Vellum Cloth Basics | Sara Rascon | Toronto Houdini User Group (THUG) | Nov 2018

hi my name is Sarah roschin am a technical artist at side effects and today we will look into the velum workflow for paneling Clark as well as draping and material looked up using Houdini's 17 noon vellum solver so here we have a very simple dress we will start by making our own by scratch so we dive in we're iron we already have our geometry that will be the collider so the first thing is that we will draw a curve we want to front view so it will be space tree I will enable the grid through 9 a snap to the grid and start drawing my shape it doesn't have to be perfect so this is good next we are going to set down a resample node and if we see from the tracker we can see that we have way too many points is not very smooth looking so with our example we can now have less points if we're not happy with this then we can simply keep adjusting until we have we find our sweet spot so this works we can create a edit node and edit the points that we don't like so here sorry I'm just going to quickly readjust this and set it back to origin to the middle and just readjust these guys really quickly there we go so after we have our one side we will mirror and because our shape needs to be a closed curve right now it's just two sets which are separate we will use fuse to fuse both of those so now it's just a single closed shape to create the clawed geometry we have several ways of doing so because now we are using a custom shape we are going to use planner patch from curves which is this guy which will fill in our geometry another way that we can create cloud is that we can use a planner patch which is simply just a shape sorry a regular planner patch there we go which we can use to create a shape it is a from set of defaults which is rectangle trapezoid a circle and the ring we can also create pleats using also the planner pleats up so the way this works is that we can make patterns so if we connect this here and we set the proper orientation we can do this way it needs more adjusting but it it's just the idea so now that we have the shape of our dress we can say oh maybe this is way too is not enough primitives so we can resemble the curves as well so because if we do don't do it every sample this we'll just use the default the previous point count of the silhouette but if we use resample curves we can fill in this area so that maybe that's good enough 24 yeah it is okay so now that we have or plan a patch from curves we can say that this is our front we can copy this node by clicking sorry by hitting alt key dragging underneath it go this will will be our back so we're going to set it a rearrange it properly in relation to our mannequin so we are in our transform shop we bring it a little bit more forward I'm going to turn off the craters nap and then once more we're going to position our back we're going to reverse just a reverse node so we can fix the orientation that's better and now we are going to merge both geometries so we can have one single piece now what we can do is that we can we can create our clot constraints so if we type bill and we can see these several setups that are useful for creating for example here the a balloon Claudie can be green or hair soft bodies but right now we are going to go with configure clot so the first thing we will notice is that we have three inputs do we place down a null we can tell that the first one is actually just for geometry the second one will be or constraint network the clock configure what does history creates the distance constraints and also demand constraints the way this works is that if I'm going to make really quick drawing here so we have a set of points which are going to represent or geometry so this is just going to be like the triangles we have I'm just going to simplify it a little more and we're going to make another one so we have our points so for a distance it's very straightforward what this does is pretty much how far away from each point to point are able to stretch pretty much this is going to be the stretch stiffness for distance constraints and for the bend as you can imagine is just the rotation so what you're what we are seeing here is both distance and Bend constraints what we can also do is that we can if we sit down sit down just a volume constraints we can see that we can default this distance along edges and here we can see here we placed on the know there we go and if we change it to bend across triangles this is how it looks like so now that we have our configure clot plot what we can do is that we need to first make sure that our scale is correct by that I mean not only just the scale in relation to your mannequin to me to Maura to beat the believable size of maybe I don't know one meter and 6070 it just depends but I what I also mean is that for the thickness of the clot as well so if we go into volume post-process this is meant to do more smoothing out the details that we want or just post processing or claude after we simulate but what this is helpful is that we can also use this to visualize so we can be shall I sort thickness right away from here and we can see that maybe it's a little too big so what we can do is that we can just decrease it a little more and so it's not too large that's better and now we create the volume drape we have two balloons solvers here one is the default William solver and another one is the vellum drape which is this one the AL develop driver the only difference is that it has more handy tools to for us to be able to stitch on the world to create I guess out sorry for us to create or claude de belem solar is just pretty much tease the default version is useful for all sorts of simulations developers rave submission