2D Textures

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.

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. Note that this flattening happens internally to Unity, and is optional, so you can continue to save and import your PSD files with layers intact. The PSD file is not flattened, in other words.

Properties

The Texture Inspector looks a bit different from most others:

The inspector is split into two sections, the Texture Importer and the texture preview.

Texture Importer

Textures all come from image files in your Project Folder. How they are imported is specified by the Texture Importer. You change these by selecting the file texture in the Project View and modifying the Texture Importer in the Inspector.

The topmost item in the inspector is the Texture Type menu that allows you to select the type of texture you want to create from the source image file.

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 foliage. The Light page has more info on all this, but the main thing is that for textures to be usable for cookies you just need to set the Texture Type to Cookie.

Per-Platform Overrides

When you are building for different platforms, you have to think about the resolution of your textures for the target platform, the size and the quality. You can set default options and then override the defaults for a specific platform.

If you have set the Texture Type to Advanced then the Texture Format has different values.

ios

Android

Unless you’re targeting a specific hardware, like Tegra, we’d recommend using ETC1 compression. If needed you could store an external alpha channel and still benefit from lower texture footprint. If you absolutely want to store an alpha channel in a texture, RGBA16 bit is the compression supported by all hardware vendors.

Textures can be imported from DDS files but only DXT or uncompressed pixel formats are currently supported.

If your app utilizes an unsupported texture compression, the textures will be uncompressed to RGBA 32 and stored in memory along with the compressed ones. So in this case you lose time decompressing textures and lose memory storing them twice. It may also have a very negative impact on rendering performance.

Flash

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, 2048 etc. pixels. The textures do not have to be square, i.e. width can be different from height. Note that each platform may impose maximum texture sizes.

It is possible to use other (non power of two - “NPOT”) texture sizes with Unity. Non power of two texture sizes generally take slightly more memory and might be slower to read by the GPU, so for performance it’s best to use power of two sizes whenever you can. If the platform or GPU does not support NPOT texture sizes, then Unity will scale and pad the texture up to next power of two size, which will use even more memory and make loading slower (in practice, this always happens on Flash and some older Android devices). In general you’d want to use non power of two sizes only for GUI purposes.

Non power of two texture assets can be scaled up at import time using the Non Power of 2 option in the advanced texture type in the import settings.

UV Mapping

When mapping a 2D texture onto 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 normal & 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 use mipmaps for in-game textures; the only exceptions are textures that will never be minified (e.g. GUI textures).

Normal Maps

Normal maps are used by normal 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 make a terrain, you normally use your main texture to show where there are areas of grass, rocks sand, etc… If your terrain has a decent size, it will end up very blurry. Detail textures hide this fact by fading in small details as your main texture gets 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.

Reflections (Cube Maps)

If you want to use texture for reflection maps (e.g. use the Reflective built-in 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.