# Multiple Collision Items

Posts: 66
Not sure if this is the right form for it but I really wish we could have multiple Collision items. I believe that it would be really helpful in making clothing fit better.

• Posts: 78

This would also be great for those times where we want outerwear to drap over underwear, or a cape to go over a super-suit, any time there's a layer between the clothing having dForce applied and the characters mesh.
Sure, we can set the middle layer as Static Surface, but then how do we have coats over skirts with both having dynamic movement :)

• Posts: 66

This would also be great for those times where we want outerwear to drap over underwear, or a cape to go over a super-suit, any time there's a layer between the clothing having dForce applied and the characters mesh.
Sure, we can set the middle layer as Static Surface, but then how do we have coats over skirts with both having dynamic movement :)

It doesn't make any sense that this is not possible. It would add even more realism to clothing (and hair if we could get it to work)
• Posts: 874

Is this for dForce (simulation) or mesh smoothing (in parameters)?

For Mesh Smoothing, one thing you can do is have each layer use the layer below it for collision. Shirt collides with the figure, jacket collides with the shirt, cape collides with the jacket. You may have to play with the iterations of collision and smoothing to get a decent look though.

For dForce, you should use the collision layer parameter. Layer 1 is the closest to the figure and subsequent numbers are considered to be higher. So you could have the shirt at Layer 1, the jacket at Layer 2, and the cape at Layer 3. This should allow dForce to layer the clothes on top of each other.

• Posts: 3,142
JonnyRay said:

Is this for dForce (simulation) or mesh smoothing (in parameters)?

For Mesh Smoothing, one thing you can do is have each layer use the layer below it for collision. Shirt collides with the figure, jacket collides with the shirt, cape collides with the jacket. You may have to play with the iterations of collision and smoothing to get a decent look though.

For dForce, you should use the collision layer parameter. Layer 1 is the closest to the figure and subsequent numbers are considered to be higher. So you could have the shirt at Layer 1, the jacket at Layer 2, and the cape at Layer 3. This should allow dForce to layer the clothes on top of each other.

Might be a silly question but how does this work with underwear, for example, where there is a small area of cloth overlaid by a much larger area? For the most part, the "outer" clothing is touching the skin and not the undies.

Another question about dForce layers: should both items of clothing be dForce enabled? Could one be visible in simulation but not dynamic?

• Posts: 874
marble said:
JonnyRay said:

Is this for dForce (simulation) or mesh smoothing (in parameters)?

For Mesh Smoothing, one thing you can do is have each layer use the layer below it for collision. Shirt collides with the figure, jacket collides with the shirt, cape collides with the jacket. You may have to play with the iterations of collision and smoothing to get a decent look though.

For dForce, you should use the collision layer parameter. Layer 1 is the closest to the figure and subsequent numbers are considered to be higher. So you could have the shirt at Layer 1, the jacket at Layer 2, and the cape at Layer 3. This should allow dForce to layer the clothes on top of each other.

Might be a silly question but how does this work with underwear, for example, where there is a small area of cloth overlaid by a much larger area? For the most part, the "outer" clothing is touching the skin and not the undies.

Another question about dForce layers: should both items of clothing be dForce enabled? Could one be visible in simulation but not dynamic?

dForce layers should work fine for the first case (underwear), since you aren't giving it anything specific to collide with, you're just trying to help dForce by providing some guidance as to how the cloth lays on top of each other. Mesh smoothing would probably be less effective since if you set a pair of jeans to collide with / smooth over the underwear, it could poke through the figure's knees.

For layers to work, yes both have to be dForce enabled, however you would have the option of say using a dForce static surface modifier instead of dynamic. If you don't have some sort of dForce modifier applied, you won't be able to select a layer option for it. So say you had a kilt with a broad hard leather belt over it, and a cape. You could set it up as:

• Kilt: dForce dynamic (layer 1)
• Belt: dForce static (layer 2)
• Cape: dForce dynamic (layer 3)

[ Note the lack of underwear as no self-respecting Scotsman would be wearing underwear under his kilt. :-P ]

• Posts: 620

I would assume the ask is about smoothing though, since dforce by default is colliding with anything in the scene? And I don't think the surfaces need to have dforce applied if they aren't going to be dynamic, since, for instance, the Genesis characters are not. Unless I'm wildly misunderstanding what you are trying to do/illustrate?

• Posts: 3,142

I would assume the ask is about smoothing though, since dforce by default is colliding with anything in the scene? And I don't think the surfaces need to have dforce applied if they aren't going to be dynamic, since, for instance, the Genesis characters are not. Unless I'm wildly misunderstanding what you are trying to do/illustrate?

