private static byte[] TryLoadBase64BinaryBufferUnchecked(Schema.Buffer buffer, string prefix)
{
if (buffer.Uri is null || !buffer.Uri.StartsWith(prefix, StringComparison.OrdinalIgnoreCase))
{
return(null);
}
string content = buffer.Uri.Substring(prefix.Length);
return(Convert.FromBase64String(content));
}
/// <summary>
/// Gets a binary buffer referenced by a specific <code>Schema.Buffer</code>
/// </summary>
/// <param name="model">The <code>Schema.Gltf</code> model containing the <code>Schema.Buffer</code></param>
/// <param name="bufferIndex">The index of the buffer</param>
/// <param name="externalReferenceSolver">An user provided lambda function to resolve external assets</param>
/// <returns>Byte array of the buffer</returns>
/// <remarks>
/// Binary buffers can be stored in three different ways:
/// - As stand alone files.
/// - As a binary chunk within a glb file.
/// - Encoded to Base64 within the JSON.
///
/// The external reference solver funcion is called when the buffer is stored in an external file,
/// or when the buffer is in the glb binary chunk, in which case, the Argument of the function will be Null.
///
/// The Lambda function must return the byte array of the requested file or buffer.
/// </remarks>
public static byte[] LoadBinaryBuffer(this Gltf model, int bufferIndex, Func <string, byte[]> externalReferenceSolver)
{
Schema.Buffer buffer = model.Buffers[bufferIndex];
byte[] bufferData = LoadBinaryBufferUnchecked(buffer, externalReferenceSolver);
// As per https://github.com/KhronosGroup/glTF/issues/1026
// Due to buffer padding, buffer length can be equal or larger than expected length by only 3 bytes
if (bufferData.Length < buffer.ByteLength || (bufferData.Length - buffer.ByteLength) > 3)
{
throw new InvalidDataException($"The buffer length is {bufferData.Length}, expected {buffer.ByteLength}");
}
return(bufferData);
}
private static byte[] LoadBinaryBufferUnchecked(Schema.Buffer buffer, Func <string, byte[]> externalReferenceSolver)
{
return(TryLoadBase64BinaryBufferUnchecked(buffer, EMBEDDEDGLTFBUFFER)
?? TryLoadBase64BinaryBufferUnchecked(buffer, EMBEDDEDOCTETSTREAM)
?? externalReferenceSolver(buffer?.Uri));
}
internal byte[] LoadDataUri(Schema.Buffer buff)
{
int idxComa = buff.Uri.IndexOf(",", 5, StringComparison.Ordinal);
return(Convert.FromBase64String(buff.Uri.Substring(idxComa + 1)));
}
