KTX/KTX2 Support for EEVEE

I tested different image formats in EEVEE and Cycles to compare load speed and VRAM usage.

In Cycles, uncompressed images are used, so all formats consume almost the same amount of VRAM. However, for load speed, PNG was the fastest, while JPG and EXR were the slowest (though in some cases, EXR is inevitable).

EEVEE, on the other hand, can use compressed images like DDS, and the results were interesting. I loaded 256 images at 4096x4096 resolution onto 256 planes using an RTX 4090. VRAM Usage

PNG – 21.8GB
JPG – Over 24GB
EXR – Over 24GB
DDS/DXT1 (No Alpha) – 2.1GB
DDS/DXT5 (With Alpha) – 4.1GB

Additionally, DDS files loaded faster than all other formats.

Tip for EEVEE users: Use DDS, at least for environment and background textures. (You can use GIMP to export DDS files.)

As far as I know, KTX and KTX2 are more OpenGL- and Vulkan-friendly than DDS. KTX is developed by the Khronos Group and is open-source.

The Proposal:

Add KTX format support for EEVEE.