Deformations

Vertex Cache Deformations

For FBX files with heavy deformations to the mesh, it may be more effective to cache the deformations to disk. In a big production pipeline, this gives the artists the flexibility to pass the cache alongside the meshes down the pipeline, and to view the static meshes as well as to bring in the animation from disk. When you export this mesh and vertex cache to FBX, Mari loads in the mesh, locates the cache, and loads in the geometry with cached animation.

Skin Deformations

In cases where the FBX file contains the skeleton deformation of a mesh, where the geometry is rigged by adding a hierarchy, this is bound to the mesh, and keyframes are animated to deform the mesh, you need to follow certain binding methods to ensure that the .fbx file is loaded into Mari correctly. The three binding methods you can use are:

• Linear/classic binding - the default binding method, where the position of a vertex is determined by linear interpolation of the weights of the surrounding bones.

• Dual quaternion binding - a binding method that provides an improved solution to skinning geometry, where the volumes are preserved in case of extreme stretching movements.

• Blended binding - a binding method that mixes both linear and dual quaternion methods through the use of a blend weight.

Using one of these methods, both the mesh and the associated skeleton is exported to the .fbx file and, when imported into Mari, this information is read and loaded into the final mesh with the deformation.

Note:  Mari does not display the skeleton; only the deformed mesh.

Cluster Deformations

Most modeling packages allow you to define extra weights on selected sets of vertices for a mesh, called a cluster deformation. Cluster deformations are supported by FBX at the point of export. Adding cluster deformations can work with skinned meshes, but you need to ensure that the order of input and output is correctly set up before exporting the scene to an .fbx file. Once the file is loaded into Mari, the mesh is loaded, the associated clusters are gathered, and the weights are applied to the vertices, before the deformed mesh is then loaded into the project.

Blendshape Deformations

Most modeling packages allow you to create duplicates of original geometry in order to blend between the original and duplicate using a weight. This allows you to achieve in-between poses, and is especially useful for altering a character's facial expressions in a production environment. You can then keyframe animate the blendshapes and export them to FBX. One the file is loaded into Mari, the mesh is loaded, the associated blendshapes are gathered, and the weights are applied to load in the final blended geometry.