Abstract Fluid FX In Houdini | Pro Karma & Houdini Tutorial

hello and welcome to rway my name is s jesi and today we're going to go over the creation of this awesome face Splash effects as well as rendering using Karma and material X it's going to be a two-part tutorial the first part I'm going to go over the shading and render and rendering and explain how the UV uh technique works and the second part is going to be taught by my colleague Andrew Southerland who's going to explain the simulation process in depth thank you so much and let's get started all right so let's take a closer look at this so what we have here is a flip Sim uh emitting fluid in the first few frames and then that fluid is then dropped onto this face and with the retiming of the solver we can get this nice slow motion effect and there's also viscosity and all the tension features to get the nice tentrails and stuff and so with flip or with any uh tricky Sims like this it's hard to get a nice UV coordinate that is uh that flows along the mesh nicely and so we we have a simple uh trick for this that should work in even more complex scenar is and this is the flip Sim it's coming in here and we turned off proceeding so we have a um we turned off proceeding and also the all the points get emitted in the first few frames which should be fine but the P Point C doesn't change that much uh throughout the Sim and the other thing is we have an ID attribute so that's very very important for this technique to work and when um when you think about it I mean there's few frames that we could use where we want the UV coordinate or the UV textures to be perfect and let's say at frame 30 we like everything about the Sim and we want to initialize our UV coordinate and that frame so here we have um I'm using two different frames to create two different UV coordinate that I can use and um going to go with this one so this is the one I used I believe so it's frame 30 and the idea is to create a UV coordinate so we just place a a planer planer projection here and apply UV coordinate on that and if I use a if I use a UV quick sheet and visualize this think it's going to work on points yeah it's not going to work on points but if we uh create a UV coordinate at this position and then mesh the surface and transfer this transfer the UV coordinate to the mesh we should be able to get something like this second so we should be able to get something like this so that's our UV coordinate being displayed with a texture on the mesh and because we have an ID attribute I can use I can use this frameold here and copy this UV coordinate back onto the flip Sim so if I go backward to frame 20 let's say I am going to uh basically reverse the animation and still inherit the frame 30 UV coordinate and you can see how it's staying uh it it's working backwards basically so at frame 30 it's going to be perfect but everywhere else it's going to be stretched and because we use a a frame somewhat in the ble we should be able to get nice stretchy effect throughout the entire Sim and the idea of using two different frames is that if it the first one is too stretched and you are using a different camera you have an opportunity to pick a different one so the one I'm interested in is copy it to the to the mesh uh using by respecting the ID attributes so from the point to the flip Sim sorry from frame 30 to the flip Sim and then when we mesh the uh the data we we we keep that information so here I'm just visualizing that we also have an ID sorry a color attribute on the mesh that's been uh that's generated based on a noise from the rest attribute so because we emit all these points at the same time we give them a rest attribute and that is being used to drive this so I use two um two things to generate textures I use this map here which I'm going to remap and also the UV coordinate so let's go to the uh stage I'm not going to rebuild this from scratch because it's fairly fairly simple and let's make sure we're looking through the the right camera so here I'm importing the the flip mesh and this is the camera I created couple of cameras and here I have Sky using a default hdri texture that comes with Houdini I have an area light from the bottom and sorry a fill and then a key light from the top to create that the majority of the lighting here and then the Shader is just a material X which I'm going to explain in the next video so continue there in a bit all right so let's take a look at the Shader so what I have here is a standard material X so you can just create a standard surface and this is the default and what I've done is I imported the color attribute so we use a material X geometry color so there's a node and it's going to look up the CD attribute right away but because of the naming conventions we don't have to worry about that it's just going to if you have a CD attribute it's going to work you don't need to worry about anything there and I'm plugging that through a color correct to um increase the gamma and let's say I'm plug in that here straight into this ramp I'll explain what this is in a bit and I'm running that through a rem map to just get more details into this black and white map and then this will go into another one to give it uh random colors or actually driven from this map and then I'm using three variations of that one for the diffuse one for the transmission color and one for the subsurface color and each time I'm just changing the Hue uh the saturation the gamma and yeah the saturation again just to create variation in in the layers now the second part is adding or generating an A A noise based on the UV coordinate so here I'm importing the UV coordinate that we created