before it allows us to stitch and world or clutch so I want to do is that we want to attach this side to this side and these straps as well so if we're going to solver we can see that is the same options and sweet you here but the with the addition of forces tab that we have the air track velocity damping and for the draping here if we check weld additional seams we can now start selecting which edges or points we want to sorry we want to stitch so I will go I will do all of this in just one go so I will select first different part and now the back there we go so this will be our stitch deed sorry this will be the stitch and well constraints so if we hit play what will happen is that well it's going straight into the mesh so what I haven't mentioned here is that the third input actually is where the collider will connect to so we go back to setting a null down and we go to the third input we can see that is just showing the collision the collider geometry so now that we have it we hit play is still going inside the map the geometry of the mannequin so we have to do a couple of adjustments here if we go into world properties we can see that we can do the welding frame delays so what this means is that when it goes into frame 20 in the frame 10 is where the welding will actually happen there we go it's actually sorry so this is on frame 12 is where T welding is going to happen this is because there is how steep its first attracting one side to the other just as a stitching process and the welding is where it starts to fuse so this is actually working against us what we want to do is right away we want to snap the clot to one side to the other so this is more well-behaved and it doesn't go through the mesh anymore one thing to mention is that this solver doesn't actually use gravity until the welding is done so during the process of pretty much the attraction from one side to the other of the seams it the gravity won't have an effect so it won't sabotage pretty much or draping process so these works maybe we want to have a smoother looking fabric so we can go back to your volume constraints so here is where we apply pretty much the properties for material form acid we can leave it out default is mostly relevant for in cases where have several pieces of cloud and there's several interacting so it can be maybe one fabric appears to be heavier than the other so this is just relative between the several pieces of cloth so in this case mass of 0.1 is fine it's the default it works very well so we already have our thickness next is the track which is how pretty much to behavior for flapping behavior the default works well for pretty much most cases for pin animation is where we want to as the name suggests we contain certain points to freeze them into place so we don't need that because here we just want to do the stitching and welding so here we have the stretch stiffness as we have mentioned before so what this means is that the default in Minister is actually this stretch stiffness is infinite but this means that the cloud is never going to try to be stretchy or it's going to be something more like liquorice for example what this is means studies the card is not going to try to stretch the damping ratio both for Bend and stretch what is does that helps lead out a little more energy from the simulation if cut maybe seems a little too lively in you may need to adjust the damping ratio a little bit some for the most cases we really don't want to go above 0.1 because it will start to actually avoid us to be able to enforce or constraints in this case the ban constraints or maybe we want to have lower strata stiffness so if we bleed too much energy it actually will work against us so for this case the default is okay the rest length scale is acid so this is just it right now it's default 1 which means that this is just going to be the same size if we put it lower maybe 0.9 in means that it will shrink by so it's going to be 90% of the size of what it was so one is okay compression stiffness so here a compression steam is default for this sort of cases is it works okay if we are using a very high resolution geometry for example you want to have more intricate false or more detail we want to have a higher resolution so we need to increase this much more so these will be as much as it can be to enforce the original distance constraint so compression stiffness is actually the opposite is how much one point can shrink pretty much to worse the other one so it's pretty much this how much this space can shrink and contract so we have very high compression stiffness it will enforce this original distance we have a lower one it means that it can contract a little bit more so if we have a very geometry that is more on the lower resolution side it means that it when it bends it will not look like people certainly want to look like cardboard or very quickly it will look much smoother because each point is able to shrink a little bit more towards each other without having like this sort of like Jerry Luke but if we're using higher resolution then we definitely need to increase this so for this a default works fine you can also enable warp and weft which is the stretching the y and x direction we also are putting the groups of the constraints that we are creating from this node and same for the Ben stiffness the T default is relatively soft so if we want more region material we might want to go something I mean a little bit more higher for for this we actually want or address to be more soft looking so we can decrease it even more in some cases we can go as far as point zero zero one since it as I've mentioned like it also depends on the resolution from your cloud so now that we have it to be a little more softer we