Multi Layered Cloth using Separate ClothFX modifiers

This is a simple explanation of the theory behind using one cloth sim to drive a collision object for another cloth sim.

The reason you would want to do this rather than have multiple layers of cloth in a single cloth sim is simple, speed.

Typically you would have the modeled cloth bound to a driver in your Master Mesh file that will have a pointCache modifier on it. Then you would run your sims on a Master Cloth Sim file from which you would write the pointCaches from.

In this example I am keeping everything together.

This "tutorial" is more of an explanation than a tutorial. It is to describe the "Theory" behind doing multilayerd simming. I will do a step by step tutorial with modifier stack snapshots and Cloth settings as soon as I can. I am very busy at work right now but I wanted to get this up for the people on the CGTalk forums.

 

This image shows a collision object for an arm. It is important to have a clean mesh when you run your cloth sims. It is also important that the size of your polys in your collision object are "roughly" the same size as they are in your cloth driver.

It is not a requirement but I find that sims go a lot smoother and there are less interpenetrations when the polys are about the same size.

The polys on your collision objects and more importantly your cloth drivers should be as square as possible. No long skinny faces.

 

This image is of the modeled cloth (in this case a cylinder with a little noise on it). You will be using Skin Wrap to "Bind" this mesh to the "Driver" mesh below.

 

Here you see the "Driver" for the modeled cloth. This mesh is unrenderable and is used as the "Driver" for the Modeled cloth. Simply add a skin wrap modifier to the modeled cloth and use this mesh as a bone.

Keep in mind that this mesh is going to be "Driven" by the Simmed mesh below. I will explain why you have a "Driver" between the modeled cloth and the simmed cloth later in this tutorial.

 

This object, which is a duplicate of the object above, is going to be the object you run the sim on. The two meshes need to be identical since you may be writing a pointCache on the "Simmed" cloth to be loaded on the "Driver" cloth.

 

Here you see all the objects together. The "Driver" object is in box mode for clarity.

 

Once the sim is run you can see that the Rendered cloth is being "Bound" to the Driver and the Driver is being "Bound" to the simmed cloth.

The reason there is a driver is so you can fix interpenetrations with poly select, push and relax modifiers without putting modifiers above the ClothFX modifier.

This way you have your ClothFX object independent of any other meshes you are working on.

As a side note there is a relax and a slight push applied to the "Driver" mesh to make the modeled cloth look "cleaner" without taking the detail out of the modeled cloth. If you put a relax on the modeled cloth you will smooth out the topology.

 

This is an image showing the collision objects for the second sim.

The Yellow mesh (in box mode) is the simmed object from the first sim. A snapshot is taken (red cylinder) of that object and it is skin wrapped to the simmed mesh.

At this point the simmed mesh from the first sim is hidden.

You will be using this new mesh as a collision object for the second sim.

 

Here is the modeled cloth for the second sim. You will bind this to a driver then bind that to a sim mesh as you did for the first sim.

 

Here is the sim mesh for the second sim (Yellow Mesh) and the collision object that is bound to the sim mesh from the first sim (Red Cylinder). The arm mesh is a copy of the original mesh and will have its' own ClothFX modifier on it.

You never want to have multiple ClothFX modifiers on one object. I am sure that it is possible but I prefer to keep my sims separate from each other.

 

 

These two images show the second sim complete. The red mesh "inside" the second sim mesh is the new collision object from the first sim.

 

 

 

These final three images show the two rendered cloth meshes together after the two sims are complete.