in softs through a geometry prop property value so I'm going to create that tial X geometry property value and you can type in whatever attribute you want so in this case I'm using Vector 2 and I'm importing the UV and I'm plugging that into a unified noise 2D and this is the material X node and then that goes into the bump which is connected through the normal and I'm also adding that to the colors so I'm adding my noise to the color so we have I have more variation uh in in my texture generation and that's pretty much it I have some um a transmission here so .7 I have some Sheen to create some sort of fenel or velvety look and then some subsurface uh uh with a small very small radius to get the subsurface effect I'm going to try to render this so let me switch to the camera let's move to the camera and this should work uh perfectly fine with the karma xpu as well so I I don't have nice GPU so I I use CPU for now I'm going to switch to Karma CPU and there we go you have our Shader and we'll Supply this file with the um with the geometry of this still frame maybe frame 60 and you guys should be able to replicate this effect if you wanted to render this with XU or explore anything with the render honestly all right thank you for watching and talk to you soon bye-bye hello everyone and welcome to rebelway my name is Andrew Southerland and today we're going to be creating the small scale fluid simulation I'm going to be covering the simulation parts and then I'm going to hand over to Sabre jelassi who's going to cover the rendering and shading of the scene so diving into hini and you can see we've got a Geo node and in here we've got some geometry so the thing with you know small scale simulations is is that we're going to have to scale them up um you know you hear a lot of fix say always simulate at the real world scale but in the case of small scale simulations we do need to scale them up so in this case we're scaling up 7 um 75 so if we put down Tommy as a reference you can see this is real world scale and let's just transform Tommy down and we can clip his head something like that and then you know compared to that it's almost 10 times the size in fact let's just put down a transform and see how big this actually is we put a value of 10 here so not quite yeah about it is about 7.75 times the the the real world scale and that's the scale that we're using for this scene so we're just deleting the selection here we transforming this back and then we're clipping it and then you can see we got a hole underneath so we're going to put down a polyl and that's going to make sure that we've got a watertight mesh and from there we're going to prepare this for our simulation so uh we can just put down a null and this will be our our geometry collision and then we need to make a VDB version VDB from pons we can maybe increase this to five out Collision VDB cool so that's what we need for our collisions and then next we're going to put down a sphere and this is going to be to Source our points and what we're going to do is we're going to animate the scale of this sphere and we can do that using a fit in our uniform scale so we want an expression for fit and then we're going to say dollar FF so the frames and we're going to fit it between to I've got this expression here and what this is going to do this is going to scale our sphere so we're going to we're going to use the frames 2 and 15 so on frame two we're going to have a value of 0.95 and then on a value and then on frame 15 we're going to have a value of 0.02 so as you can see it scales down like that cool we're just going to position this above our head so so let's template our face and let's raise this let's make this radius one actually yeah something like that set this to polygon frequency of 20 and from there we can put down a flip source for now let's just increase this value and I don't want to look at this as a VDB I want to see the point version so I'm going to put down a primitive node and if we come under volumes we can say adjust visualization and then set this to Invisible and you'll notice we can't see our points so we actually need to come over here and we need to change this off to something and then change it back and now we can see we're getting um some of our points here let's take let's make our Point separation a lot smaller so now we got a lot of points click on oversampling typ 90 and let's take off this shell thickness so that should be a bit of representation of our sphere here with this thickness on is going to make things thicker we don't want that so just like that and now we have our points and in our final scene the we had actually a couple a few of these about five of these sources uh placed in in front of the face um but just in order to get you know we'll share the final project so you can take a look at that but to get something quickly I'm just going to put down a sphere something like this and let's you make it flat like this move it up above we can say VDB from polygons I'm just going to make a density version of this I'm going to make it a fog and then I'm going to scatter I'm just going to scatter Five Points something like that and then I can say copy to points it's let's maybe move this to the transform here so we can delete this later let's mark that and we can say randomize and we're just going to randomize the P scale and it's the value between and we can let's try something like that for now this a little bit in the head so can also transform it up yeah something like that next let's put down a Wrangle an attribute Wrangle and let's set some initial attributes um I think saber is using this attribute for some of the shading