can see that it now falls much more like it kind of bent more so it will disable to reference so this is our very simple dress what I mentioned here is that we can see that it actually goes up and down and then it settles and in this case it works nicely we want to stop like we only care about these later frames because this is going to be your new rest geometry but maybe we have cases where we don't want it to have like too much energy because maybe it's going to upwards your place where we don't want so what is very very helpful is that on the forces that we can simply increase drag and velocity tamping so these will kill any excessive or very sudden movement a clot may have also the one thing to mention is that the balloon drape actually has at a lower timescale so if we set it to one it's as if the assimilation was at full speed so in this case of at least for most cases for the drape we actually just want to have a little bit lower so it can be 0.5 the default is point two so in this case it was just perfect it worked very well so now that we have our very simple dress already I will show you let me look for the video I will be moving on a show in the process on how to dress the flamenco dress for this nick peak for belém belém tools for 1317 was done so here is the dripping process it was done in an additive manner so first it was the top then the frills which are double as you can see here and they we are doing the under skirt and the top skirt so this is the full sequence so this is actually up in this case we are have the underskirt in the red dress with any habits so here you actually have another layer underneath the main skirt which is the yellow one as you can see here so it actually handles the multi layers very very well we will go into how to in how to adjust the layer shock so what this does is that it actually makes the faulty layer underneath tuned to only affect the one on top so the one on top will not try to interfere too much on the bottoms the way this works is that it simply increases the mass of the petticoat Alice underneath so this is very much essentially heavier than the one Studies on top and we can also control how much this effect has the layer shock of the underneath layer that for they want at rest on top we can you can just disable it or mimic as it was done in two different passes so this is the setup for the for the dress is the same exact concept in here I have the silhouette of my t-shirt in this case I didn't even have it completely perfect I was rearranging on Kryon just to my front view so here I just flattened to a scale of 0 and said access and same as before just few stood the only thing that is a little bit more different is that I have introduced here reference these two notes and turn off my crazy hide my geometry I have made two additional lines inside my silhouette so the cool thing about panel planar patch from curves is that it can actually make straight lines if we wanted to so I noticed that when I was making the UVs for the t-shirt and the rest of the dress I noticed that while I had this jagged line stud2 triangulate that were triangulated from the planar patch which was not very it was not desired because these seams were going to be Jaggi so here by just making the line which is not intersecting to the other side it has to be inside so it doesn't matter for this space because it will create this straight line anyway just to to complete it by itself so I will have these straight lines sorry as you can see here which is very helpful for not only us but also for stitching maybe you want to make like a pocket here or in some other area and it's going to be a straight line so now that I have my paneling done I would go into perspective go back to goes to my mannequin the bellowing cloud constraints is very simple it just had like a very low thickness and very low Bend as well very at least compression stiffness is going more on the high side because it's more dense so we can keep or details from the wrinkles because as we mentioned before if we don't it's just going to smooth out because it's going to contract a little bit more so we gone to the vellum drape already loading from a piece that was already simulating so we can see how it simulates and hit cancel so we are just receiving from a little frame here if I uncheck it we can see like from the beginning these are my stitching we hit play this is more than enough for us so now if we just face the frame is just going as the name suggests is just going to freeze this frame even if we are in first frames or any other frame so this is helpful just to freeze that so next we use our building post process that we have seen before here I'm applying the walls what is does that is just fusing the worlds that were before it will just trim em at the constraints so if we try to simulate this we see that it's just static already but if we simulate this again what will happen is that it will fall apart so what we want to do is that we want to initialize our geometry by applying the world we're just fusing everything so we have have our standalone geometry without having to redo or welding constraints over and over the next step I'm making the frills for the sleeves which are to actually use double slips but for the frills as you can see it's two shapes and we have a thinner geometry which is actually frills on top of rails so the way I did this was to see simply create a planar patch which was very straightforward same as it comes that before I just died in and added like a line here so it's useful for UVs so I don't have like Jackie seems and then I used a band transform grouped it and mirror it so it's around the arms and same thing only thing was sorry I created one planar patch and just top look at it