uh we abandoned that because it was very uh hard to work with as an artist and uh we just couldn't get the level of fidelity that we wanted um and so we decided to go with the brute force method which was essentially to do um skeletal meshes uh because our engine supports skeletal meshes really well um and to do one joint per vertex um the engineers actually were able to uh increase our ver our joint count to about 580 joints per mesh um which wasn't quite enough to get the entire flood but uh I I'll cover that in a bit um in order to optimize uh

fortunately we had sort of a fixed camera angle we knew that the camera was going to be tracking away from the flood itself looking back at it and so instead of uh using a a mesh of squares um I elongated those um so if you look at it top down they're actually rectangles uh which allowed me to cut out about a third or 2/3 actually um of the the points and therefore the joints uh that were going to be required and when you're looking at it head on because of the way perspective kind of squishes it all it looks like a uniformly covered mesh so we used a ray casting method to um to uh kind of extract a surface from the fluid Sim uh this was also done in Houdini um but sort of the default um way that you would do a ray cast is to just cast along the normals of the surface and in this case that would be

just going completely vertically up and uh that was going to cause some some problems some artifacts that we didn't like um and so I experimented with casting the Rays more in the direction of the camera and uh that actually solved a lot of our problems um so you can see here with this diagram that um casting Rays along the normal uh uh in that striped area that's that's creating an error where um there's meant to be an overhang but there's actually just a wall and the camera is looking you know right at that and it looks horrible so changing the direction that we're casting from to face the camera a bit more it reduces the errors altogether because of the way the water is kind of shaped but um also the errors are more hidden from the camera so that really helped the look so like I said before um uh there

were more than 580 points required for this Hall flood so had to actually like make three separate meshes um that were all driven by their own skeletons um and because uh that gets a bit tedious to work with um I created a a little tool that would allow us to um uh treat the entire surface as one thing even though it's in the game uh according to the game data it's actually three separate things um and uh it allows us to build it all as one thing and it really cuts down on the iteration time uh it's not as important on this one because it was only three meshes but we Ed this technique um in other parts of the game including like in some sand simulations with flowing sand and uh it became more valuable there because some of those surfaces were like 12 to 14 separate patches uh

which would just be insane to to iterate on if you were doing it all by hand so here's what it looks like with just a surface and no Shader on it it's a little bit dark on this display but you can see a little bit how it's morphing so the surface Shader we use the um sort of our standard water Shader that we used uh throughout the game and other types of water uh it's a really big Shader and it has lots of features but these are some of the relevant ones for this effect um it does refraction which basically takes a copy of the screen buffer and it distorts the UV lookup based on uh the normal so the normal will uh change where it's going to look at the the screen texture uh and then also the depth so the deeper the water is the further away from

uh the um screen pixel that it would show without refraction uh the further from that it gets so it gets more distorted the deeper it is and then there's also um opacity based on depth that helps it to look like um there's particulate in the water uh so where it's deeper it gets more opaque um and then for reflection um the surface changes so much and it's it's anything but a flat plane so doing real-time Reflections wasn't really an option but the cube map uh was totally adequate so we did that with frel to um make it a stronger reflection on glancing angles sort of standard reflection stuff um and then uh lastly we did foam on the surface um which just kind of helps it look a bit more turned up here it is with

the surface Shader so it lacks it really lacks a lot of the visceral quality that it needed to have um if you wanted the player to feel like uh he's really being chased away by this giant Deluge of water so um that actually came from the particles um particles ended up being just the the real um the really important part of the effect the surface was sort of secondary um we ended up doing 31 separate emits that were all uh hand key frame animated um to match the animation of the water and uh eight different particle definitions so eight different types of particles that those emitters were emitting so we have a at NAU dog we have a really uh great tool set and uh run time to go along with it um it's our um UI is all done through Maya and we share

a lot of the same features that um Maya particles have um one thing we can do that's really useful is create custom attributes so we can store off any kind of Uh custom data that we want um and we can we can give those data values uh using Expressions expressions are huge if you're unfamiliar with Expressions you should get familiar with them and um beg your programmers to uh add it to your tool set cuz it's it's super flexible allows you to um to manipulate data uh pretty much any way you want um our expressions are really similar to Maya's Expressions uh we can even piggy back off of Maya's like um syntax error detection and all that um so if you know my Expressions you pretty much know naughty

expressions and then we have the ability to use ramps um create gradients basically and um we can use our custom attributes as indices into the ramp so we can pick where on the ramp we want to pull a a color or a value um using the custom attributes and we can define those through Expressions so it all comes together and gives you a lot of power and then we can also send these custom attributes to the Shader uh which allows you to further um control the way the effect looks by controlling Shader attributes and stuff like that um so it's all very powerful and then one of the other cool features I mean there's a lot of them but this is just one last one I wanted to mention is um custom orientation so our Sprites don't necessarily have to face the camera and they don't necessarily have to be velocity aligned uh we can use our custom attributes and