but it it's I'm so I'm going to include it here um but I it doesn't affect the simulation so I'm just going to include it for now and and if this is in fact used then Sable will cover this but what we do need is we need a temperature because we're going to use viscosity so let's um you know it's a float value so at temperature and we're going to say equal to one and we're going to set a rest for the position cool so from there let's put uh let's use an attribute vop and let's create a noise for our temperature so we can say turbulent noise let's fit that and let's put into color for now it give us a frequency of 20 so we can scale things down a bit cool make an amplitude of six two and let's expose this offset so this is going to be our break up in our temperature and we're going to want so we don't want to export it as color let's actually so let's put down a bind export and we can say temperature it's a float field and Export that let H our range so now if we take a look at our geometry spreadsheet and we come here and I'm just going to say delete channels and I'm going to set some animation on our offset here 0.2 and you can see that this noise is moving and that's coming from that offset animation pressing D on my keyboard I'm just going to change the background to dark and the next thing we're going to want to do is we want to give these points some velocity so if we take on point Trails you can see we don't have any velocity currently but if we put down another attribute vop and this one is for temperature so we can say call this Z temp and this one we can call setv cool and let's do the same thing pretty much we're going to put down uh an a turbulent noise take position put that into there and we're going to come to our offset promote parameter and Export this as V so now you can see we've got some velocities so let's increase the scale so we got some more variation 25 25 amplitude of four turb two and I think we need to make this a 3D noise Make This SP convolution that's better so now we have velocities traveling in all directions and like we did before let's give this an offset and that just means that this is going to change and that's about it for our source so we're just going to put down a null and we can call this out source and we can feed this into our flip simulation so so we have our source and we've got our collisions and if you're a power guy you might just be tempted to drop down a network and put down a a flip object a flip solver and a volume source and put together you little uh uh simulation but with flip you you know you run the risk of just crashing your scene so let's just save for now um save as save the file um but um and to avoid avoid uh making a mistake I'm just going to come over to this particle fluids and I'm going to click on this flip fluid object I'm going to click here click on my viewport and click enter and you can see it's built this little Network for us and I'm just going to copy this I'm going to delete these I'm going to dive back inside put down a doop Network dive inside and then let's paste let's paste that little setup quick cool um we want to link this particle separation so let's go copy parameter and let's paste it on our flip Source like that uh we want to make sure our container is not gigantic as you can see it's huge so let's go to volume Source here and then let's set this to 3X 3X 3 so now we have something a bit more reasonable and you can see we've just got those points so what we need is a volume Source plug this in here let's initialize this let's just click on collision first and then change this to flip source and we can take our Outsource past that there you can see Out Source cool and let's make the ACT Activation so we only want to emit from these points for the first 15 frames so we can just multiply this by this function I can say dollar frame so if the frames are less than 15 that way we will see we'll have a value of one and then after frame 15 it's going to multiply down to zero cool perfect save again cool so we can even make the smaller again although our Splash is going to Splash upwards that should be fine for now our gravity on our final scene was actually set to four and we were messing with the time scale so I'll show that in a minute cool and we're going to want to set up some collisions so let's put down a static object Fe this let's swap these round because we want the collisions to go in first and then the solver coming over to collisions and set this to volume volume sample uh let's set this by size and let's take a look okay copy that parameter let's take our sof path and this is our Collision that's our geom geom our Geo version and then we're going to need our VDB version this one cool so in theory we should have some collisions let's increase our resolution a bit let's go 0 five sorry 0.5 let's raise our Source cool and on our substeps let's let's use a fit so basically what we're going to do is we're going to use this to animate our substeps so we're going to fit from frame 10 to 15 so we're going to use the animation period is going to stop start from 10 to 15 and we're going to map the value before 10 to three and it frame 15 to one let's close that cap so as you can see now if we to this on it's going to be three until frame 10 and then it's going to come down to one by frame 15 and we can just copy this and we can do that for the max substeps paste that here but on this one we can increase this to five and to three and then we want to wait our um condition basically so it's going to use this decide whether it's going to use three or one substep or five and three um and so we're just waiting it more towards more substeps