Houdini Ground Fracture RBD Tutorial

uh welcome to this tutorial i'm going to be showing you an approach of setting up a ground fracturing shot like so um hopefully by the end you'll have a basic skill set of just how to set the different stages of it up um and then you can obviously expand and develop to suit a shot that works for you um so yeah hope it's clear and we'll hop into it uh so to begin with we're gonna look at inspiration because it's good to have an idea of what you wanted to look like uh i found this thing on instagram by jtfec of a shot and i thought it looked pretty epic so we're going to roll with that as a goal um as you can see it's a ground fracture it looks from a glance obviously this is causing it but um actually you break it down a bit by frame i'll try and pause on a clearer shot uh you can see that the the staff itself isn't really interacting with the floor so this collision is more than likely caused by an object underneath the ground here and that's just sort of whacked in on top so we're going to approach the shot like that as if we were trying to do it um if we break it down a bit more we have the initial fracture here on the floor you've got obviously the pyro and then you've got these little sort of shards coming up and depending on how badly the sim time is uh these like shards will either be in the fracture itself or just a separate particle simulation source from the fracture um we'll see how timing wise goes uh so yeah this is the inspiration uh we'll try and get something to look like this uh yeah we're gonna jump right into it so hopping in houdini i'm gonna go with the geometry node i'm gonna call this fracture might as well be organized and then whack in a cube or a box um i'm going to quickly show you a few different ways of sorting fracture points and then you can sort of depend on the context of the shot you're doing pick which one you think is easier but a good place to start obviously is always with the scatter so source points um so as you can see it's sourcing points on the outside only uh there's no internal points here i know it's quite i'll try and move it so you can't see it there um so a good thing to do is whack an iso offset and just before this this then sources points inside of the cube which is great because then gives us a bit more control of the fracture pieces itself another good thing to do with scatter is to untick relaxed iterations this basically means it's less uniform randomizes it it gives us much natural more looking uh fracture pieces as well and i'm just going to lower the force account to about 100 so it's nice and quick to show you so we connect this with the voronoi fracture node and then the scat points in the second input and here we have our fracture you can enable the visualizer here with a little toggle and you can see the pretty colors and i'm just going to disable that for now and then i can explode a view on there so we can see the pieces so from a box standard way of approaching it this is a good start um the iso offset you know sort of just gives you a good looking thing very quick and easy so there are a few of the many many ways i'm going to go through next one is going to be an l system and help if i could spell it so another system in houdini um i just toggle the display creates like a branching tree type thing and then if i just move that you can see the generations this can be animated i think it's somewhere yeah it's here in the shelf tool as well if you wanted to do that um basically we're going to take this sort of tree shape and then use that to source the points so i'm going to start with just this kind of two leveled thing i'm going to attach this to a transform and we're going to rotate it 90 degrees so it's flat and then also scale it down uh i don't think we've got the right one there we go to zero on the the z-axis so it's flat it's like a tree um let me just i'm actually going to make a new box for this just keep it nice and separate so if we show that grab the box and also make this a bit smaller just for the sake of visualization all right so now we've got our l system and our geometry here what we're going to do is we're going to resample this l system here to give it some more points so you can see if not it would just have less but i'm going to whack the the length down which is sometimes confusing because down usually means increase the resolution uh but that's that and then we're going to also put a point oh sorry a scatter on this and then a point here if i could spell it so obviously that scale is way too big so i'm gonna bring it down uh something like this i'm actually gonna take this transform and stretch it out a bit just to spread it and then we can also increase this a bit just to give it a bit more noise so then we can now go in the voronoi fracture similar to how this is set up we grab the input geometry we grab the source points and then here you go you can see uh i think that's fairly you can see the tree shape basically so i'll see here are our points and then there's our fractures accordingly uh it will depend on how many scatter points you have how clear it will be um but yeah that's just another way of approaching it uh i want to quickly show you another way i want to be rapid with this one so we have a box i'm going to do a paint node or attribute paint sorry like this and we're going to paint on if i know it would help if it increases divisions a bit uh that'll do it paint on here and then we take the scatter again but this time under the density attribute we check that and we change it to mask so now it's only sourcing points where we just painted on the older versions of houdini the paint node would just use the cd attribute but uh 18.5 by default or 18 sorry uses just the mask so sort of keeps it separate and then i'll see again with the voronoi fracture hook that in and then you can see disable points sort of tailor it so you can obviously paint sort