MonoGame tooling build for basis_universal
This tool can be used to compress an image into various texture compression formats. Examples are BC1-7, PVRTC, ETC1, ETC2, ASTC and ATC.
To use we must first create a "basis" file, this is an intermediate file containing the image data. From this file ALL over texture formats can be created. It is probably worth caching this "basis" file between builds.
basisu -file foo.png -ktx2
Adding a -uastc might give better results for some compression types.
Once you have the "basis" file you can then transform that into specific formats
by using the -unpack command. Providing the -format_only flag will produce
ONLY that format. Omitting this flag will result in ALL supported formats being
produced.
The values for -format_only are the numerical values for the transcoder_texture_format. For example ATC with an Alpha channel maps to cTFATC_RGBA which has a numerical value of 12.
basisu -unpack foo.ktx2 -ktx_only -linear -format_only 2
The output file(s) are listed in the output. There may be many output files. They will be stored in a .ktx files, but the internal image data will be compressed. We can use libraries like libktxsharp to read the .ktx data.
byte[] ktxBytes = File.ReadAllBytes("myImage.ktx");
KtxStructure ktxStructure = null;
using (MemoryStream ms = new MemoryStream(ktxBytes))
{
ktxStructure = KtxLoader.LoadInput(ms);
}
Console.WriteLine(ktxStructure.header.pixelWidth);