let's save again let CL V okay and in the final scene we actually also had an animation on our time scale was slightly modified so I'm just going to copy it from the previous scene um because it's basically it was this and then we multiplied it with another version so as you can see now you can see our time scale so now we have this slow motion effect cool so at this point I think we can afford to increase our particles it's try this for okay so I've just had a crash so let's be a little bit more careful and let's go up to our flip source and our particle separation needs to be two times the amount of our flip so so let's see what this is let's take a look at our points Times by two okay should be good that's not many points at all and I'll flip them I know that our final settings are that 0.5 but for now we're going to multiply it by 2.5 so that we are safe and perhaps we can even make this domain a bit smaller so let's come under volume limits and we can yeah let's make this all lot smaller for now make go smaller even [Music] again cool so this is working and it's playing back really quick and we need to tick on this so it plays back at the correct time and you can see our Sim is pretty stable with these settings in fact the entire simulation has been cached in Ram here but you know I think what we should do is we should actually just cash this out to disk okay so let's dive back outside here and let's put down a dop import fields and we're going to want this stop Network and we're going to want this flip object so let's copy this and let's paste that in there I mean and let's make this an absolute path so and on the preset let's take on flip fluids and we don't need the velocity we just need the geometry and the surface cool next what I want to do is create some visualization so let's just put down an attribute vop dive inside and let's compute the length of the velocity and plug that into plug that into the color and let's fit it and plug it into a ramp set this value to five maybe in and we can set this to W water cool let's make this a bit darker next up we're going to put down a null and we're going to call this two cache and the main reason I have this null here is um for my wedging setup I created uh a wedging setup that I will show at the end those tutorial and this this is uh you know we need a n called to Cache for that setup to work and let's put down a file cache I like to Mark these red so when I open up a file I can just navigate all the red nodes and cache them let's say explicit let's call this Splash Sim and let's change our frame range to 180 save once again okay so I've just come over to this button over here and I've run a flip book as you can see here and this is our result but how do we get from this to our final result like this and as you can see I've printed out all our settings on here and I think the best thing to do do when learning anything in Houdini and learning about the parameters and what the values do is to run wedges so I'm going to just quickly show you how to set that up and the first thing that we're going to need to do is we're going to need to install FFM Peg so if you just Google FFM Peg and you click on download FFM Peg you can come here and download for Windows and so coming over to these builds let's come down to here um version six essential builds so as you can see we're downloading this just wait for this to finish downloading so I've downloaded this ffmpeg Essentials build and you can see inside here we have a bunch of files and what I want to do is I want to install this on my computer and so I'm going to create a folder in my C drive called R way tools ffmpeg and then we can just drag and drop these files you can see I've already installed it but you just drag these here so you now have that and what we want to do is we want to um add a a path to this bin folder in our environment variables so in order to do that we need to come here and just type control panel we're going to go to system and security we're going to come here to system and we're going to scroll down to Advanced system settings and then here we've got environment variables and you can see here I've already created a path so you can just just do this by saying new and we're going to type in the path here so let's just take a look at how I've done that so you want to call it just path and um then link C drive riway um tools FFM Peg and then that bin folder and this is just going to allow us to write FFM Peg when we're executing some code and it's going to execute um that program so you know with that done we can come over to our Houdini launcher and let's go to launch command line tools and we just type ffmpeg and you can see we have our FFM Peg um installed cool okay now that we have FFM Peg installed we're going to add some information to our screen so we're just going to create a camera called camera one and um you can move around your camera by selecting this here and coming over to the camera button and moving like so um and then here we just bring down another geometry um node and if you dive inside we can ignore this for now but you can see we've got a font node and let's just do this again your font let actually for now let's just start from scratch so let's put down a [Music] Geo let's call this info come over to font and you can see this already is giving us our frame number and if we say dollar hip name we're also going to call our name of our file so let's give us some space here let's put down a color node let's make this yellow because that's going to be easiest to see and let's frame up and put this in place something like that and then we can come onto this info node and we