/// <summary>
/// Loads a KTX file from a stream.
/// </summary>
public static KtxFile Load(Stream s)
{
using (BinaryReader br = new BinaryReader(s, UTF8, true))
{
KtxHeader header = br.ReadStruct <KtxHeader>();
if (header.NumberOfArrayElements > 0)
{
throw new NotSupportedException("KTX files with arrays are not supported.");
}
KtxFile ktx = new KtxFile(header);
int keyValuePairBytesRead = 0;
while (keyValuePairBytesRead < header.BytesOfKeyValueData)
{
KtxKeyValuePair kvp = KtxKeyValuePair.ReadKeyValuePair(br, out int read);
keyValuePairBytesRead += read;
ktx.KeyValuePairs.Add(kvp);
}
uint numberOfFaces = Math.Max(1, header.NumberOfFaces);
ktx.MipMaps.Capacity = (int)header.NumberOfMipmapLevels;
for (uint mipLevel = 0; mipLevel < header.NumberOfMipmapLevels; mipLevel++)
{
uint imageSize = br.ReadUInt32();
uint mipWidth = header.PixelWidth / (uint)(Math.Pow(2, mipLevel));
uint mipHeight = header.PixelHeight / (uint)(Math.Pow(2, mipLevel));
ktx.MipMaps.Add(new KtxMipmap(imageSize, mipWidth, mipHeight, numberOfFaces));
bool cubemap = header.NumberOfFaces > 1 && header.NumberOfArrayElements == 0;
for (uint face = 0; face < numberOfFaces; face++)
{
byte[] faceData = br.ReadBytes((int)imageSize);
ktx.MipMaps[(int)mipLevel].Faces[(int)face] = new KtxMipFace(faceData, mipWidth, mipHeight);
if (cubemap)
{
uint cubePadding = 0u;
cubePadding = 3 - ((imageSize + 3) % 4);
br.SkipPadding(cubePadding);
}
}
uint mipPaddingBytes = 3 - ((imageSize + 3) % 4);
br.SkipPadding(mipPaddingBytes);
}
return(ktx);
}
}
/// <summary>
/// Writes this ktx file into a stream.
/// </summary>
public void Write(Stream s)
{
if (MipMaps.Count < 1 || MipMaps[0].NumberOfFaces < 1)
{
throw new InvalidOperationException("The KTX structure should have at least 1 mipmap level and 1 Face before writing to file.");
}
using (BinaryWriter bw = new BinaryWriter(s, UTF8, true))
{
uint bytesOfKeyValueData = (uint)KeyValuePairs.Sum(x => x.GetSizeWithPadding());
Header.BytesOfKeyValueData = bytesOfKeyValueData;
Header.NumberOfFaces = MipMaps[0].NumberOfFaces;
Header.NumberOfMipmapLevels = (uint)MipMaps.Count;
Header.NumberOfArrayElements = 0;
if (!Header.VerifyHeader())
{
throw new InvalidOperationException("Please verify the header validity before writing to file.");
}
bw.WriteStruct(Header);
foreach (KtxKeyValuePair keyValuePair in KeyValuePairs)
{
KtxKeyValuePair.WriteKeyValuePair(bw, keyValuePair);
}
for (int mip = 0; mip < Header.NumberOfMipmapLevels; mip++)
{
uint imageSize = MipMaps[mip].SizeInBytes;
bw.Write(imageSize);
bool isCubemap = Header.NumberOfFaces == 6 && Header.NumberOfArrayElements == 0;
for (int f = 0; f < Header.NumberOfFaces; f++)
{
bw.Write(MipMaps[mip].Faces[f].Data);
uint cubePadding = 0u;
if (isCubemap)
{
cubePadding = 3 - ((imageSize + 3) % 4);
}
bw.AddPadding(cubePadding);
}
uint mipPaddingBytes = 3 - ((imageSize + 3) % 4);
bw.AddPadding(mipPaddingBytes);
}
}
}
public static uint WriteKeyValuePair(BinaryWriter bw, KtxKeyValuePair pair)
{
int keySpanLength = UTF8.GetByteCount(pair.Key);
Span <byte> keySpan = stackalloc byte[keySpanLength];
Span <byte> valueSpan = pair.Value;
uint totalSize = (uint)(keySpan.Length + 1 + valueSpan.Length);
int paddingBytes = (int)(3 - ((totalSize + 3) % 4));
bw.Write(totalSize);
bw.Write(keySpan);
bw.Write((byte)0);
bw.Write(valueSpan);
return((uint)(totalSize + paddingBytes));
}
