The Crytek Geometry Format (CGF) is the CRYENGINE file type used for static geometry. You can also create phys proxies for the CGF meshes using the same steps we explained in the previous chapter. Instead of parenting the proxies under a skeleton, here we will parent them directly under the CGF's parent group under its CryExport group.

It is worth mentioning that the CGF asset and its phys proxy's material IDs need to be in the same material group; otherwise, you will get an error exporting the asset. This is a requirement that we don't need to follow for exporting the Character Format (CHR) skeleton and its phys proxies.

The Character (CHR) format is used to export all the skeletons and phys proxies' data through a skinned mesh. We can't export an object as a CHR that is not bound to bones via a skin cluster node in Maya, which makes the CHR in that aspect similar to the skin (skinned Render mesh) file format.

In some older assets, the CHR actually represents both the skeleton and the skinned mesh. However the recommended pipeline now for creating characters in CRYENGINE dictates a separation between the two. Think of the CHR as simply just the skeleton and its proxies, while the skins are the mesh attachments for it.

The most common practice for creating the CHR in Maya is to create a simple mesh, usually in the shape of a triangle, and smooth bind it to an upper body joint such as the pelvis joint. The material used for the CHR mesh is a ProxyNoDraw material, usually the same one applied on the phys proxies. We will cover the process for creating a CHR in detail in the Creating the export groups in Maya section.

The Skinned Render mesh or skin represents a CRYENGINE compatible skinned assets file type. A skin can be any mesh that is smooth bound to our character's skeleton, which is represented by the CHR.

In older CRYENGINE versions, you would get a crash if you tried to load a character definition file in Sandbox, where there is an extra bone used in the skin cluster of the skin attachment and not found in the CHR. This has changed in SDK 3.6. If you add a skin attachment with extra bones to the character definition file now, those bones are extended to the CHR skeleton. We call that system the skeleton extensions.

It is important to understand that these extra bones are not being added to the CHR file itself. The process of extending the skeleton is done at the character definition file load time. The CHR file hasn't been modified, and neither has the character definition file.

Skeleton extensions provide great flexibility when it comes to a character's pipeline. It is common to use one CHR/skeleton for multiple characters in a game. However, it can get problematic if you have a more complicated asset where you need to add extra corrective bones to get the desired result. Without the skeleton extensions, you would need to add all of these bones onto the same skeleton. If you get even more complicated assets to skin to the same skeleton, imagine how cumbersome the process would be to have all of these joints that belong to different skins added in the same CHR.

The Crytek Geometry Animation (CGA) assets are simply animated rigid meshes where the animations are applied directly onto the geometries. CGA animations can be exported as .anm and .caf file types, while skeleton-based animations only use .caf files. By default, you export one default animation with the CGA asset. To have additional animations, you will need to export them to the same folder where the CGA asset is saved. The animations get linked to the CGA by using the name of the CGA asset as a prefix for the name of those animations.