can say keep position when parenting and then it's parent this to the our camera and now when we move our camera around that font is going to stick in place so we can come back back and reframe our Sim like that and then of course we can just add more info which is exactly like I've done here so let me just save this as a version let's go back cool so here I've just got more information and this is information um regarding our Sim as you can you can see um these are not quite linked properly and that's because we need to call that Geo flip Sim so let's come over to here and let's rename this flip Sim as you can see we now got some more information information and just this flip object is not showing up and the reason that's not showing up is that we need to like you know this is called dot Network 1 and this is called flip object one so if we come over to our IAL separation we just say copy parameter come back to our info and I like to make a separate uh font node here just so that I can say paste R of reference and you can see that here and let's come over to that info and let's see why that's not working so our particle separation is here so we need to replace this and see this was called flip object one so we can just take the this and we can fix this here cool so now it seems that we've got all the information that we're going to need to run simulations um we do add a micros solver later so that is going to be this um but for now let's not worry about it and let's jump to our out context I'm just going to enable this and what this is going to do is this is going to write our simulation to disk and as you can see we're reading in this to Cache so if we come over to our flip Sim let's just label this red diam side and you can see we've got this node to Cache so it's going to pull the information from this do import Fields it's going to apply our visualizer and it's not actually summing correctly because I've turned this cache off for now so you can see we're pulling that data in we're visualizing it and then we've got this n and then here we've got our cache and uh let's make note of where this is saving to um cuz we're going to copy this and we're going to make sure that we're paste that in there so that's reading that and then this out path is the same outpath as here so it's going to the same location so whether you cach from here or whether you cach from here it's going to be the same location and then what this does this just ensures that this caches and then um we move on to the next step which here is going to be running our flip box and in my case I have Aces installed so I'm navigating towards um you know I've installed ases in my documents so you can see um I go into documents I come into my uh open color IO and I go to Aces and I go to bait LS Houdini and then I select this srgb uh for Houdini um if you don't have ases installed you can just come over to none and or you can say Latin gamma and just make sure you have 2.2 here and just leave that blank that's close enough but I recommend you have Aces and you use this display lat that just means that your color information in your flip box is going to be you know as close to your viewport as POS possible again this batch is just going to make sure that this process finishes before moving on to the next step and then we're going to run our FFM Peg process so this code here is going to ensure that we um we going to run run run the Sim so um we're going to cach this out so here this is this is our flip book frames this is going here and we need the exact same path in our input here so we need to read that in and then save this out as our MP4 and I find I often get a lot of issues if I change these locations so just to be safe um I suggest saving your MP4 on the same folder as your frames just to avoid any um complications and I know this is confusing by just saying render current frame don't worry about that it's reading our frames in here here so if we come over to the very end here now and we just click on render you can see we're writing this to disk this is going to write our Sim I already had it cached but we're going to just write over this and then once that's done we're going to generate our preview as you can see that's happening here and we actually got a problem at the moment but don't worry about that for now and once this has generated it's going to generate our MP4 and you can see it's generated our MP4 here cool as you can see it hasn't cached our simulation correctly um so let's just take a look at why is that's happening and I think it's because this is caching twice so what I like to do is just come over here and turn caching off when I run our flip box so let's do that again let's come over let's delete this as you can see this is now working correctly cool so now we have our flip book okay so now that we have a a setup that can generate our flip books we're going to run a whole bunch so we can iterate over these values so this particle separation that is coming from here I'm actually just going to pin this so we can take a look we can see our particle separation is here our particle radius scale is here and our grid scale is here so for now um we want to run our simulations at a low resolution so this is our final resolution and I'm just multiplying that by 2.5 so that we could iterate quickly um also the grid scale um a final resolution was 1.75 um but like I said you know we want to run over this quickly so a value of two for our wedges and that's just going to be you know it's going to help it's going to prent crashes and we can iterate over our simulation and then at the very end we can increase these um until you know uh until we