of where you want it to be more fractured uh the cd attribute in general is actually really powerful uh if i just attribute from that i can show you another way which you can tailor even more uh for the sake of this i'm gonna actually up there are um divisions because an attribute map it would help if you can sort of see the image uh so i've got this alpha mat i drew onto workshop black and white i'm gonna whack that in so it's like that and basically using this same approach just with the the cd attribute by default now we can determine the density of the points so it's also on the bottom because i'm being quick so i didn't apply it to the just one side but visually there you go those are points and then if we attach this to the voronoi fracture you're now sourcing points based off an alpha map so this is useful if you're doing something where you need specific points based off like textures or areas that you just you don't want to paint um yeah this there are just a few other ways uh we're actually going to do another way for this tutorial so i'm just going to actually delete all of that we don't need it so to begin we're going to wipe down a cube this is going to be our ground i'm going to lower the height to about 0.1 uh just sort of change uh i just got a nice shape so we change the dimensions and the size this is going to be our main fracture geometry and to source the points we're going to use a similar method to the l system instead we're going to use a curve um we're going to hop into the top viewport make sure our curve node is selected click this sort of three axis icon and then we could start to plot the points that we want to go to be hit enter when you're done we just display this you can see it's very polygonal so i'm going to change from polygon to nurbs that'll make it a nice smooth curve and as you can see here there is not many points so a re-sample node will resample it add more points which is what we want i'm going to attach a scatter node um we can disable relaxed iterations uh also whilst i'm at i'm going to lower it to about 500 so it's a bit quicker and then attach a point jitter node lower that scale and we can sort of see the points have been uh generated so obviously you can exaggerate that curve however you want and then it will change b of houdini is it's pretty much all procedural um so just to visualize this is our voronoi fracture setup at the moment i'm just going to disable points so we can see a bit better we can change the number of points and then sort of determine how it wants to be also a good way of doing it is if you display this as a template hop back to the curve you can actually edit these points and it will do it so you can still see what you're actually doing um but for now we're gonna stick with this in fact i'm actually gonna increase the scale of the point jitter because it's looking a bit narrow and sort of streamlined here so if we just expand this a bit we get to see a wider area of dense fracturing which is cool that's what we want um and again you can always come back and change it if you you don't like where it's going so several fractures great it it's quick it makes inside and outside groups uh so you can sort of texture the the perimeters of the inside and outside as it sort of suggests there's an rbd material fracture node uh that one it's slower but i think it actually gives better results so uh i'm gonna roll with the voronoi for now and and then at the end i might just whack this instead and see so compare the two um but yeah it's slower but it gives you a bunch of customizability for like the internal noise of the fracture points and detailed and whatever so we'll probably come back to that uh pop it in but for the sake of efficiency we're going to stick with rna so for our null we're just going to put frac out we'll find out crack geo um a cool trick as well if you hit c on the keyboard it'll bring up the color pad out you can also click it there uh just to help visualize stuff a bit by you could change it and if you want to change it for everything in the scene you click control click so i want it to be red then whenever i pull another null it'll be red as well so there's a cool quick little thing that might help you out so now we're going to set this as an actual uh glued object so i'm going to start with a dot network hop inside this essentially makes this one active so when we back out to the object level we select this geometry and we get to rbd glued objects this will then make it inside that dot network we want so using the shove tool yeah it does a big favor it generates all the days we need and then we can go from there it's quick um so yeah you can obviously set up individually with your own nodes but um the sake of time is probably not worth it so next uh i'm going to show you obviously the glue we're not going to fracture it just yet because if i click play nothing happens so just to make sure it's actually identified as an rbd object when i hop a gravity in there it should start to fall there we go so we'll bypass that for now because we don't need it we're going to actually set up the sort of collision geometry first of all because i'll see if these are shooting out we don't want them to just fall so i'm gonna do is i'm gonna hold alt and drag on this box so we have a duplicate and this time we're gonna expand the width to something like four uh and we'll leave we'll actually sleep [Music] the z-axis as is i'm gonna boolean subtract i'm gonna take this first input and the second input from the original box and now we have this now obviously if you actually simulated this then they don't fall through the floor so we're going to hop back to this box and drag this red arrow and just sort of expand it down a little bit so now we've got a nice solid ground area again i'm going to put a null just so i'm going to put ground geo and then hop into the dot network to make sure we're sourcing to this go back to object level collisions and static object this will then set up all the attributes and uh static object inside the dot network just to double check see there you go collision source has been generated and then in the dot network you've got the static all right i'm going to click l this just sort of layouts the the node so it's not cluttered so for the actual fracture we're going to start on that now obviously we have the the geometry um we're gonna actually build a piece of geometry that will animate going through this and that will source it and then go from there so i'm going to leave this on the the voronoi template so we can see this get an idea and we're going to place a cube i'm essentially going to model a sort of wedge type shape and i just have to be this big uh it's actually quite useful having this template so we can see how wide it will be and how much it'll affect it um make it by the height so this is essentially going to just plow through it like a snow plow um i'm going to display this we can actually see it make sure we're on the edge selection method go to the cursor i'm going to start by beveling these two edges the poly bevel this will just give it a nice smooth appearance and then grab these front three and then i'll give that to it transform lower them down so we just get a nice sort of wedge shape which is nice um we can always come back and change it if it's not quite giving us the idea we want uh but the main reason i beveled the side is just so it's a bit more smooth otherwise it'll be quite chunky uh when it's interacting with it so here's our transform and we're going to attach this to a null again just because it's a good habit to get into i'm going to call this one uh collider because this is going to be the piece of geometry that sources all of our uh at fracturing so i'm just gonna move the dot network to the side just so it's not getting all cluttered here make sure this is displayed up in the dot node in fact now sorry i apologize we're actually going to transform this here i want to move it back i'm going to animate it and now let's write it so if we look back at the inspiration here timing wise it's pretty quick uh i'm not gonna count how many frames it is uh but we're gonna try and just sort of simulate a similar sort of speed uh so we'll start we'll start something stupid like frame sticks that'll be our start the keyframe just a little bit before anything happens and then over the course of we'll try about one and three quarter seconds i'm gonna have this wedge over here so i'm setting keyframes by clicking alt and clicking so now this guy is moving here and that's a pretty similar speed to the video obviously the the length of our fracture it probably isn't quite as long as inspiration so we'll finish quite quick but that's okay and just to sort of make this animation a bit more linear we're gonna shift click uh the translate bit and this will bring up the animation editor i'm going to click space and f to see it all control a to select all and then select the straight line this basically means that the keyframes are interpreted straight there's no like fade in slow fade out slow it's just linear um so yeah i think i'm going to start with this sort of speed and then now we can take this null up in our dopp network jump back up to object level hit surface collider and in theory this will work i'm praying it works if not i'll be worried so if we click play it will take a minute collision is working uh now it doesn't take a genius to see that that isn't what we're aiming for uh this is to do with the glue strength um so here in the glue constraint node within the dot the strength is ten thousand now that is way too high for what you want um when i load it's about ten see what that looks like so it's starting to work how we want it obviously again the actual fracture sort of thing now you'll notice as well that this whole object is crossing as an rbd object uh obviously it's fractured so it's separating here but as soon as this bit moves this it will affect the rest now we don't want it to do that we want it to stay still and we only want this sort of inner section to be fractured so there's a few ways you can do this um for the sake of easiness i'm just going to use a simple uh attribute wrangle and bounding box to just identify certain pieces of the fracture as inactive so to start with we're going to whack our angle in if i could spell it attribute wrangle i'm going to place this just before the dot import node that our included object created earlier on we're going to change it to points if it's not already i'm going to write the expression i at active equals one i apologize for that noise uh i have it has a hotkey on another piece of software so i'll make that little ding ding um so i active equals one that's basically saying that all of this is active at this point um which it already was just to reference it so then i'm gonna go group create i'm gonna whack that in there straight after we're going to disable base group and enable keeping bounding regions and this will create a box you can have it as a sphere an object if you want it as an object you can input that as a second one here and also take that shape but again for the sake of this tutorial i'm just gonna keep it as a box i'm gonna increase uh decrease the x value increase the z so it goes all the way across and finally i'm gonna move it so that it's only grabbing the outside ones i'm just going to display this so it gives us a bit more of an idea what we're actually doing here so as you can see it's taking a lot there because our pieces are quite long and narrow there's no like sort of things breaking them apart so if we move it further this way it's not going to grab it so there's a few methods you can do to fix it as always with houdini and we can adjust here the point scale uh the scale of the point jitter and that'll obviously change how wide you want it to be because i want a