This tutorial will teach you how to tear or rip nCloth in Maya.
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.
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.
Now click add divisions.
Step three - Select your newly divided poly plane and go to mesh>reduce... Open the options.
Now we have a nice randon topology.
Now let's make the geometry in nCloth.
This will lock these vertices into place, holding the nCloth when you play the animation.
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 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.
Set it to 200. This will make our cloth less stretchy. Now play the animation.
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.