get a crash or we we're happy with our result so next up we just want to run through all our main settings and these are our main settings that are going to affect our simulation in this case um and you want if if you're not sure what something does you can just run a wge wedge so run a wedge with for instance since the time scale two uh 0.2 you can change that to 0.5 and and and see exactly what that value is is doing and and how it impacts our Sim um because we in our simulation it starts off very fast and then it goes into slow motion we we start off with um a high number of substeps let's turn our brain on and you can see the substeps come down after frame 15 as does our time scale and this just means that you know once we've got F once we have fast moving fluids or fast moving anything in Houdini you want to increase the substep so we can capture all that detail and then once it slow down slows down we don't need too much um too many of those substeps so if we take a look here we can see we're animating that here and we animating this with this this fit um I think I showed this earlier so this is basically just looking our frames and on frame 10 we're going to have a value of three and then on frame 15 we're going to have a value of one and this is for our minimum and this is for our maximum so obviously we want a lower value for our minimum and a higher for our maximum so we can see that that's going to be printed to our to our um flip book and we can do some comparisons and talking of comparisons I have a bunch here so uh let's take a look at this one last um so let's start with this one t amount so here we can see our vity is in fact on and we've got a value of 0.1 here we have a value of 0.2 here we have a value of 0.5 and here we have a value of one and if we can compare this in this case we don't really see uh a big difference but I would normally run these resolution uh these these these um these wedges and then once you get to the end come back and iterate over over it again you know it's a bit like tuning an instrument you you sort of start with your first string then you get to the last and then you go back to your first string and repeat the process and hopefully that second process you is just going to be um fine-tuning um and and you don't have to do too much work that second time around but for initial one we're just going to pick something um um so in this case I think we're just going to keep so in this case I think we're just going to keep a value of 0.1 which is our default here um next up we can take a look at the Splashy kernel vers swirly so if we come over to we Al we want to make sure that we're not receding we want the same am amount of particle so let's make sure that we turn that off we can take on verticity so in the verticity here we can see we have just a value of 0.1 and like I said this you know we we're not really see seeing this effect anything I think this is just this is just an attribute that we can use um you know can use this for shading or we could use this down the line but it's it's not really it's not affecting our simulation currently um next up is splashy kernel so let's take a look for that and you can see here we've got splashy or swirly and for the simulation we want a splash the velocity is smoothing we're going to leave that as a default of one but if you want to take a look at what how that affects our Sim we can see here here we have a value of 0.1 here we have a value of 0. 2 here we have a value of 0.5 and here we have a value of one so this is really smoothing out our shapes compared to a lower value like that so you can see exactly what that's doing but in this case we're going to you we're going to smooth out of shapes in many ways here so we're going to go with this default one here next up let's take a look at um viscosity and this is you know how they say blood is thicker than water and that's what they really mean is blood has a higher viscosity um value than water so you can see how with a high viscosity how thick this is almost like mud or slime whereas this this one is more like um a thin liquid so if we come over to our solver we enable viscosity enable there um attribute it's called viscosity and then you can just play with this value I'm not so sure what the final settings were we'll investigate that at the end but for now let's just leave it with a value of one and like I said you can increase or decrease this value um actually let's make it 0.1 for now and next we have this slipon collisions and if we take a look here with a high value you can see it's sort of slipping along the surface of our Collision wrapping around here and then dropping off um you know almost like raindrops curling around the Bonnet of a car curling underneath and then dropping off so this is obviously a very high value and we can just see how that affects our Sim and we're going to go with a value of 0.5 something like this this is a bit too strong and on these versions I'm not really seeing much of that behavior but you can see here how it's just wrapping around a bit and then dropping down so 0.5 is a good value so let's increase that let's save so far next up we have surface tension and um you know surface tension is kind of how you know if you place a leaf on the top of water and it sort of floats on top uh that's due to the the surface tension it's almost kind of like a an outer skin of on the water um just holding the fluid together so obviously this is a very high value surface tension of 10 this is a Surface value of .5 uh .1 and this is a mistake but but I believe this is um a very low value I believe this is actually almost close to zero um 0 025 sorry about