simulation to be quite straight down the line i don't really want to adjust that you can change the curve itself um however i'm going to grab another scatter lower the point count to around 10 and then attach it to our original box geometry so now if i just hide that you'll see there's a few points being sourced and i'm actually going to merge this with the point jitter so there now become the curve and you've got the separate ones so input this is our points and as you can see it'll create sort of these long slab bits uh on the edge which is what we want because we don't want as cool as it would look these long like shard bits we need to break it up so how this is here we've got the shards and then sort of backbone that we can just select using the um the wrangle so we can sort of just increase this a little bit um something like this the way it covers all of it and now we hop back down to this group node display that flag and we can sort bring this down now we don't have to go really deep in we just need to make sure that all of the edge is uh selected which is what we've got so that's that's a way of fixing that solution so we're going to rename this group to inactive uh and then also we're going to make another group that i just copy i'll click it it'll be quicker press y to cut that and drop in after and then this time just position it on the other side so and we'll put in active two uh i also forgot to change the group type we need to have that as points um you can do it as perimeters if you want um but it's up to you i think points just is a better way of going about it and just reposition this because i've changed it slightly points just gives us a bit more control because it's more sort of detailed uh next we're gonna put an attribute wrangle after this group we're gonna select the inactive in an active two groups that we just created uh i'm gonna go i at active core zero again i apologize for that sound uh hopefully it's not annoying stop import redisplay that so now what is going to happen is it's going in theory these outside pieces aren't gonna move at all and then this whole fracture sim won't be affected and shut off like it's starting to do so if i just click play that's exactly what we want to have so we're getting that sort of look the inspiration was getting in terms of it being sourced up here which is great now the elephant in the room is that these things are shooting off like mad so that's because if we go back into the top network there's no gravity and we need gravity so we're going to enable that back again this will bring it down a bit more realistic um like so and now we can start to sort of tailor it to what we want so the speed wise i think it's okay we can always change it again uh but for now i'm gonna settle if we hop into the rb packed object node we can go to physical and we can adjust here the bounce the friction stiffness and the density um you can hover over them and it will give you a brief idea of what it does but bounce is essentially when it comes into contact how much sort of bounce it has so if i whack that i'll do something ridiculous like two it should sort of shoot off and we don't want that so i think we'll increase it slightly from what it was it was 0.5 0.7 should just give it a bit more uh bounce which is what we want there we go and in the inspiration there is a character here so at the end i might grab a mixed mode dude just have him here so we don't want this sort to scale higher than he would be uh we want it quite grounded um but i think we're getting that sort of look already we're trying to let this sim out a little bit oh it's always good to have an idea what it's all looking like so back in a second right so this is a current situation obviously he's gonna have to ignore this wedge because that won't be shown in the actual import i don't think um let me just hide that so this is where we're at i'm i like how we've done the fracture again there uh there's still a few obvious things that are wrong um if we wanted to actually go about how you were doing an actual scene this boolean here wouldn't just cut off uh but for the sake of this i'm just gonna sort of cap it here or set up a camera control clicking that way it's if we go back to the top import it's only on our screen we won't see the rest which is fine like that so general movement i'd say we're sorted there's a few things we can change still as you can see they sort of roll about here uh even when they've landed so we can adjust in the dot network the friction uh if we whack it we double it see what that does it's already having that much of effect so go to the static object increase that a bit uh lower this so i'm looking at this as my sort of reference slows down a lot more um actual bounce of the fracture could probably be increased again uh we can increase this bounce as well doesn't really matter um but i think i think i'm gonna settle with that for now and that's the basic premise of that so as i was sort of mentioning briefly at the start you can the voronoi fracture compared to the rbd material fracture there's a few pros and cons in terms of interior detail of like these these pieces here um i'm just gonna explode review this just that way we're not simulating our disable sim so they're very flat the faces of the interior bits and we don't necessarily want that because it won't look great it'll look just very polygonal oh no that's not good so there's a few ways we can do this we can switch to an rvd material fracture node like this again a con with this is it takes a little longer to cook and we can sort of look at these and there is also an rbt interior rbd interior detail node sorry um which basically has the same options as this however we can just hook it in after this uh furnace fracture if view which is what we want uh let's take a piece that we just want to look at look at this dude he's quite big so we can obviously with the detail we can lower increase