and just made like t wants on top and then lighter two ones on the bottom so we go here and that's how it looks like one thing to keep in mind is that I made an additional group here here I'm just selecting the edges that are going to connect to this leaf as we can see here or triangles are very large here because we have a lower amount of point on these leaves of this area so we go back to the sleeve and we can see in here that we don't have like too many points so we have here more than these leaves it's just going to be leftover points are not going to stitch anywhere and just going to be floating in there so if we try to stitch this large triangle to this one over here it's obviously not going to be very perfect so I'm just grouping these edges and then promoting it to primitives as you can see here we have this row of primitives so we're going to shrink these seams so it matches better to do size of the triangles we have already on the shirt so we make sure to initialize our geometry we already have this shirt but if we middle-click we can see that we already have 29 point attributes so this is way too much and actually some of these attributes may actually have an effect on the new simulation we're going to have a good practice is to simply clear all attributes you don't need and then while I use a clean sup which is very straightforward I'm just getting rid of all attributes except my color and this attribute VM cos angle so if we were to get rid of this guy you will notice right away that it's very jagged looking is the same exact geometry it's just the shading that is the difference it's just moving the clock you have like more pleasant not so tin foil kind of look so I'm grouping once more my sleeves on where I'm going to stitch because if I take a look here we have some of the seams for the grouping same but for I just wanted to be to be more straightforward here to have to include the right sleeve and the left sleeve then we create once more or velum transfer clot which is the distance and Bend constraints and here what I'm actually doing is time and creating these constraints to make the top to be static I don't want this section of the car to be the t-shirt I want it to simulate I want to settle down a little bit more or to flatten more against the skin this is just perfect for me so what I'm doing I'm just selecting tick group of the geometry that I'm going to simulate which is two points and then I'm I'm pinning to animation these very same group so this actually will look closer we can see that we have all these constraints these spheres on on the entire top geometry which is just indicating that is going to freeze into place it's just going to hold its current position at this point and it's going to keep it throughout the simulation next we're creating the cloud geometry for the top layer and the bottom layer of the sleeves I could simply also make just use a single balloon constraints a configure cloud for the entire of the remaining clutter we have here I just wanted to have a little more control for experimenting and see what works what isn't so this was actually just turned out to be the same exact settings as the one on top next we are doing a distance can along edges the distance constraint so what we can see here is that I selected the primitive group that is from the edges that we talked about earlier these triangles I want to shrink because otherwise my shirt will actually end up looking like this so this is my sleeve of the t-shirt so in my triangles are this size and if we don't shrink the frills but this will happen is that these triangles will remain very very large while the rest will actually be very small so this will definitely this will for sure stand out so to fix that I'm just using the distance along edges to have all these edges and um decreasing the rest length scale to actually to be just at point three of a thirty percent of its original size is a sorry to set the rest length to zero will actually make it implode on itself so we want to stay to a value above 0.1 at least and this is the result next we move on to the rest of the skirt we're making a group for where it's going to stitch in this case then we are once more applying the worlds of fusing all the walls we have already done and then I'm initializing the geometry again just to get rid of all attributes except the ones that we really really need and here is the layout for the underskirt same thing as before we said static all the ones that we are already finished and create the cloud constraints for the various part of the skirt so all these smaller rectangles are around its same as before is the planet Vegeta has been has been bent and placed around the mannequin this will connect to this will be stitching to create a frill skirt so we see the result this is how it's looking we apply wells we initialize it again for the entire geometry and then I have the rest of this Kurt because this is just the underskirt the petticoat so we want to finish the one that is on top which actually has even more frills this model frill on top of a larger fill so I'm just grouping just for organization and then making the constraints for the the various part of the new skirt and setting the static again and this is the result so it may look a little bit overwhelming at first but it's just a very simple procedure of just in just a process of adding and adding more and more steps of the tripping so once we are done with this we move on to your cloud setup which is more action more simpler in a way that we only have one set of constraints for the simulation this is for the animation sequence of the girl that is dancing so here I have the have volume cloud constraints for the main part of a dress except the underskirt