License: Donated by Norbert Nopper for glTF testing.

https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/Cube

Converted .png to .ktx image by Syoyo Fujita.

.png -> .ppm using image magic(resize with 25% to reduce file size) .ppm -> .ktx using toktx in KTX-Software https://github.com/KhronosGroup/KTX-Software