Mesh

The mesh body part type is the most complex body part type. Mesh body parts can be created in any 3D modeling package such as Blender (www.blender3d.com, a free 3D modeling tool), Maya, and 3DS Max. However, the mesh has to be exported (converted) to the Wavefront object (.obj) format to be used in the body editor. Also, the mesh has to be converted to the Ascii II Scene File format (.ase) to be used in the simulator. When you first add a mesh to an organism it will be a box. Once you select a mesh file the box will change to the mesh that was selected.

A mesh is primarily used when geometric accuracy is desired, however there is a trade off in speed. That is, the more complex (geometrically accurate) a mesh is the slower the simulation will be. This can be offset by using collision meshes. A collision mesh is a simplified version of the graphical mesh (think convex hull). What happens is, the detailed mesh is used for drawing on the screen, and the collision mesh is used for all physics related computations. Typically, a collision mesh should have around 25% of the polygons that the graphical mesh has; However, it is possible to use the graphical mesh as the collision mesh. An example can be found here.

General Properties

To see a description of the properties common to all bodies follow this link

Mesh Properties

These properties are specific to mesh only.

Collision Mesh File
The collision mesh file also has to be an Wavefront object file (.obj). Usually the collision mesh is a simplified version of the primary mesh file to help speed up the simulation. If no collision mesh is specified the graphical mesh will be used as the collision mesh and the type will be regular (which results in slower simulations)
Acceptable value: Any Wavefront object file.

Collision Mesh Type
Determines if the collision mesh type is a convex mesh or a regular mesh. A convex mesh is a mesh in which there are no folds, tunnels, and other concavities. Convex meshes are preferred since they allow for fast and efficient collision detection The grasshopper above is a convex mesh. A regular mesh can be any arbitrary mesh, but caution should be taken when using a regular mesh since it could have folds, tunnels, and other concavities. These make it difficult to find quality contact points during collision detection. and can lead to simulations that are less stable than desired.
Default value: Convex (unless no collision mesh is specified, then the graphical mesh will be used as a collision mesh and the type will be Regular)
Acceptable values: Convex or Regular

Mesh File
The Wavefront object (.obj) file to use in the body editor. These files are usually more detailed than the collision mesh file.
Acceptable value: Any Wavefront object file.