public static void WritePAA(BinaryWriterEx writer, ReadOnlyMemory2D <ColorRgba32> image, ColorRgba32 max, ColorRgba32 avg, PAAType type = PAAType.DXT5, PAAFlags flags = PAAFlags.InterpolatedAlpha)
{
if (type != PAAType.DXT5 && type != PAAType.DXT1)
{
throw new NotSupportedException();
}
var enc = new BCnEncoder.Encoder.BcEncoder(type == PAAType.DXT5 ? CompressionFormat.Bc3 : CompressionFormat.Bc1);
var mipmaps = new List <MipmapEncoder>();
var width = image.Width;
var height = image.Width;
var offset = type == PAAType.DXT5 ? 128 : 112;
foreach (var mipmap in enc.EncodeToRawBytes(image))
{
if (width > 2 || height > 2)
{
var menc = new MipmapEncoder(mipmap, width, height, offset);
offset += menc.MipmapEntrySize;
mipmaps.Add(menc);
width = width / 2;
height = height / 2;
}
}
writer.Write(type == PAAType.DXT5 ? (ushort)0xff05 : (ushort)0xff01);
writer.WriteAscii("GGATCGVA", 8);
writer.Write((uint)4);
writer.Write(avg.r);
writer.Write(avg.g);
writer.Write(avg.b);
writer.Write(avg.a);
writer.WriteAscii("GGATCXAM", 8);
writer.Write((uint)4);
writer.Write(max.r);
writer.Write(max.g);
writer.Write(max.b);
writer.Write(max.a);
if (type == PAAType.DXT5)
{
writer.WriteAscii("GGATGALF", 8);
writer.Write((uint)4);
writer.Write((uint)flags);
}
writer.WriteAscii("GGATSFFO", 8);
writer.Write(16 * 4);
for (int i = 0; i < 16; ++i)
{
if (i < mipmaps.Count)
{
writer.Write((uint)mipmaps[i].Offset);
}
else
{
writer.Write((uint)0);
}
}
writer.Write((ushort)0x0000);
int index = 0;
foreach (var mipmap in mipmaps)
{
if (writer.Position != mipmap.Offset)
{
throw new Exception($"Wrong offset @{mipmap.Width} : {writer.Position} != { mipmap.Offset}");
}
writer.Write(mipmap.WidthEncoded);
writer.Write(mipmap.Height);
writer.WriteUInt24((uint)mipmap.PaaData.Length);
writer.Write(mipmap.PaaData);
index++;
width = width / 2;
height = height / 2;
}
writer.Write((uint)0x0000);
writer.Write((ushort)0x0000);
}