Tearing nCloth

This tutorial will teach you how to tear or rip nCloth in Maya.

Set-up

Download base.mb. This scene contains a simple animation of an arm coming and ripping some cloth. The ripping simulation has yet to be done.

Go to window>settings/preferences/preferences. Go to timeline and set the playback speed to play every frame.

Geometry

The geometry that you rip greatly affects the way the tear looks. Perfect quad geometry looks too symetrical. The image below is an example of that.

By using a random geometry pattern, the geometry will look more like real cloth when it's ripped.

To get that geometry from our perfect geometry plane requires a few steps. What we're going to do is increase the poly count by dividing it, then using the reduce tool to randomly reduce polygons.

Step one - Select your poly plane cloth that will be ripped and go to edit mesh>add divisions...open the options.

Step two - We need to divide this three times, so set the division level to 3.

Now click add divisions.

Step three - Select your newly divided poly plane and go to mesh>reduce... Open the options.

Set the reduce by to 30%, check triangulate before reducing, and make sure all the preserves are checked. Now click reduce.

Now we have a nice randon topology.

nCloth

Now let's make the geometry in nCloth.

Step one - Select your poly plane and go to edit>delete all by type>history.

Step two - Go to the nCloth menu set, select your poly plane and go to nCloth>create nCloth.

Now we need to prevent this nCloth from falling out of the frame. Right click on the nCloth and go to vertex mode, select all the border vertices, and go to nConstraint>transform.

This will lock these vertices into place, holding the nCloth when you play the animation.

Tearing

To tear nCloth, you need to define the vertices that are tearable. Defining the tearable surfaces is as easy as selecting the vertices and going to nConstraint>tearable surfaces. You can select the vertices by hand, but for more organic way of doing it, use the paint selection tool.

Step one - select the nCloth. Click on the paint selection tool in the toolbox.

Step two - Now use the brush to paint where you want the surface to tear.

Step three - Go to nConstraint>tearable surface.

Step four - When you play the animation nothing should happen differently. The nCloth itself shouldn't generate enough force to tear the surface (more on how to set the force required to tear the surface later). This is where our claws on the end of the arm come in. Select them and go to nCloth>create passive.

Now they can interact with the nCloth. Now play the animation.

Editing The Tear

To edit the tearable surfaces, open the outliner (window>outliner) and select dynamicConstraint2. Then open the attributes editor (window>attributes editor).

There are a lot of different attributes. The most common one we need to change is glue strength.

Reducing glue strength will make the cloth rip easier; increasing the glue strength will make ripping the cloth harder. For this simulation, use 0.070.

Lastly we want to change the nCloth's properties. Select the nCloth, open the attributes editor, and roll down to stretch resistance.

Set it to 200. This will make our cloth less stretchy. Now play the animation.

Conclusion

Using these simple steps you can basically use any type of object that can be converted into nCloth. I have a youtube example below showing the same effect using different nConstraints and glue strength.

Good luck.