it the lower is the the higher resolution it would be but again it at the cost of simulation speed so which point one it for now you can see it's starting to make more divisions um noise amplitude it's just the scale of the noise increase that uh so it didn't do much but if i just drag it you can see uh it's off here up if i grab the right one okay so just how do you want it i'm just gonna put that back to default for now because i need it uh you can also change the frequency of the noise so if you want it more often which i think we do just because it makes a bit more we're scaly yeah you can enable fractal uh type different sort settings warping but for now i'm not going to touch any of that uh we're actually going to lower the detail size even more we're going to 0.01 that's much clearer so comparing it if we just bypass this there's a massive difference um but again simulation speed so you're gonna have to adjust it how you what you're comfortable with i'm pretty comfortable with waiting so i'm gonna actually keep it enabled um so we're just going to get realistic looking fractures here it's like concrete ground being broken up and that's working well uh so instead of having this just go to the exploder view we're going to now attach this to the the actual fracture system so now when we go to dop import it should take into consideration those interior details it will take longer to cook so i'll be back when that's sort of cash down uh right so it's sort of cashed out uh also just make sure you re-enable simulation she did disable earlier uh uh took me a minute to actually work out why it wasn't working um so interior details all set up and then plugged into the the the tree was going for so dopp import and this is where we're at so as you can see if i go to wireframe mode you can see that there's much more detail on the inside nodes uh pieces uh yeah it's working actually looks really cool in wi-fi mode as well almost like a tune shader um now it's just really a case in terms of the fracturing just sort of tailoring the dop settings to something we're happy with um just in the bounce and so on uh just to give us an idea of what it will look like i'm gonna make a merging attach that to the ground geometry combine the two that way we just see the floor as well and then obviously it'll bounce off it as well i don't think i'm going to stick with this camera review just because it's not great but for the sake of your boys it does the job um so yeah so i've quickly flip-flopped it uh i'm gonna stick with these sounds um otherwise i'll be here all day just messing around with them i lowered the bounce on the rbd packaging back just because of the stars getting some really shoot up um so this is where we're at um again i might at some point extend this ground floor out just so it's not falling off the edge um but this is just sort of a tutorial on how to do it as opposed to get a cool looking shot um so yeah i'm pretty happy with it i like how these sort of edges rise as it goes through uh the next step now is to source some of the pyro to get some of that dust kick up so to do the debris we're going to uh well i've already set up a nil here with the fracturing at which is cool and we're actually going to just create this debris sim in the object level just because as an importer that it generates anyway so with that fracture outload selected on the display we're gonna go back to the rigid bodies tab i'm gonna click debris so this basically creates all the nodes we want and then sim network source and then the output which is here it's play you'll see we've got loads of deputy uh also is worth noting i did bypass this interior detail uh just temporarily because otherwise it's gonna take a lot longer um but at the end i'm just gonna re-enable that and pretty similar um so yeah we've got the basic geometry and now debris is being created now if we hop into this sim network here you'll see we're sourcing from points if we source from all points here we'll just create a lot more we don't need that after all this debris is going to be turned into smoke so the point replicate does what it says it understand the tin it replicates the points um probably don't need it so i'm just going to bypass it uh again noise we enable it later on if need be uh life expected c in one second i really want them to hang around that long so they're falling down similar to how the rbd did at the start and they're also although it's extremely hard to tell they're not colliding with the fracture they're just being sourced from it and so just to give a bit more of an accurate uh sort of result we're going to add some solutions to this we need a static solver we need a static object and we need a couple of merchants to them so first of all we're going to attach the solders together what's the whack the output node in we can already create one but we don't need that and then up here merge and then duplicate the static so we have two static objects one's going to be for that ground geometry that we made and the other one is going to be for the fracture so we'll start off with the ground over here to the soft path hide that when we go back to this fracture and we made a null called ground geo except that then we just hide the display and then just go to put it there to see the guide geometry uh we don't really want it to be like this so we're going to change the convex hole to a concave this basically means it will just form the shape it won't try and cut any corners and it'll just give us a bit more accurate uh result and if there's a static object i'm just going to hide the guide and redisplay the second one is going to be the fracture so we're going to the soft path and this is going to be the frac out node that just created uh again if we just show the color the guide you'll see that it's not grey and if we start to play it it doesn't change the the guide is sat as it's still the original cue so what we need to