Tetrahedrons Versus Inflatable Objects

Carbon currently supports two main ways to simulate volumetric objects:

Tetrahedrons are three-dimensional geometric objects that consist of 4 points, each of them connected to the other 3, therefore forming a surface consisting of 4 triangles. In Carbon, their shape preservation is controlled via segment and volume compression/extension. For more information, please refer to Carbon Tetra and Compression/Extension.

Inflatable objects on the other hand consist of two-dimensional faces, which form a closed surface and gain volume due to Face Pressure. That explicit force impacts a face along its normal vector.

An advantage of using an inflatable object, which consists of a closed surface only, is that usually a lower number of primitives (triangles, quads) are needed when compared to a tetrahedralized geometry. This goes along with faster simulation times. The biggest downside of inflatable objects is that they are not volume or shape preserving. The following example shows that very clearly. While the tetrahedralized cube does not lose its sharp edges, the inflatable cube immediately smooths the edges.

This first screenshot shows that both geometries have the same surface layout.


Surface layout of the Inflatable object (left) and the Tetrahedron object (right).

The following animation shows the inflatable object, a Carbon Cloth, on the left and the tetrahedron object, a Carbon Tetra, on the right reacting to a spherical Carbon Collider pushed down on each volumetric object.


Inflatable object (left) versus Tetrahedron object (right).