Cinema 4D Quick Tip: Global Intersection Analysis for Cloth

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I was recently experimenting with a candy bar animation after I saw a Snickers Bar commercial.  I wanted to see if I could recreate the pull of caramel in Cinema 4D when a candy bar is broken apart.  I knew the go-to tool for this work would be the cloth engine, but a simple add the tag and see what happens solution was not going to work on this test.

Things didn't go as simply as I I thought they would.  Granted, I was only doing a quick proof of concept mockup. 

Fixing points in the Cloth Tag.

Fixing points in the Cloth Tag.

Making a cube editable then “fixing” the furthest points from the center of the “caramel” was a start.  Turning the Stiffness to 0, Flexion 1, and Rubber 100 were the obvious starting points.  I soooooo wanted to turn Rubber up past 100!  It was quite amazing the difference in results between Flexion 0 and 1. The Cinema 4D cloth engine can be as frustrating to fine tune as it is a godsend for simple cloth animations like a waving flag. 

Cinema 4D Cloth Tag Settings

Cinema 4D Cloth Tag Settings

Adding a Cloth Tag to a cube doesn’t get you the expected results as you would by adding it to a simple plane object.  Try turning up the Iterations into the hundreds and you will still get intersecting simulations.  There is help in the Expert Tab. Turn on Self Collisions and Global Intersection Analysis and your calculations will take a hit but you will get some better results.  They are simple check box solutions.

The Cinema 4D help file for Global Intersection Analysis is pretty vague in its explanation:

During animation, either intentionally or by accident, an area such as the armpit of a bipedal character can trap the cloth object. This can cause some cloth engines to come to a complete halt being that the engine cannot find a solution. Global Intersection Analysis (GIA) will find the best possible solution that will allow the cloth engine to continue its simulation.
— Cinema 4D Help File

Turns out Global Intersection Analysis was invented by some guys at Pixar to help with their cloth simulations.  See this link here.

My experiment included multiple Cloth Tags on thin planes to try and get the tearing of thin caramel strands.  If all you need is a brief shot you might be able to get away with a computer simulation of the candy bar breaking apart, otherwise shooting it for real would probably be a better option. There are many "table top" photography studios that specialize in this type of still and moving image photography.

Plane objects set to create strands of caramel.

Plane objects set to create strands of caramel.

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In my test I just added a simple material with a Bump Channel and Displacement Channel, but the Cinema 4D sculpting tools would be handy to add the ridges of a candy bar.  Using an HDRI for reflections also gave life to the caramel surface.

 

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