Sprite Packer Modes

To enable or disable the Sprite AtlasA texture that is composed of several smaller textures. Also referred to as a texture atlas, image sprite, sprite sheet or packed texture. More info
See in Glossary default packing behavior, open the Editor settings (menu: Edit > Project Settings > Editor) and navigate to Sprite Packer > Mode . Select the Sprite Packer Mode to determine how Unity uses the Sprite Atlas within the Editor.

• Disabled: SpriteA 2D graphic objects. If you are used to working in 3D, Sprites are essentially just standard textures but there are special techniques for combining and managing sprite textures for efficiency and convenience during development. More info
  See in Glossary Atlas packing is disabled in the Project. Sprite Atlases are not built when the Project enters Play Mode or when a build is published. Pack Preview is also disabled.

• Enabled for Builds (Legacy Sprite Packer): Selecting this mode enables the legacy Sprite PackerA facility that packs graphics from several sprite textures tightly together within a single texture known as an atlas. Unity provides a Sprite Packer utility to automate the process of generating atlases from the individual sprite textures. More info
  See in Glossary and disables the Sprite Atlas, as they cannot be enabled at the same time. Unity packs Sprites with the legacy Sprite Packer for published builds only. The Editor and Play Mode reference the original source Texture instead of the Texture within the packed Atlas.

• Always Enabled (Legacy Sprite Packer): Selecting this mode enables the legacy Sprite Packer and disables the Sprite Atlas, as they cannot be enabled at the same time. Unity packs selected Textures into Atlases with the legacy Sprite Packer, and Sprites reference the packed Textures during run time. However, Sprites will reference the original unpacked Textures during Edit Mode.

• Enabled for Builds: Unity packs Sprites into the Sprite Atlas for published builds only. The Editor and Play Mode reference the original source Texture instead of the Texture within the Sprite Atlas.

• Always Enabled: This option is enabled by default. Unity packs selected Textures into Sprite Atlases, and Sprites reference the packed Textures during run time. However, Sprites will reference the original unpacked Textures during Edit Mode.