and the frills because we I wanted to Springs to have a little more stiffness I wanted to not have like too fluffy as the rest of the dress so here I'm isolating the petticoat the frills and what here I also need to do is I need to help te dress to hold a little more of its shape if I were to simulate this normally it will eventually try to you may have a case where in my sleep to the other side too much or something like that or lose its shape so here I'm attaching just the color in this case you can see here we are touching the geometry or well the points of the dress to the mannequin so what I'm doing here is that I can attach the constraints to have like completely flat against the skin but I wanted to have a little more freedom I wanted to dress to be able to take color part of the dress to be able to shift around to move a little bit it doesn't need to be like look like it has been glued on so I have kept my rest length scale to 1 if I were to decrease it to maybe 0.1 it will snap back to its target position so pretty much these lines will contract same thing for the sleeves because I noticed that when her arm will lift the sleeves will collapse by the way - it's the shoulder area so I wanted to enforce this shape I didn't want to roll up to her to her sleeve too much and we're here I'm also doing as I'm trying another attach to geometry constraint but in this case for this entire area what I notice that well if you look at here sorry there you go we can see that we have all these small folds that are happening here so we want to keep these folds her to be attempt to be consistent throughout the simulation as the girl is dancing so this is just a way to help the dress to hold a little more of its shape you can see that it has a much lower stiffness we can go even more like lower down to 1,000 or 111 it's just going to be there and assist the cut to stay into shape which is better than not having these constraints so here what I'm doing an access that well here we are previewing the pins that we are using for the touch 2 geometry but what I'm doing here is that if you look at the color we can see that this is has a lower value than the rest so I'm masking using the paints up so I can paint attributes to the address directly here all I'm doing is I'm saying that the armpit area is going to shrink using rest lengths so on but on the primitives you see ya on the primitives so here I have an attribute wrangle with AB expression just to averaging the scale so it will shrink only firmly and you can see it here and this is free matcha tea set up the reason I didn't wanted to paint a lower rest length here is because I noticed when her arm went down well they're very large folds will appear so it was not very pleasant to look at because it was very very noticeable fold so what needed to be done was just a simple way of painting the attribute here to instruct her wrestling to shrink out to be smaller than the rest of the dress so the weight is was painted was that it's going to be a mask of one the entire dress is going to have the rest length position of one except in the areas where it's going to turn into 9.9 which is going to be the 90% of its original size just on the armpits so it's going to shrink closer to the skin so now that we have seen the process for the dress I'm going to talk a little more about how to do material look tab for different cloud types such as silk in here this is denim and here is leather so silk has much more fine crinkles the name is more a little more angular it depends on obviously on what exact I'm sorry so silk has more intricate amber soft-looking false while denim is more angular and more coarse and a little bit more stiffer and the leather is almost has like a rubbery property so it's a very large false as you can see here a very smooth looking so we move on to our setups quickly and here I have the set up for silk what I did here was to just I just have a planar patch here I transform it and then I fused these sides which can be seen here in this area because otherwise it will be an open darkest we can see here it is very close to each other but if we simulate week we will see immediately that it will come apart this area so that's why I'm fusing this side which is the right and left side on the planner patch the main advantage is that we can make our groups from our seams in a procedural way we don't have to reselect and recreate our groups here so we change the edge lengths to resolution of our skirt it will keep the groups on each side so we move on to our LM constraints is very very low stiffness and the high compression stiffness as we mentioned before because we have a very dense geometry so we are using attach to geometry to attach to the waist using a low rest length scale because we don't we don't want to keep this original distance we want this point to snap to the waist and then lastly I'm selecting the edges of the hem because if I were only to simulate using the attach to geometry it would punch up at the waist very noticeably so it will look very crumply look here because there's too much excess material it may be desired for specific styles but here I just wanted to have like completely close to the body as if it was an elastic hem so here I have the velum shoulder it's two substeps in here and 500 constrain iterations the rest has been left to default so the only thing we have increases substeps and constrain iterations so here have the cached simulation so this is silk here I'm using the vellum post process to smooth out the final geometry we can see you know how noticeable it may be there's a very very subtle difference but it helps like instead of using or smooth sup we can use balloon post process and use spatial blur instead next is the denim