Yep, that's something else I haven't quite got figured out yet - what is the difference between a static layer and just visible in simulation? As best I can make out, the reason for applying a static surface is to be able to adjust a couple of parameters like friction - but without the static modifier, cloth will still drape over the object if it is visible in simulation, right?

A good deal of time in my preparations is taken up painstakingly going down the heirarchy tree and switching "visible in simulation" to off. Otherwise the sim just calcuates for everything in the scene and takes a long time.

• Posts: 114

Visible in simulation means whether the surface is used by the simulation at all. If it's turned off, it is not simulated OR used for collision. You would generally use it if you're having issues or to disable parts of a model that you've hidden by making them completely see through.

I would add that you can manipulate the parameters of multiple materials at once by selecting them at the same time, then toggling the parameter for them all as one.

• Posts: 48,546

Yes, an item that is visible but not dynamic is a static object - you'd explicily make it a dForce static object only if you wanted to adjust settings from the default.

• Posts: 57

I've been following the advice in this thread and trying to do a multilayer simulation of some fairly standard clothing - a pleated skirt over non-skintight underwear. In DS 4.10, the simulation crashes out after around 25% and DS shuts down. In DS 4.11 beta, after a similar time, it rather more politely throws up an error message, but will not do any further simulations until DS is restarted. Has anyone got a fairly straightforward guide to getting multilayer simulations to work? Preferably idiot-proof?

• Posts: 48,546

Did you adjust the collision layers (in the Surfaces pane) so that the skirt had a higher value than the underwear? And was the set-up clear of poke-through in the starting pose (the first frame for a timelien drape, the memorised pose for a static drape)?

• Posts: 57

I have underwear as layer 1 and the skirt as layer 2. One of the things I haven't been able to do is to eliminate poke-through due to the very limited adjustments built-in to the clothing. So do I HAVE to get rid of poke-through before attempting simulation? Is that what is causing the crashes? Not sure how I achieve this.

• Posts: 57

I managed to eliminate poke-through using Fit Control but when I ran the simulation it stopped with an error and all the clothing exploded!

• Posts: 48,546

If you select whichever piece (or pieces) you morphed and look under Simulation in the Parameters pane is the item set to start from the current shape?

• Posts: 57

It's set to 'use simulation start frame'. I'll give the other setting a go.

• Posts: 57

I tried 'current shape' and the simulation didn't even start before DS 4.11 beta crashed out.

• Posts: 48,546

OK, check (in as far as you can) that the morphs haven't led to the clothing self-intersecting, one bit passng through another.

• Posts: 57

I have tried this and it's very difficult with pleated cloth! Nevertheless I thought I had eliminated and obvious self-intersection but I am still getting an immediate crash on attempting simulation. I have tried to be a bit systematic about tracing this error to a particular interaction of settings and clothing but I'm afraid my tired old brain began to shut down. When dForce works the results can be amazing, even just the draping of a simple dress, so I shall persevere.

• Posts: 874

Another (somewhat slower) way to attempt mutliple layers is to initially only set the innermost layer as visible in the simulation, all other surfaces should not move. Then freeze the simulation on that layer, but leave it visible and add the next, then the next, and so on. This works better when you are not rendering from the saved position, but just trying to get the items to drape in place in the final pose.

• Posts: 684

Also make sure Self Collision is off, especially for the pleated skirt (which is going to self-collide all day long). This doesn't prevent self-collisions, it tells dForce not to blow a gasket when they happen.

Also increase the Collision Offset from 0.02 to 0.06. This gives everything plenty of room to bounce.

If an article of clothing is not essential to the scene (if the underwear is not visible), it's best to either hide it or remove it to prevent dForce explosions.

When using morphs/Fit Control to separate layered items, get as close as you can to ensure they're still not intersecting on the underside. Eliminating poke-through on the outer visibility does not mean they're not still intersecting. Use the Hidden Line draw mode, and the Magnifying glass navigation tool to inch in as close as possible, rather than the mouse wheel.

Lastly, if you use the Geometry Editor to creat new surfaces for outer layers that more closely match the coverage of the inner layers, you can assign them different dForce parameters.

For example, the area of the skirt that covers the undies would be Layer 2, while areas beyond the undies could be Layer 1, same as the undies, so it collides with the legs more naturally.

However, this is not as much of an issue as it sounds, in my experience, because even set to Layer 2, if nothing obstructs it, it hits the legs just fine. Layer settings do not operate in a Bounding Box manner.