that I don't know why this didn't update but it's clear that this is a much lower surface tension than 10 oh this is in fact off yeah that's what that is so this is no surface tension whatsoever and on our final one we actually had a very low um surface tension so let's go find that value it's over here enable this believe it or not it was 0.25 and um we're going to add another micro solver to control things and you'll see how that affects us some lator next up we have the stick on collisions you can see this is obviously way too high this looks like it's sticking on the on the boundaries even um so so let's try very low value of 0.01 [Music] um I think I need to run these wedges again CU we're not seeing the value um let me open the final file one thing I forgot to mention is we come over to behavior over here we're going to want to enable IDs and AG these are just attributes that we're going to use um later uh do ensure that receding is turned off receding basically means that it spawns more uh particles and we certainly don't want that we want to start off with a fixed amount of points and have those points run throughout our simulation and um because we're we're not receding and we have this ID attribute we can actually transfer UVS onto our particles based on the ID so like sort of Link the ID to a UV and we could have UVS on our flip Sim so make sure that you have those um enabled um nothing here there's verticity that is all correct and back to our volume motion this is all correct uh this viscosity scale is actually a value of one sorry about that um surface tension want to enable our surface tension and this is a value of 0 025 we can take a look at that here so we're just using a very small amount you can see here the surface tension is off surface tension of 10 a surface tension of 0.15 and 0.15 and and we actually just having even less than than any of this we're just having a tiny touch we want to um enable we want to enable the slipon collisions and under solver uh we're going to increase this to six so we can see what that does here you can see it this this should be this is a very high value I think of like 10 um I don't know why the info wasn't printed but this was way too high but you can now see exactly what it's doing and we just we going to have a value of six so something like this put the spal scale zero five I don't have a wedge for this but this is the settings in the final in the final uh simulation and I think this is a good place to save and let's just run a wedge to see where we're at okay so this is our result and we we're heading in in the in the right direction and we want to get this fluid to sort of pull and collect and and stick to the to the the surface a bit more and that's actually coming from an extra micros silver that we adding to our dop Network so we'll take a look at that next so I've just come over to my simulation and I have enabled cash here so I can just do this in the viewport uh let's have a look here and you'll see that there's kind of a link between this spectral scale and our surface tension so you know with the surface tension on and the spatu scale um of 0.5 you going see we're just going to get this very Blobby Behavior if we were to turn off the surface tension we no longer have that and if I enable this and I come over to the solver and I increase this to one you can see this also will solve that Blobby Behavior but we do want some of the Blobby behaviors let's try see what this does make it .1 2 and you can of course come and experiment with this but now final scene actually we did have a fin scene we did have a very low value of5 and our surface tension was very low something like that and the last thing we had was we put down a merge and I'm just going to copy it from our previous file this gas temperature update and we have an expression on here so this is going to multiply this down between frames 10 and 20 to 1.3 and then 0.8 so you can see here this is going to scale down and if we want to enable our information on our viewport can enable this let's just round off the our tank size so that we don't get this overlap let say two two three let's actually make this three as well for now and let's lower this cool let save and you can see we've got this cooling because we do have a temperature on our particles so we're going to be changing the temperature and the temperature to the viscosity so this is going to change our viscosity value um and let's take a look you can see we're getting the nice sheeting we're getting this nice tendrils and all we're going to really and all we really need to do now is increase our our particle count and you can see how this is like cooling you can see how this viscosity is now cooling down and we sticking to our face so this is basically our our final setup um the only thing that is different is you know where our points are being emitted from and I will share this file and the final scene in case I missed anything but you can see the effect here so let's just save this and for our final Sim let's increase our resolution and let's increase this to to 0.75 come back out here and let's save this to disk Okay cool so this is our final Sim that we did together and this was the original original file and you can see the only real difference is the position of our emission our source um so I'll I'll show both of these files and you can you can explore it and of course you know run your own wedges um investigate these settings I just think that's the best way exploring you know what a setting does really it's just by messing around and and taking a look so we going to we're going to jump into the final scene now we use this