Houdini Vellum Cloth (Beginners) [Tutorial] | Emitting Vellum Cloth Bands + Shrinking/Shrink Wrap

in this tutorial you're going to learn how to make this [Music] before we begin go download the start hip file in the description below to follow along what's already set up in the file is nothing special this node here has the collision geometry and the transform node here is animating the looping rotation animation using a simple expression okay let's go back up and dive inside to the other geo node to start setting up our vellum simulation begin with a tube and set the type to polygon and radius scale to 1.75 and set the columns to 80. next is to remesh this tube and set the target size to 0.15 you might think why is this so large and also low poly well that's because we will be shrinking it down to around half of the initial size so we don't need a dense mesh then place down a uv texture node for rendering purposes and set it to cylindrical mapping and adjust the scale let's get into the vellum constraint setup so place down a vellum configure cloth the first parameter to pay attention is the thickness this is important to consider when you are doing cloth to cloth collisions turn on visualize thickness and usually the default thickness can be too much for small scale simulations so for our case we will set it lower to 0.15 for the density i'm going to make it a bit heavier by setting it to 0.2 as we are going for a slightly hefty rubber-like cloth okay scroll down to the stretch stiffness settings again there is no right or wrong way to do this but since we are aiming for a stiffer cloth that requires more effort to stretch out we will increase the stiffness scale then add a bit of damping and also reduce the compression stiffness to one and next this parameter is the key the rest length scale this is what will allow us to shrink or contract the cloth i'm going to set it to 0.45 this basically means that the stretch distance will be scaled down to 45 percent which results in the points contracting and coming together into a smaller area finally scroll down to the bend stiffness settings i'm going to slightly increase the bend stiffness scale and next reduce the rest angle scale to 0.75 all right in this section we will set up the emission system first of all create a transform node and connect it with the vellum geometry output on the left we will use this to randomize the rotation to give each cloth band a different emission location to animate this procedurally go to the rotation parameter right click and go to motion effects and select noise this automatically creates a chop net you can try pressing play to see what this is doing this default setting is not great so let's adjust the noise parameters first of all on your left window open the motion effects view i'm going to add 5 to the seed harmonics to 1 exponent to 0.75 and amplitude to 360. now hover the mouse over the motion effects view press space bar plus h to frame the entire graph all of these represent values that will drive the rotation parameter over time now go back up to sop level set the view back to scene view and press play again to see the changes this next step is not necessary but if you use redshift then you will want to put down a rest node and set to add normals this creates two attributes which are required in order to use the reference projection mode in the tri-planar node the way i'm using the rest node here is to add a unique texture projection to each rubber band in the redshift material now put down a point wrangler and don't freak out we're only writing a tiny bit of xcode to enable us to assign colors individually for each vellum cloth that is emitted inside the node create a new float attribute name it cloth underscore id and set it equals to add frame essentially what this does is when a new vellum cloth is emitted it will store the frame number of when it was born we will come back to this attribute towards the end of this tutorial the last steps are the usual two nulls to help with importing the geometry and also the constraints in the dopnet begin with an empty dopp net and dive inside for the initial setup start with a gravity then a vellum solver set substeps to 2 and constraint iterations to 50. next a vellum object and to bring in the geometry put down a vellum source and use the nulls we created before to import them into the solver the last one is a pop drag set the air resistance to 4 or higher as you wish as the shrinking motion can be quite fast by default for the collisions create a static object and emerge and connect them together in order below the gravity now select again the static object node and the soft path parameter reference the collider from the other geometry network named out underscore collider since our collision geometry will be animated click enable use deforming geometry for the settings for the physical tab it's really whatever you want but for the tutorial sake you can follow the values i chose lastly in the collisions tab you can either select use surface collisions or use volume collisions i chose to use volume collisions because it seems to result in a more sticky and gritty surface that i'm looking for you can switch in between them to see what i mean if you do want to continue with the volume method then in the uniform divisions set it to a resolution of 100. lastly set the offset surface to 0.01 to add a bit of padding to the collision finally we're going to set up the ability to emit some vellum cloth the first step is to go back to the vellum source node and change the emission type to continuous be careful here not to press play just yet because at this point a new vellum cloth will emit every single frame therefore we want to control how often it is allowed to emit in the activation parameter in here we will be writing some age script so what that looks like is dollar ff modulo 8 equals equals 0 and a double and operator and dollar ff less than or equals to 144 in other words emit every 8 frames until frame 144. that's all for the dopp net setup now you can go back out and try to simulate we're almost at the end now all we need to do are to take this raw vellum simulation and turn it into something that we can render to bring in the vellum geometry from the dopp net into sublevel we're going to use a dop import first drag the domnet into the first parameter and below set the object mask to the name of the vellum object node which is vellum object 1 and then set the import style to fetch geometry from dopp network in order to assign custom colors create a color node and set the type to ramp from attribute and set the attribute to cloth underscore id and set the range from 8 to 144 for now in the color ramp just select a preset and press play to see if it is working this part is all up to you just double click to create a new color and move them around as you wish for the redshift users to bring in the colors from here to the rs material use a node called rsuserdatacolor and set the attribute to cd next up put down a vellum post process turn on loop subdivision and i will set it to 2 for the best result and at the bottom enable extrude and i'll extrude it to 85 percent of the thickness to bevel the edges you can either use poly bevel set maximum normal angle to 80 give a small distance value of 0.008 and 2 fillet divisions or if you are a redshift user inside the rs material for the vellum cloth you can just connect a round corners node to the bump channel and make sure to enable consider same objects only and adjust the radius lastly to fix the normals add a normal node that's all and now you're ready to start rendering if you have any questions leave them down in the comments and make sure to leave suggestions for what tutorials you would like to see in the future before you go please consider leaving a like and sharing it with your friends thank you and see you in the next tutorial

Channel: Yu Fujishiro

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Id: Zoqo_6H9YYI

Length: 12min 0sec (720 seconds)

Published: Thu Apr 15 2021