do is we need to enable deforming geometry we'll make an active one as well um so now it will move with the guide but again that is not what we want as cool as that does look uh we need to change the bullet day geometry geometry representation to concave again you can do it sort of like reducing the divisions or whatever but okay it's just a solid way of just getting it straight away it might take slower it depends on your geometry you'll have to sort of go with it however so now you're seeing that this is our guide geometry uh and it's it's the fact so if we just enable points a lot of these blue ones should remain up here they shouldn't be falling through obviously they will at the sides because there's nothing stopping it and it should last around a second which is exactly what's happening um now it's a case of lowering the lifespan of these points uh it depends on the ground so you you trying to create because obviously if you're doing this in like a rocky desert it's probably going to be quite a lot of dust whereas if you're doing it on something that's not stone it probably won't be much um as as is we have a concrete uh fracture we want the the dust to be there a decent amount of time you can always adjust it in the smoke sim so i think if we disable the points uh it's a pretty good position where we just hop back up here see this is debris and if we just watch it in beauty we've got the collision we've got the sourcing and they last for about a second before they die so just before we start the smoke i'm actually going to save ourselves some sim time uh when i go to this import node i want to bin it i'm going to sort it for a dot io just because i prefer it uh select the debri doc network and then the dot node is going to be where is it the output so now we should be getting nothing uh because we need to add a field import so here again everything we don't want everything um we don't need to change that and we need the object now the object is a pop object one because we only want the particles here which is what we're getting we don't need the geometry because we'll have that as a separate thing it's also quite a nice way of visualizing it so there's our top import done uh i'm going to make a right now we'll keep in this one we'll actually change this to uh we'll do the smoke in here so here's our points and we're going to delete the ones that we don't need uh so if i just hire show the fracture again but with the merge and loader can just sort of see it um again so if we go back into this debris we don't need the particles that are falling down to be smooth there's there's no point it'll just slow us down so we're going to do a similar method to what we did earlier with the groups i'm going to change it to points because we're working with articles as you can see they're all selected we don't want that so i'm going to base group it get lost uh keep in bounding regions enable so now we have a box i'm gonna make that box the same size as this which i think it was four by four yeah yeah it looks about right and height wise we'll lift up we don't want to cap the top but we do want to cap up on there's no point uh having it underneath if it's not going to be shot so by now it's only selecting the ones inside um i'm going to delete this and select the uh fact now we'll name the group delete parts and go to delete then select that group now get rid of everything inside that box we don't want that so we're going to change it to delete non-selected so it's the opposite direction so now we just have the points uh inside this sort of thing and they we do have the ones that sort of seeping off there but that's actually okay because they they don't carry on they die um which is what you want so now in terms of setting up the the pirate's sim we're gonna usually do and no i'm gonna say this is uh debris out and there's a few ways we can do we could do this with a vdb from particles against a volume or we can just straight up hit the the pyro effects draft tool um we'll do that first we'll see if it works um let's start another not a dopp network in here make that active select that into power effects um a good one to start with is always below your smoke uh wispy smoke is good and so it's dry ice but i'm gonna go with billowy so now we're here and let's see what happens so straight away again smoke which is a good sign if i just play all as one we're seeing that that smoke is lovely um a few things we do need to do though so one bounding box as you can see is is it's flat out hitting we don't want that um so if we hop back into this top network here and go to the gas resize container we can disable clamp uh this will slow it down um we'll see how quick it does it that's not too bad so as you can see now it's not hitting these borders so it's got plenty of room we can clamp it still and just increase the padding um depending on how long it'll take uh sort of sim as we're working through i might enable that but for now we'll keep it here so straight away uh the actual sourcing looks great we're getting what we want uh it's very dense and sort of lasting a long time now for the sake of pyro i'm going to click d on the keyboard and over the viewport and change the background color to dark just so it's a bit easier to see um and also if we go to this smoke object we can uh enable the density it just gives us an idea of what we want and we can change it here um whatever the default though one now an important note is this division size uh it basically determines the resolution of uh sim so we're gonna leave it at default just want to work it through it but uh when we're ready to cash out we're gonna lower this quite a bit just so it's i was in high res and detailed um just be careful if you like too long uh too much it would just make the sim time a bit bit crazy and slow you down so just keep that in mind and obviously this sort of visualizing is just a viewport opengl sort of system uh