we start same as before we're using the vellum configure cloud constraints and the difference here is that I have actually decrease the compression stiffness a little bit when we can leave it up to same as the silk but it's just a matter of experimenting with your your exact piece of cloth so it's just finding what it works best and where you want to how do you want it to be very sort of say do you want tea it falls to be very intricate so helps or like a more crumbly look or is it going to be smooth so I have a higher stiffness of one is not that much but it's a little more than your silk and most importantly as I have enabled plasticity so the way plasticity works is that it will update its current rest position so what is means that it will not try to go back to this shape as it was on the silk which is what gives it its very soft soft falls like it's yeah like this flexible material so for the denim we actually want to have a style that is more crumply in a way more more angular folds so the best way to achieve this is to simply enable plasticity we have a very low threshold so it will enter into this new configuration much quicker and more more easily and using a very high rate and high hardening what this means is that some materials when they're they're bent they become softer others when become bent actually become harder so I wanted to actually start to harden over time which will enforce the Falls that happen as it's going to be draped same as in the other example I'm just attaching to geometry I didn't use the elastic hem hem just see attached to geometry and if we go to our simulation and actually what we can do is that if we connect or a volume pulse process and use the visual eye stuff we can actually visualize or the bent plastic flow so this is pretty much to visualize how much of an effect what is so if we hit play we can see the how the bend plasticity is being activated the red means that is it started sorry the visualization goes to the max Bend plastic flow so maybe there's too much red here so we want to isolate a little bit further just to check the area after we're bent the plasticity is being activated one thing to mention is start only using the plasticity on the bend constraints so this will activate when it's going to rotate if we were to use it on this stretch well it will happen is that it will stretch but it will keep that position the new position that is going to be the form which is why I didn't use this stretch plasticity next is the letter so is very similar to the denim the only difference is that we didn't enable plasticity because we don't want angular sharp Falls we want very smooth rubbery look so we have decreased the compression stiffness so it has a little more smooth look it doesn't enforce thick wrinkles as much and same stiffness of the denim a value of 1 then I kept my attach to geometry and my elastic hem so if we got 2 or simulation is way more defaults are way larger than the silk which is thanks to higher band stiffness and well what I could have gotten away with a lower resolution for the geometry in this case but I wanted just for the sake of showing how to create from the same exact geometry I have kept this large resolution but in this case it was it turned out to be well a little bit unnecessary because I'm using more resources to simulate this but if we have a lower resolution then we decrease compression stiffness here I start we can also paint attributes as I showed before on the painting the attributes on the top of the dress on the armpits so we can also paint bent attributes so maybe you want some area to stretch a little more we want this area to just the bottom part to stretch to the ground according to gravity but we want t sparked the top part to retain its stretch stiffness which is very high we don't want this to stretch so we're simply creating the attribute just to initialize and we are painting from our value from one to where the weakest part is going to be is going to be a value of 0.2 so one represents whatever input we put on the clock constraints so here we have a band sorry so you will have the stretch stiffness the default which is very very stiff and I'm using scale by attribute and I'm entering the stretch mask name that is being created here and also here so it will look at the simulation here I'm visualizing the stretch distance which is just going to show the parts where is stretching the most so if we hit play we can see that this area is the bottom area is very stretchy was well the top one is very stiff so this counts will be done for bent attribute and pretty much all others that for example the rest length or could be even the mass if we wanted to so next we will move on to creating a shawl here the main challenge was to guide the tribe to tribe sorry to guide the cloth to drape around her shoulders so the main challenge was well if I just let it simulate it would just fall down to the ground and never go around her arms I figured that I could use forces such as wind but that was not nearly enough to ensure that it was going to the places I wanted to so if we go here all this is is I'm just the process of creating the of creating my geometry here I'm using the planar patch for just set to rectangle and I'm bending it to the shape of a shawl which is folded in half so next here is some created hairs which is just lines being copied across on the edges of the planar patch that we have here so this is two parts merged together and now I'm same as before I'm just creating the constraints for the cloud the cloud part of the shell and another one using hair constraints so we type building hair constraints there is configure here so sorry so I have a very low stiffness on the share of 0.3 and also very very low band