Blowing up cloth

Cloth, a 3ds Max simulation modifier, was the obvious choice for simulating a hulking dollar sign tearing through its clothes. Tasmanians would be familiar with the resulting TVC, for those that aren’t - go here (sorry not a permalink) for a web resolution version of the animation.

Beauty pass:

After the dollar sign mesh had been created and animated, John, the studio modeler, created a cloth mesh covering the dollar sign which he broke up into pre-torn segmented elements, this was done as a way to create a tearing cloth effect without actually tearing the mesh in the cloth simulation.

Once the cloth mesh was created, it was time to prep them for cloth simulation, the first step involved skinning each cloth element to a copy of the base dollar sign mesh using the skin wrap modifier, this allowed the cloth mesh to inherit the motion from the dollar sign, following it’s mesh deformation as it animated.

Skin wrap setup:

The actual cloth tearing event did not happen until about half way through the animation, so the cloth only needed to be simulated from the start of the tearing cue in the animation.

Each cloth element had a cloth modifier applied and a custom cloth preset was loaded - established and tested earlier in a test scene using primitive objects version of the final animation.

After all cloth settings were double checked, the dollar sign base mesh copy was then assigned as a collision object with offset set to 0.5, offset being the space allowed between the cloth surface and collision object surface.

Cloth preset:

Each cloth element was then selected and preserve constraints were setup by selected vertices on the area of mesh which did not need simulating. Because the skin wrap modifier was used, the preserve constraints allowed the cloth mesh not affected by simulation to maintain it’s animated state. At key points in the animation, these preserve constraints were turned off, allowing the cloth to fly free from the dollar sign.

Cloth constraints:

One of the main problems, which occurred during the simulation process, was the motion the cloth inherited from the dollar sign. It was so great that the cloth elements (as they separated from the dollar sign) did not fall back down, instead they flew out of the camera’s view. In order to counter this, an exaggerated gravity space warp was deployed, animating its strength value in order to get the cloth elements to fall back towards the ground plane as they were torn off the dollar sign mesh.

Once all the cloth elements were simulated, it was evident that the collision detection had failed in certain parts of the simulation. So to fix this, an edit mesh modifier was used to adjust any cloth elements intersecting each other so that it was not obvious to the viewer that cloth elements were penetrating each other.

Complete cloth simulation:

Once the cloth animation was finished and approved by the studio director, a HSDS subdivision modifier was applied to the cloth, making it appear smoother and more cloth-like.

The whole animation was then signed-off and sent for rendering. All I had do now was hope the client liked it (which of course they did).