we'll actually determine the destiny density uh in the shader when we come to render but for now we'll keep it at that so we go back to the inspiration we'll see we'll look at their pyro and we'll sort of see what was a good fit because this is a great example it's quite subtle it's not very dense uh especially on the rendered version and because the main aspect is the the magic section um as you can see it doesn't rise much it doesn't really weep like uh dry ice sort of just jiggles it actually looks quite turbulent if you it's hard to sort of see but um i think we can actually turn this down quite well inside the the pyro solver so first things first is dissipation uh we don't want it to linger around a lot um if i just sort so see where it is so we probably want a second um for it to stay alive so dissipation we're just gonna up it and again hovering over it will give you an idea i think one's to be a bit high but we can always change it i know it's actually not that bad she probably lowers still um don't want it to sort of rise up like this so that is buoyancy i'm going to change the point to lift to zero and we'll just direct zero and let's see what that looks like the thing about pyro's is basically just tweak settings until you start to get a shape you like um with that again it's like the complicated micro solver stuff um so i'm not qualified to talk about that yet um so yeah i'm actually gonna go back out so you still see the whole thing so now it's looking a bit too subtle not very dense um so because we're altering it [Music] to this thing we're gonna actually up the resolution a bit just to get an idea of what it started to look like um let's have a visualize density on one white up to two as well and we're just going to look at this now so i think we're not far off is it's still very subtle as you can see um but here it is equally as sort of um so in terms of sort of expanding wise i might enable the buoyancy slightly like ever so slightly um just to give it that um variation um when we go back to the shape here the this is quite turban uh the reference so well maybe put that up a little bit to five i'm gonna enable the shredding i'll give her some nice sort of like almost sharp type of flake flakiness to the the smoke and uh yeah we'll see how that looks like first so as you can see already you have to open that resolution it's taking a bit longer each frame um it's still a bit billowy which we don't really want i know i did click the billowy shelf um but what it seems when you actually play with the thing it's sort of working out now we're going to do what we did with the the particles we're going to make it collide with the floor and fracture pieces otherwise it'll just look weird as it's falling through uh to do this we're going to do in here we'll do some object mergers because we're going to swap it to vdb stuff now because uh it's been volume collision so if we go to the main fracture we need the ground geo into this object so if we take this grangio merge and we go with a vdb from polygons i'm going to lower this resolution to about 0.1 just to conform to the shape a bit more hop into the top make it active pop back select this and object again this will just make all the necessary nodes we need um same with some time so in this static object node it won't work unless we change a few things so i'm going to make an active object and uh yeah we will enable to form it i'm not entirely sure if that does anything uh but just to be safe i will uh collision detection we're going volume collisions and then here's division size so if i display the guide only you'll sort of see that it's angled here like a bevel uh we don't want that so i'm going to load the device something like 0.1 and as you can see it will sort of conforms the actual shape we need which is great now if i just click play smoke will collide with the floor so here you can see uh if i just hopped back to the object level um it's working uh the sort of collider geometry isn't as high as it could be so so it's not working perfectly but uh as you can see this sort of like there's no smoke here there is these old seeps but um i think that's from the particles spawnings or like either under the geometry in the previous step or just falling through but again we can just get rid of that when we're rendering with a bounding box or something uh i'm going to stick with this um these little bits not really a concern um obviously i probably should have not had it as a drop off on each side that way they wouldn't fall but it's not going to be in shot so we should be okay so if i hop back into this geometry node the debris go to the dot network we'll see that that's pretty good and then i enable a fracture just so we can see it see that this smokes one of it actually just kind of run a quick flip book of this just to see what it looks like in real time so here's the flip book um it's looking all right in terms of the areas of sourcing but straight away at the start there's almost like a delay in the the smoke being sourced within around around 20 so um we're going to fix that in a second um as well maybe it's just a little high on these sort of um whispy bits at the end um but nothing to worry about so if we just close that uh hop back into this sim right so to fix this um sourcing error uh if i just play it now see there's nothing until like frame 16 and then the smoke just appears and so we're going to do is we're going to actually go back to what we didn't do the start i'm going to actually clamp it um if we did it now it would still very blocky but the starting is smoother it's not like a stop start it's or gradual um so if we have the bands to something big like 15 we're getting close to where we are um but as well that's great except this is where the sort of bounding volume ends so if i stop it there you'll see it's just a flat line so that's not a problem we can just go back to the smoke source here and sort of