Tilemaps and tile-based backgrounds

What is a tilemap?

• Tilemaps are images that are split into constant-size tiles
  • They’re used often for creating loads of background art in 2D games
• A good introduction to Unity tilemaps:
  • Brackeys video: Tilemaps
• See this free asset pack for example!

Tilemap asset

• Manual: Tilemap workflow
• To create a new tilemap, add an image into your project that contains a tilemap
• Change its settings in inspector (see image)
  • Set Sprite mode to Multiple
  • Set Pixels per unit to grid size (e.g., 32)
• Open Sprite Editor and click Slice
  • Set Type to Grid by cell size, click Slice
  • Close the Sprite editor and save.
• Now the sprite asset should have the individual tiles visible like this:
  • 

Tilemap & Grid GameObjects

• Create a new Tilemap GameObject: 2D Object > Tilemap > Rectangular
  • We will draw the levels to the TileMap GameObject
• A Grid GameObject gets creates as the parent object of the tilemap
  • It defines the level-wide grid
  • We usually only need one Grid GameObject per scene
• For multiple layers, you can create multiple tilemaps under the same grid
  • It’s a good idea to have at least two layers:
  • “Terrain tiles” for traversable background
  • “Wall tiles” for collidable walls
• Tilemap GameObject has two components
  • Tilemap Component, Manual: Tilemap
  • Tilemap Renderer Component, Manual: Tilemap renderer

Creating a Tile Palette

• First off, create a new folder for the tile assets (e.g. Assets/Tiles) we’ll create shortly
• We need a new window, Tile Palette, to pick the tiles we draw on the tilemap
  • Window > 2D > Tile Palette
• By default, it does not contain any tiles (a.k.a., a palette) to choose from.
  • Click Create new palette
• Choose a name that describes the tile palette (Like GroundTilePalette), and click Create. Save the palette asset to the tile assets folder we created

  • The tile palette is a prefab asset that we don’t need to touch

    

Drawing with the tile palette

• Now that we have a palette, we can drag the tilemap sprite asset from the Project window to the Tile Palette window.
• This creates tile assets for all tiles: Manual: Tile Assets
  • Choose the folder we created earlier Assets/Tiles to save the assets into
• Then, paint away to create your tile-based level! The brush tool should be active by default.
• Note: We can also drag regular single sprites into the tile palette!

Tile palette pro tips

• Use the Pick or marquee select tool (Eyedropper) to quickly copy-paste areas in the tilemap.
• Hold CTRL when Eraser is selected to make the eraser bigger.
• There are also hidden flip & rotate tools!
  • Go to Preferences > 2D > Tile Palette
  • Select a tool in the list and press the + Button.
    • FlipXTool, FlipYTool, RotateClockwiseTool, RotateCounterClockwiseTool
  • The tools are a bit counterintuitive, but they’re easier to use with hotkeys
    • On Finnish keyboard:
      • Rotate: `, Å
      • Flip: SHIFT +`, SHIFT + Å,)

Collision

• To add collision to your tilemap layer, just add the Tilemap Collider 2D component
• Shape of the collider is decided automatically by Unity for every tile
  • Enter play mode once to see how the collider is shaped
  • You can change tile collider for every tile:
    • Open the Sprite settings and go to Sprite editor > Custom Physics Shape
    • Click on a tile that had bad collision shape and click Generate
• Note: If you want to only have square grid collisions, you can also just use a separate invisible layer for collisions (disable its Tilemap Renderer component)

2D Tilemap Extras

• Packages: 2D Tilemap Extras
• 2D Tilemap Extras Package contains many goodies
  • Autotiling
  • Animated tiles
  • GameObject tiles…
• Comes in 2D projects by default nowadays <!–
  • It’s in the Unity Package Manager as a Preview package
  • Cogwheel > Advanced Project Settings > Enable Preview Packages
  • Packages dropdown: Unity Registry –>

2D extras: Autotiling

• Autotiling is a technique for creating 2d levels faster with Rule tiles
  • E.g., instead of inserting every corner tile by hand, autotiling inserts corner tiles where they should appear
• How To Use Auto Tiling in Unity 2020 (might be outdated in some aspects)
• Open Project Window and right click, then choose Create > 2D > Tiles > Rule Tile
  • Drag a sprite to Inspector
  • Add Tiling Rules (see next slide)
  • Then, Drag the Rule Tile to an empty slot in the tile palette. You’re done!

2D extras: Animated tile

• Use the Animated Tile to create tiles with animations in them.
  • Great for waterfalls, animated torches etc. in the background
  • Create > 2D > Tiles > Animated Tile
  • Drag sprites to the tile in the Inspector
  • Set animation speed (if you want the speed to always be the same, set the minimum and maximum speed to a same value)
  • Drag the newly created animated tile from Project window to Tile Palette
    • Now you can draw with the animated tile!

2D extras: GameObject tile

• GameObjects can be “drawn” (created) as tiles in the tilemap with the GameObject brush
• It’s a different brush than the default brush we’ve been using and has to be set up first
• Remember to go back to default brush when you want to draw background tiles again!
• You’ll need a Prefab of the GameObject you want to spawn in the tilemap

GameObject tile setup

1. In Tile palette, choose the brush tool
2. Change Default brush to GameObject brush
3. Drag the GameObject Prefab to Element 0
4. Click Edit to enter the edit mode
5. Click on the tile you added the sprite to
6. Click Edit to exit Edit mode.
   • Now, when you click on the chosen tile, it should display the GameObject in Element 0.
7. Use the GameObject brush to add new GameObjects - they’ll show up in Hierarchy right away.

Exercise 1. A tiled level

Import a tilemap from an existing sprite sheet. Create a tiny level out of your tile assets!

GameObject on a grid

• Note: If snapping to the grid is your concern, you’re better off using the GameObject tile
• Without the GameObject tile, you can do it like this:
• To snap a player character to a grid, you have two options: a) Move the grid to position (0.5, 0.5) b) Make the player’s sprite renderer a child GameObject, and move it to coordinates (0.5,-0.5,0)
  • Also, add the same offset to player’s RigidBody
• Then, click on the Snap to grid button (left side of Play button)

Fixing ugly seams in tilemap

• Many things can cause this.
• In Game Mode, create a new resolution and set it to a Fixed resolution that is a multiple of your tile size
  • For example, for a tile size of 32, a 480x320 is a good choice.
• Edit > Project Settings > Quality > Anti-aliasing: Disabled
  • See also 2D animation: Pixel art in unity
• You might even have to create a custom material for all pixelart sprites that has Pixel snap enabled