Are there guidelines for creating game assets in Harmony?

There are quite a few things to take into account when creating game assets in Harmony. The most important step before asset creation is to decide on the export type.

Choosing an export type

The type of export you use will greatly affect the method of asset creation. For more information on the different types of exports, see What are the different types of game exports in Harmony?

• Rigged Animation Export: This type of export is ideal for light assets. It also allows for the export of information like rig hierarchy, Game bones, cutters etc.
• Frame-by-Frame Export: This type of export results in heavier assets. It allows you to use any Harmony tools to create assets, including production rigs and paperless animation as everything will be flattened into sprites during the export process. 

Because Frame-by-Frame export allows you to use any features to animate game assets, the rest of this article will focus on guidelines for the creation of assets for Rigged Animation Export.

Using cutters in game assets for Rigged Animation export

The Cutter node in Harmony is used for masking drawings using custom shapes. The game engine SDK implements both regular and inverted cutters with the following limitations:

• For a sprite, only a single cutter drawing can be applied when it is rendered. This also applies to a composite of multiple matte drawings. The game engine SDK will only use the first matte drawing during rendering and discard the others.
• You cannot 'daisy chain' one Cutter's output into another Cutter's input.
• A deformed drawing cannot be cut, but a cut drawing can be deformed. Make sure to apply cutters before deforming drawings.

Using Game Bones in game assets for Rigged Animation export

Game Bones are the only deformer type in Harmony that can be exported without baking. 

The following properties apply to Harmony Game Bones:

• Can be exported to the game engine in XML format.
• Can be set up and animated just like the regular Bone deformer.
• Can be used with a Kinematic Output node.

Rigging guidelines for Rigged Animation Export game assets

When rigging for RA export, keep in mind that some nodes are not supported by the exporter. As a result, the node structure would not be interpreted well by game engines. It is therefore recommended that you avoid using complex node structures like you may find in Harmony production rigs.

The following is a list of general guidelines to keep in mind if you plan to extract the game data:

Item:	Guideline:
Naming	If you have a top-level Group A, which has a child group inside it (Group B), and a drawing layer is inside of Group B, then the drawing layer is exported as A_B_DrawingLayer. The Unity game engine does not support Unicode characters, it is recommended to avoid using it in scenes intended for games.
Drawing tools	You can use any of the drawing tools you want: Pencil and Brush tools, textured lines, solid fills, and gradients.
Pegs	All peg paths should be set to ‘Separate’. You can change this to default  in the Preferences window.
Peg hierarchy	Attach drawings to pegs and connect those pegs to other pegs to form hierarchies. Connect all pegs to a single Master Peg at the top of your Node view.
Pivots	Use the Advanced Animation Rotationtool to set pivots on pegs. Drawing pivots are not recommended.
Composites	Drawings should be connected to composites to determine the order of drawings shown on-screen.
Z-space	It is best to set this up on the game engine side.
3D-space	Don’t use 3D space in Harmony. Rather set it up in your game engine.
Game Engine layers	Each game asset should exist in its own scene with its animations.
Cutters	See Using cutters in game assets for Rigged Animation export above.
Game Bone Deformations	See Using Game Bones in game assets for Rigged Animation export above.
Export position	Be mindful of where you put your character before exporting. The master pivot of your exported game object will be the center of your Harmony scene (0,0).
Display	Be sure to have a Display at the bottom of your hierarchy.
Scene Markers	Use scene markers to separate animations and skins. For more information on skinning, see Scene Marker View & Marker List and What gaming animation workflows exist in Harmony?
Metadata Notes	You may want to make notes about the scene or specific parts of the character/prop for the programmer. These embedded notes will be exported with your assets to Unity. See Creating Metadata Notes for more information.