How to create art and gameplay with 2D tilemaps

Tilemaps can help save time on art creation, as well as memory and CPU usage. This is because tiles can be rendered by a dedicated renderer, and the tiles not visible on the screen can be disabled. A brush tool makes it efficient to paint tiles on a grid, and they can be scripted to use painting rules. They also come with automatic collision generation for more efficient testing and editing.

When authoring tilesheets, it’s important to avoid combining layered tilemaps when they’re not needed, as this helps reduce overdraw. In Happy Harvest, all the tilemaps live under the Grid GameObject. You can see how the tilemap called GroundBase contains all the ground artwork. All these tiles are batched at the same time by setting the rendering Mode to Chunk in the Tilemap Renderer. This can help optimize performance.

The cobblestone path in the sample could have been created with layers of tile artwork: One for the cobblestone and one for the grass. This might sound convenient from an art creation perspective, but it would be less performant due to the layers of overlapping pixels. Only create separate tilemaps when needed, like instances where you need distinct depth planes.

To get a comprehensive introduction to how the Unity Tilemap system works, download the e-book 2D game art, animation, and lighting for artists. 

Some of the tilemaps under the Grid GameObject include:

• UnderwaterTiles: These are used for underwater tiles, for the cliff, and as green ground for the pond area.
• Water: These tiles use a different shader than the others called Sprite-Lit-Material, which is made in Shader Graph to simulate water animation.
• GroundBase: This is the ground artwork comprising tiles for the paths, grass, mud, and stone to fill the gaps from the elevation tiles.
• ObjectsInTiles: This is used for GameObjects painted in a tilemap with the GameObject Brush from the Tile Palette, like the fences.
• TilledTilemap: These tiles are used in the code to detect tiles where seeds can be planted.
• WateredTileLayer: This is used by the game logic to make the tiles look wet. When the tiles dry, the “wet” tiles are removed.
• Warehouse, House: These tilemaps are used to create the warehouse and house. Creating the buildings with tilemaps gave the artist the flexibility to reshape and resize them more efficiently, and save on texture space since parts of the building use the same texture. 
• Crop: This groups all the plants under one GameObject and is also used by the Terrain Manager.

This MonoBehaviour class creates two generic classes called GroundData and CropData. They include gameplay-related variables, like the length of time the tiles appear wet, how fast a plant grows, or how long it lasts without harvesting before it dies.

The Terrain Manager script references the tilemaps and tiles that are used for gameplay purposes, including: 

• Ground Tilemap: This references the tilemap containing soil tiles that indicate where the player can dig and plant seeds. If you dig in any tile outside of this tilemap, nothing will happen.
• Crop Tilemap: This references the Tilemap GameObject that’s the crops’ parent object. Using the Tilemap API here enables you to place, update, and remove crop tiles.
• Water Tilemap: Use this to paint over the tilled soil tiles with simulated water, visually communicating to the player that these tiles are ready for planting and growing.
• Watered tile: This is a rule override tile with the water graphic, which enables you to create tiles with variations of a Rule Tile without setting new rules.
• Tillable tile: This is used to identify tiles that the player can use for digging.
• Tiled tile: This is the Rule Tile used to paint the visual for the tilled soil.

The Terrain Manager script includes functions that use the Tilemap API to read tile information in a Vector3int location format and update the tiles accordingly. Those functions are called from the different tools when the PlayerController triggers the function on them.