Let’s take a look at the final examples of usage. First one is an animation of breaking ancient vase and the second one is just a breaking box. The second one is actually a test render which was made haphazardly but it reminded me ice bergs from Ice Age movie so I also posted it here.
How can we create cracks on surfaces?
There are several different ways:
- Paint them on the texture – great results but they are not real
- Cut your mesh first and then animate it – also great but complicated
- Create a crack during animation
- I’m sure there are even more methods but I’ve tried only these above
We will use the third one.
Objects to break
Create something that you want to have cracks on. In my case these objects were just a box and an ancient vase. I suggest to start with the box so create one with dimensions set to 350, 200 and 20.
Go to Shapes -> Splines -> Line and create an irregular crack path.
Create an NGon with three sides. Convert it to Editable Spline and drag one of its vertices away.
The easiest way to make your triangle follow the crack path is to use Loft but for some reason Loft cannot be animated. We can use Loft with PathDeform modifier instead which will make our cross-section grow and follow the path at the same time or we can use AF Loft plugin for 3DS Max that allows us to animate Loft. Second solution seems to be less complicated so let’s just download AF Loft plugin.
Once you have the plugin installed you can add an AF Loft modifier to your path. Pick NGon as a shape.
Set AF Loft’s amount to 0. Jump to the end of your animation and with Auto Key turned on change the loft Amount to 100. Your shape should now follow the path during the 100 frames.
Cutting a hole
Select a box and go to Create -> Compound Objects -> Boolean. Choose the Loft as the second operand. Your loft should now carve a nice crack in the surface during the 100 frames of animation.
There’s only one problem. This animation doesn’t look realistic at all. To solve this problem we can make it happen less linear. Undo Boolean. Move the time slider to the second frame and turn on Auto Key mode. Change the loft’s Amount to the value that corresponds the distance between first two vertices on the path (see image below). Do the same with the other vertices.
Apply a Boolean again and it should now break in less linear fashion which is much closer to reality. You can use the same technique to create more advanced cracks like my vase animation.
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