stiffness as well on the cloud we want this to be very flexible and very soft I'm also creating attached to geometry well this is here I'm just selecting the areas that are going to snap into the skin roughly or on the area where I wanted to position it to so it's just around her arms on her shoulders but if I were to use only this constraint well it will obviously just snap here without being guided over her shoulders so this is just a way to assist the simulation overall but it's not I'm not relying only on attach to geometry next is that we want it shares to stick to the cloud so what we're going to do is that we're actually going to pin and take clot to the hair not the other way around this is just a little trick hub very specific for volume so it's just the workflow tree needs to be we want to have an interaction of clot and here where the strings are in this case like to hear parts of different is freely bits it's going to be attached to a piece of cloth the clot is actually going to be welded to the hair so we have here the cloud pins which is all these red points that you can see here actually if I go closer you can see it better these are the gweld constraints so and so I'm spinning the these points from the grid to the first point of each hair as shown in the green part of these rings the hairs or it occurs next time using glue constrained so this is very very helpful it can also be used for clot but for this here example it what it does is studied mimics the natural clumping of the hair so if one here goes near by another then they will try to stick to each other naturally if we don't want to look like it's very silky velvety pieces of hair which can also be valid but in this case I just want to have a little more natural clumping so if we look our simulation here I have it already cached so if we take a look and I hit play oh I forgot to mention before we look at the result if we dive inside the volume solver I have created a pop wind so if we dive inside the volume sub solver because we also have the top version in this sub solar we can place down various various pop forces so we can use any of these guys if we want to for something like maybe a fan cone when in this case the pop wind work the best and I'm also having a little more of track so it will slow down the movement of when it's going to over her shoulders and then most importantly its time I'm using balloon constraint property I'm using this so I can bring this attached to geometrical strains as you can see here how to name them with a unique you have named them with a unique name so I can use this to refer to the group of these attached to geometric constraints and I'm going to animate this animated behavior of these constraints so if we go to attach of the geometry you will notice that I have used a stretch stiffness of 0 so what is me will start it's actually not going to do anything at all this is going to be the default starting behavior but what is going to happen on frame twenty five and onwards studies going to increase the stiffness to this amount so it's going to go back from not doing anything to suddenly snapping to the area where her shoulders and her arms are this is just so I can hold the shell into shape after it has been draped over her shoulders otherwise it would slid back into the ground so if we hit play you can see here that this is just up until this frame this is just the wind that is guiding it to to over her shoulders but it is after that is actually gravity is actually kicking in because i deactivated it rapidly throughout the simulation but it's also using the attach to geometry we will look here you can see it that is actually activating the attached to geometric constraints so it will hold the teach all into place then I'm simply using the balloon post process if I need to just to learn out the jaggedness artifacts artifacts you may have so this is how it looks and if I want to I can also make it a subdivision here to hug the wall or sorry not double to have a higher amount of polygons so if we are using special door and sometimes what happens is that the geometry may go inside the mesh because it's going to be smooth out so if we I will show you on this simple dress so we go here we show my mannequin so if we're going to my villain post-process I deactivated the thickness and if I want to blur it way too much you will notice that the world is going into the mesh now so what I can do to correct is as the name says the collision correction is to enable to detangle so this will push back and fix these areas we're just going to be self collision and yeah the intersection towards the mesh and I can actually say okay maybe one could be not not enough sometime the intersection we're still stuck inside so I can give it more passes if I need to and it will resolve and push the cloud outside the geometry the only thing is that this is only useful for smoothing the overall look of the cloud but not it will not fix self collisions that have already occurred during simulation this is just to correct this special blur and if we also want to well us have to before I can extrude my thickness and the visualize tab is very handy to just check general information that was already cached after the simulation but I can reference it anytime I want to so I can see my walls and pin the target stitch points or attach to geometry so thank you for listening to my presentation I hope it was very helpful

Channel: Houdini

Views: 35,168

Rating: 4.966713 out of 5

Keywords: Houdini vellum, Houdini 17, Sara Rascon, Houdini THUG, Houdini cloth, Houdini Toronto, Cloth simulation, Houdini cloth paneling, Houdini cloth material types, cloth paneling

Id: Mi7hWOubIFY

Length: 58min 32sec (3512 seconds)

Published: Fri Nov 30 2018