# Texture compression formats in GEM RTS

This table provides detailed descriptions and features of each texture compression format supported in GEM RTS, including their applications, advantages, and disadvantages.

| Format          | Description                                                                                                                                  | Features                                                                                                                                          |
| --------------- | -------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| BC1 (DXT1)      | Full-color images without alpha. Used for general textures without transparency.                                                             | Pros: Most compact size. \<br> Cons: Low quality on specific images.                                                                              |
| BC1a (DXT1a)    | Full-color images with 1-bit alpha. Used for textures with minimal transparency, such as small details or effects.                           | -                                                                                                                                                 |
| BC2 (DXT3)      | Full-color images with sharply changing alpha channel. Rarely used due to compatibility limitations.                                         | Cons: Not recommended for use in the current engine version.                                                                                      |
| BC3 (DXT5)      | Full-color images with smooth alpha transitions. Ideal for textures of grass or foliage.                                                     | -                                                                                                                                                 |
| BC4 (ATI1)      | Single-channel textures, such as alpha only or roughness only.                                                                               | Pros: Optimized for high-quality compression of single-channel textures.                                                                          |
| BC5 (3Dc, ATI2) | Two-channel textures, such as normal maps. Particularly useful for textures containing two different data types, such as normals and height. | <p>Pros: Optimized for two-channel textures. <br>Note: Use <code>dds\_bc5\_fix \<path></code> to correct channel errors.</p>                      |
| BC6             | Used for HDR textures, such as sky or lighting textures.                                                                                     | Pros: Ideal for HDR textures.                                                                                                                     |
| BC7             | High-quality full-color images with and without alpha, as well as composite textures with separate information in each channel.              | <p>Pros: Provides significantly better image quality post-compression than BC1.<br>Cons: Larger in size and much slower to compress than BC1.</p> |

{% hint style="info" %}
When you find a texture with incorrectly swapped R and G channels in the normal map, run the console command `dds_bc5_fix <path>`, where `<path>` is the full path to the folder containing all .dds files with BC5 or ATI2 compression that need correction. This command does not degrade the compression quality, as it swaps the channels directly in the binary file.
{% endhint %}


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