extend this out a little bit it's not going to go any further down so that's not a problem so now what happened is it can it has that ability to sort of it does look a little flat but i think that's just the particle sourcing uh like the shape of the particle and it goes up i just yeah this all goes straight up here um so i'm not worried about that that looks okay i just pop back into the top i'm going to make this uh bounding box just further out what are the whole thing doesn't have to be perfect in terms of coverage and then just in case it starts never play it i do you can see okay it's starting off a bit more smoothly it's less power point and more a video um so yeah if i just show you with everything this is where we're up to i think it's turning out pretty well so far uh actually gonna run another flip book because flip books are cool and they're useful for finding out so i'll be back after that so this is the flipbook uh the rbd bit looks good i think when i do the the main um sort of cache i'm going to re-enable the interior detail node to get there the internal noise on the on the bits uh the smoke i like the sourcing is pretty smooth i think i might edit some of the the parameters in the dock just to tone down the shape a bit more uh maybe change the density um i'll see if i do i'll still i'll let you know and then finally when it's ready i will lower the resolution oh increase the resolution by lowering the the division size and then see what that looks like yeah so uh this is what i'm gonna start with um basically didn't do much in terms of uh oh and i just sort of turned these uh parameters in um yeah it's about it i added some points to lift going down just to sort of give it a bit of a like uh most dry ice kind of effect here and then oops the shredding to give these lots like kind of whistles of smoke inside it um that's basically it for the this simulation tutorial um what i'll do now is cache each step um with the the final output so i'm going to re-enable this interior detail load here cache that and then cache the debris and then finally up the rest of the pyro and then hopefully get a cool looking render out of it just quickly uh to cache and just drop a file cache node down at the end of each bit and then i'm gonna select our frame range i'm going into 72 because this sort of camera thing is so it's only a small chunk so there's not really much point cashing out any further and set your firepath and click save to disk and then it'll render it for you right so now everything's cached out uh we have a scene here as you can see if i do that you can see the interior detail has been activated and it's all cached out and so i've got is the rbd one and then pyro here we actually need these we'll blast them up now i'm going to assume if you're trying to do rbd you know how to render but just in case i'll go quick quickly so um so for the pyro we're going to want a fireball shader just scroll down you can use billowy smoke um or most volume shaders to be fair i just prefer fireball uh you can change like the color mode so in this case we don't have flames but uh if you did have flames uh i think physical black body color tends to give a better um result so if we just whack the uh density up to two as a start and then also a shadow density is two and straight away this will give us a uh an okay result i think so if we just attach this as a material smoke uh we're looking around a minute um for the the rbd stuff um i'm going to take strip just because i've i've cached it all out as one big file um but if you want to be a bit more specific you could cache that out separately um but for the sake of this i just going to keep it as a a basic lambert type shader so here is our uh mantra node um for the sake i've shown you how to set up or drop the fresh one down i'm going to change it to frame range i think i'm just going to do like 51 frames um very precise i don't know why i went to 50. i'll go 50. and then change it to the camera two which will be this one here which follows it let's see because it's quite beefy cache here it won't script the timeline as smoothly as you want but it's not a problem and then next i'm going to allow motion blur you can change this to physically based rendering um i don't think the results that different uh yeah i'm just going to hear it ray chasing why not but i think physically based rendering is somewhat might be a bit quicker but i have an rtx card so should be fine and sampling wise i'm going to leave it at three because this is a tutorial not a final render and this sort of digital global sampling rate and then you can go in here and sort of tweak specific areas um then finally if we go to this pyro enable velocity blur under the sampling and this is just so that the motion blur will take into account the velocity here um you can do it with the the geometry as well here um but i think with geometry it does it by default so we should be fine all right quickly before we're gonna lower this text let's go back to one and just to see what that looks like to start because i think we could get away with it so if we go to the render view or we select our camera and hit render let's see what it looks like so i just rented this little bit out um i think we're gonna settle with it obviously you can go in adjust the shader texture everything change the render sends uh whatever you want to do but for the sake of this i'm gonna render this out as a sequence which you can do by going to the render node i render it to disk or go to render and playlist for renders and then just hit render template but yup that basically sums up this tutorial um hope you learned something uh thanks for watching

Channel: Ryan Shepherd

Views: 14,689

Rating: 4.9911699 out of 5

Keywords: Houdini, Maya, Test, R&D, VFX, 3D, CGI, Adobe, Fracture, RBD, Rigid Body, Simulation, Ground, Destruction

Id: _hnO2kbXNE8

Length: 62min 12sec (3732 seconds)

Published: Wed Jan 06 2021