Define vectors that will Orient the particles any way we want super flexible it's really nice and all of this is due to Marshall Robin uh he's um pretty much the loan programmer at n dog who does all of the effects stuff he's really incredible he has a talk today at 2:30 in room 309 so go to that if you want to learn more about Uncharted effects from a more programmer technical perspective so um as every game affs artists as aware fill rate is the Enemy Number One so we do do a couple of things to um get around the fill rate problem and allow us to draw a lot more particles uh which in this effect gives it the really full like frothy look at the the front of the wave uh we render our particles to a quarter res buffer so

um already we're drawing one qu of the pixels um so that's a big gain and then uh with most of the effects that we do they're roughly round shaped um and the corners of a quad are usually completely transparent so we just chop them off and make octagons instead of quads and it's a good tradeoff um between number of points and uh number of pixels drawn because pixel we're usually fill rate bound so that's a a really nice win as well so um the main particle that you notice in the effect is the froth particle uh this these are the color and Alpha uh Maps used for the froth particle uh they're based on Source photography done by a colleague of mine at naughty dog named iy ikram he's a great photographer I love photos by ii.com

um and then to get more variation uh we had four um different uh looks and just the color and Alpha and then to get uh more variety we just um smush around the UVS using this color texture map and then the other main feature of the the Shader is um Sparkles before I added the Sparkles it really did look like flat dry cards um it still had a real um Lively motion to it and stuff like that but it didn't really feel like water um but just adding a little glints of light really helped a lot and that was achieved with this um on the left the um it's like a black field with sparse white dots and then that's multiplied by a uniform noise that scrolled across it and it ends up just making it twinkle basically so um the quarter res buffer um buys us

a lot um back in terms of uh fill rate but um it also is half or a quarter of the resolution so it's it makes things look a lot more fuzzy so to combat that um I did custom M Maps I took the um Alpha and the color texture into Photoshop and down sampled using nearest neighbor uh filter ing which gives it a much better histogram the the lower image the lower Standalone image is the nearest neighbor sampled one and the top one is is a bilinear filtering and uh you can see that there's just higher contrast and a Sharper Image uh so I recommend doing that if your if you your engine supports it um this is what it looks like inside our previewer our material previewer um one thing to note is that the sparkles on this the scale of them is not correct that's because um

the scale is controlled by a user variable that's passed from the particle so when I was showing you the particle UI and you had the ability to pass data to the Shader that's this is one of the things that's affected by that so when you run the effect in the game the Sparkles are uh smaller not so big and Blobby so Keith gett um he was the lead effects artist on Uncharted 3 and he's doing a talk that'll cover more of our um t uh techniques and tricks uh that we use for shaders if you're interested in that so go hit that one up so here it is with just particles so particle lighting turned out to be really huge um it really sits it into the environment and gives it depth and uh the color variation that makes it look much more realistic um you

can see it looks really flat without the particle lighting first thing to know about the lighting is that it was a hack um we didn't really have good lighting techniques for particles in Uncharted 3 we basically used a lot of hacks um this hack was um using two ramps one ramp ran the length of the hall um so the darker area at the top is sort of the back recessed area and then the the light spots are where there's um light and the hall shining on it and then one cross the width of it and the two are multiplied together and it basically makes sort of a low reses looking texture uh and that's projected down straight down onto the particles and the wonderful thing about this was that it was all done with existing Tech uh we didn't have to go to programmers and and ask them to implement this kind of lighting which is sort of a pseudo light map kind of technique um just with the flexible tool that we already had we were able to come up with this idea and

implement it without any programmer support so here's the final image with lit particles and that's pretty much [Applause] it so naughty dog is hiring uh Candace Walker I think she's going to be outside the room you can check with her um If U see if there's a spot for you uh there's another shout out there and then of course I wanted to thank all of you um appreciate you coming and I wanted to mention that there is um a mobile evaluation uh and check your spam filter and your email to make sure that you get that and fill it out um and at this point I can take a

couple questions there's a couple of mics if you have questions please step up to the mic hey awesome awesome talk um question I have is um Houdini is used a lot in film effects a lot of game guys um these proprietary engines what sort of took you guys down that right did you hire someone who was a Houdini expert or did you guys um train in it uh basically between Uncharted 2 and Uncharted 3 uh I started learning Houdini because I I knew how flexible it was and and how um sort of a more technically minded artist can actually make really useful tools and stuff like that so I started learning that and then put it to use in Uncharted 3 it was basically just my call it was a little hard to convince them to to Shell out the money for it cuz it's really expensive but we got over that

hurdle hi um what was the uh purpose for uh taking the uh over here sorry uh taking the fluid from Houdini into Maya was that just uh because of the pipeline that you guys had for uh The Joint placements and all that yeah actually um uh it was a little unclear I we did the fluid Sim in Houdini and we actually created um the mesh with the mesh animation inside of Houdini brought that mesh over we left the fluid Simon Houdini brought the mesh over with its animation and then that tool that I was showing that I created also like adds all the joints at all the points and sets it all up to be used in the game okay um I will be outside to field more questions um just wanted to mention that this will be in the GDC Vault um