this project file and there's a few more things added like um UVS um putting some color on on our simulation and and the meshing so let's jump back into so we're in this final file here and as you can see the only thing that's really different is we've got these our emission points this is the original placing of them so that's slightly different to what we had but everything else is essentially the same or collisions and simulation takes place here gets cashed out here we just isolating the points you can see um we're we're we're selecting everything but the surface because what we get out of here is a Surface field and particles so we just want the points um from here we're just going to put down a group delete to clean up our groups and we're going to uh Delete all the attributes that we don't need so we're deleting everything except for these and from there we're going to put down a null and then this visualization is just like that visualization we created in um an attribute vop where we're Computing the length of the Velocity so if we take a look at this visualizer this visualizer does exactly that it's um Computing the length of the Velocity Computing the length and it's fitting it between Zer and five and then it's mapping it to this color so we did the exact same thing in the previous file with um with a attribute vop but this visualizer does it for us and from here what we're going to do is we're going to freeze frame our simulation on frame 60 and that's just because on frame 60 we can see our Splash is pretty big and what we want to do is we want to project UVS onto this and so we're going to use this UV project and we're projecting down onto onto our surface like this and in order to visualize that we can use this uh point vop and we can project the UVs to color so if we come to frame 60 you can see this is kind of how our UVS are being shot down onto um our points and because our points are not receiving our simulation isn't receiving uh each point has an ID and that and that you know that point number or that point ID isn't changing if we had recting on this when work because we would be receding points so you know but because we have a fixed amount of points we can map the ID to the UVS and then we can just copy um we can copy those UVS onto our points so that's what we've got here so um yeah Freeze Frame project the UVS U copy those UVS onto our points here we just visualizing that here we have a uh we're not actually using this um there some stuff here for creating a Shader M but we're not using it but essentially we're coming back here um and where yeah well here we here we're creating some color so you can I think this is what we ended up using we didn't end up using the UV part but I will explain that here we uh this is what we used we just used some color variation so if we dive in here this is not being used and I believe we actually just using one of these we're not using all of them but we importing the rest we've got a constant value and we're adding that and we're creating a turbulent noise and we fitting that and then we're exporting that as mask and here you can see it as color so we're creating this mask mask one let's let's see which one we've actually using here well I'm I'm going to show all of them so you can see we've just got some variation and of course we can change the frequency of our noise it's copy parameter you get the idea we can just get some variation on our on our simulation I think this was 2 something and here we have this to create our mesh so this particle surface fluid node is just going to create our mesh for us it's may take some time so you can see our mesh and let's investigate our settings a particle separation is you know that original simulation that we use so this is the the same particle separation and ASL Sim voxal scale um we are roing it a bit and we're transferring some attributes but this pretty yeah pretty standard meshing stuff and we're transferring that color on those different Mass those different color attributes back onto this mesh so now you can see we've got that color on our mesh and here we're transferring the UVS and I'll I've cached this out so I can show the UVS a little bit better down here here we just REM we just um multiplying our velocity down that's just for the motion blur and this just because you know it's a slow motion effect so we need to um you know if we're if our time scale is 02 we need to multiply our velocity down by 0 2 so here is our mesh I've just cached this out to disk and here I just wanted to show the UVS cuz it's it's a bit difficult to see that color so I'm just deleting that color briefly and as you can see we've now got these cool UVS on our on our mesh um here we can put an image on let's put this after our color delete yeah you can map any texture you want to this and it's going to be stable so if I run a flip book let's just do that now you'll see that we've got stable UV so I'm just going to let this run for a bit so as you can see we now have these UVS and they are mapped to our liquid simulation and you can see at frame 60 I think it was our UVS are pretty much spot on and then they they sort of um liquefy before and after so they shrink before 60 and they expand after 60 and of course we can then you know apply a texture to this so that's it for the simulation and meshing part thanks for watching see you

Channel: Rebelway

Views: 13,341

Keywords: Houdini Tutorial, Houdini, SideFX Houdini, Nuke, Nuke Tutorial, VFX, FX, VFX Industry, Special Effects, Visual Effects, Hollywood, Simulation, VFX Tutorial, VFX Tutorials, fluid

Id: Tfea1t8I344

Length: 71min 46sec (4306 seconds)

Published: Wed Feb 07 2024