Texture 2D

Textures bring your Meshes, Particles, and interfaces to life! They are image or movie files that you lay over or wrap around your objects. As they are so important, they have a lot of properties. If reading this for the first time, jump down to Details, and return to the actual settings when you need a reference.

The shaders you use for your objects put specific requirements on which textures you need, but the basic principle is that you can put any image file inside your project. If it meets the size requirements (specified below), it will get imported and optimized for game use. This extends to multi-layer Photoshop or TIFF files - they are flattened on import, so there is no size penalty for your game.

Properties

The Texture Inspector looks a bit different from most others:

The top section contains a few settings, and the bottom part contains a texture preview. The changes you make to the bottom part only affect the display, and not the texture itself.

Import Settings

Textures all come from image files in your Project Folder. How they are imported is specified by the texture's Import Settings. You change these by selecting the file texture in the Project View and clicking the Import Settings button on the toolbar above:

The Import Settings Button

This brings up the import settings dialog:

The Texture Import Settings dialog

Details

Supported Formats

Unity can read the following file formats: PSD, TIFF, JPG, TGA, PNG, GIF, BMP, IFF, PICT. It should be noted that Unity can import multi-layer PSD & TIFF files just fine. They are flattened automatically on import but the layers are maintained in the assets themselves, so you don't lose any of your work when using these file types natively. This is important as it allows you to just have one copy of your textures that you can use from Photoshop, through your 3D modelling app and into Unity.

Texture Sizes

Ideally texture sizes should be powers of two on the sides. These sizes are as follows: 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024 or 2048 pixels. The textures do not have to be square, i.e. width can be different from height.

It is possible to use other (non power of two) texture sizes with Unity. Non power of two texture sizes work best when used on GUI Textures, however if used on anything else they will be converted to an uncompressed RGBA 32 bit format. That means they will take up more video memory (compared to DXT compressed textures) and will be slightly slower to load. In general you'll use non power of two sizes only for making GUI.

Non power of two texture assets can be scaled up at import time using a Scale NonPower2 Sizes Up option in the import settings. Then Unity will scale texture contents up to the next power of two, and in the game they will behave just like any other texture. So they can still be compressed and very fast to load.

UV Mapping

When mapping a 2D texture on to a 3D model, some sort of wrapping is done. This is called UV mapping and is done in your 3D modelling app. Inside Unity, you can scale and move the texture using Materials. Scaling bump & detail maps is especially useful.

Mip Maps

Mip Maps are a list of progressively smaller versions of an image, used to optimise performance on real-time 3D engines. Objects that are far away from the camera use the smaller texture versions. Using mip maps uses 33% more memory, but not using them can be a huge performance loss. You should always you mipmaps for in-game textures; the only exceptions are textures that will never be minified (e.g. GUI textures).

Bump Maps

Bump maps are used by bump map shaders to make low-polygon models look as if they contain more detail. Unity uses normal maps encoded as RGB images. You also have the option to generate a normal map from a grayscale height map image.

Detail Maps

If you want to do a terrain, you normally use your main texture to show where there are grass, rocks sand, etc... If your terrain has a decent size, you will end up with a very blurry terrain. Detail textures hide this fact by fading in small details as your main texture get up close.

When drawing detail textures, a neutral gray is invisible, white makes the main texture twice as bright and black makes the main texture completely black.

Cube Maps

If you want to use texture for reflection maps (e.g. use Reflective builtin shaders), you need to use Cubemap Textures.

Anisotropic filtering

Anisotropic filtering increases texture quality when viewed from a grazing angle, at some expense of rendering cost (the cost is entirely on the graphics card). Increasing anisotropy level is usually a good idea for ground and floor textures. In Quality Settings anisotropic filtering can be forced for all textures or disabled completely.

No anisotropy used on the ground texture

Maximum anisotropy used on the ground texture

Light Cookies

An interesting way to add a lot of visual detail to your scenes is to use Cookies - greyscale textures you use to control the precise look of in-game lighting. This is fantastic for making moving clouds and giving an impression of dense foilage. The Light page has more info on all this, but the main thing is that for textures to be usable for cookies, the following properties need to be set:

For Spotlight Cookies, use the following settings:

You should keep the edges of you cookie texture solid black in order to get the proper effect. In the Texture Inspector, set the Edge Mode to Clamp.

For Directional Lights, use the following settings:

This texture will tile, so in the texture inspector, you must set the Edge Mode to Repeat.

For Point Lights, you need to use Cube Maps. To generate one, either make six textures and assign them as described in Cubemap Textures or generate one with the following settings: