Geometry Checklist

In order to get the best results out of a Carbon Cloth, Carbon Morph or a Carbon Tetra simulation, a good preparation of the meshes that will be used is essential.

Once a clean and basic mesh is created, please refer to Carbon Cloth Hints for further hints on how to choose geometry and set up a Carbon Cloth simulation.

The following list generally applies to both Carbon Cloth, Carbon Morph and Carbon Tetra.

Triangle Mesh

Quad meshes do not simulate well as they impose a certain bending structure. Therefore, Carbon internally works with triangle meshes. Even though it is acceptable to pass a quad mesh to the plugin, be aware that each quad is internally converted into two triangles by a simple split.

Clean Geometry

  • Remove degenerated triangles/tetras, non connected points, polygons with more than four points… etc.
  • Have uniform normals/triangle/tetras winding order.
  • Avoid inter-penetrating triangles/tetras.
  • Make sure not to leave any holes in the geometry unless it is actually a feature of the garment such as holes for buttons, tears, … etc.

Good Tessellation

  • Create a tessellation as uniform as possible throughout the object geometry. Avoid tiny or large triangles.
  • Avoid splinter (long and sharp) triangles/tetras.
  • Have the tessellation match the degree of freedom of the material, e.g. too high of a tessellation could give too silk-like of a result, and too low of a tessellation would make small folds impossible.

Divide And Conquer

  • Separate layers into different meshes, e.g. avoid connecting vertices on a shirt and a jumper that will need different materials and characteristics.
  • Separate accessories such as buttons, buckles, … etc. into different meshes.
  • Where a cloth/tetra has non manifold geometries, such as flaps or pockets, the vertices need to be shared between the faces where the two pieces of geometry connect, as this will always look better than being reattached at the simulation stage.
  • Avoid using disconnected geometry in the same cloth/tetra, and use multiple cloths/tetras whenever possible since that will take advantage of two nested layers of parallelism instead of one and reduce the initialize time as well. However this has no impact on stability.

Mind the Gap

  • Avoid tiny details containing points that will be closer to each other than double the estimated fatness of the cloth/tetra material.
  • Avoid folds or layers of cloth/tetra (including flaps and pockets) that place points closer to each other than double the estimated fatness of the cloth/tetra material.
  • If several layers need to be attached at the same position such as a two layer skirt at the waist, it is still best to separate them and leave a small space (at least the sum of the estimated fatness of each cloth material). Then use a separate binding node to keep them attached. This way the simulation will keep enough degrees of freedom for the connected geometries.

Note

  • Although it won’t show up the entire list of potential problems listed here, it is always a good practice to use the Carbon Cloth Guide Geometry and Carbon Tetra Guide Geometry tools to visualize and assess the suitability of the geometry for simulation.
  • Please refer to Geometry for examples and tricks on how to detect and solve some of the issues mentioned above.

Clean Animation

To ensure an easy setup and fast results for animations, it is important to have an animation sequence which is free from self-intersections/penetrations.

Using the Collision Analysis tool of Carbon Collider nodes helps to detect areas where self-collision happens during the animation.

Note

There are cases where it is unavoidable and even desirable to have animation which self-penetrates. An example for this an arm penetrating a character belly during the animation. Turning the belly into a deformable object using a Carbon Morph leads to the belly deforming and creating more realism than a simple animation without any penetrations.