Unreal UIs and Texture Sizes

Unreal gives the user a huge number of texture options. Some of which, as user interface designers, we are unlikely to use but are still worth knowing about.

Here we’ll cover some of the texture-related issues that you might encounter as a UI programmer in Unreal.

Texture Sizes

The size of the texture affects its compression and mipmap generation support.

Compression

Generally UI textures are not compressed, as DXT5 compression in particular can cause some artifacts that can ruin the clean lines of some UI styles. However depending on your need to reduce your memory footprint (and whether your UIs aesthetic is compatible with it), you may want to enable compression.

DXT5 compression is only available for textures that are a multiple of 4. This is important to know, even if you are not planning on enabling compression for your UI textures as you may need to change your mind in the future.

Mipmap Generation

Mipmap scaling are not commonly used in UIs. But for some assets that could be shown at many different scales, like icons used in many parts of the UI, mipmap support may be useful.

Mipmap generation is only possible for textures that are a power of two.

If the texture is not a power-of-two and not a multiple of 4, both compression and mipmap generation are disabled. The "Format" is a simple 32-bit image, B8G8R8A8.
▲ If the texture is not a power-of-two and not a multiple of 4, both compression and mipmap generation are disabled. The "Format" is a simple 32-bit image, B8G8R8A8.
If the texture is a multiple of 4 then it can be compressed with DXT5 compression. However mipmaps are not supported.
▲ If the texture is a multiple of 4 then it can be compressed with DXT5 compression. However mipmaps are not supported.
Power-of-two textures are supported by both
compression and mipmap generation.
▲ Power-of-two textures are supported by both compression and mipmap generation.

Disabling Texture Compression

▲ With texture compression manually disabled for our 256px texture, the resource size increases from 85Kb to 341Kb.

Summary

Texture Size Compression Mipmaps
Power-of-two DXT5 Supported Supported
Multiple of 4 DXT5 Supported Unsupported
**Other Unsupported Unsupported