/// <summary>
/// Removes a blob from the GLB at the given BufferView
/// Updates accessors and images to have correct new bufferview index
/// This function can invalidate BufferViewId's returned by previous function
/// </summary>
/// <param name="glb">The glb to remove from</param>
/// <param name="bufferViewId">The buffer to remove</param>
public static void RemoveBinaryData(GLBObject glb, BufferViewId bufferViewId)
{
if (glb == null)
{
throw new ArgumentNullException(nameof(glb));
}
if (bufferViewId == null)
{
throw new ArgumentNullException(nameof(bufferViewId));
}
BufferView bufferViewToRemove = bufferViewId.Value;
int id = bufferViewId.Id;
if (bufferViewToRemove.ByteOffset + bufferViewToRemove.ByteLength == glb.BinaryChunkInfo.Length)
{
uint bufferViewLengthAsUint = bufferViewToRemove.ByteLength;
glb.SetFileLength(glb.Header.FileLength - bufferViewLengthAsUint);
glb.SetBinaryChunkLength(glb.BinaryChunkInfo.Length - bufferViewLengthAsUint);
if (glb.BinaryChunkInfo.Length == 0)
{
glb.Root.Buffers.RemoveAt(0);
foreach (BufferView bufferView in glb.Root.BufferViews) // other buffers may still exist, and their index has now changed
{
--bufferView.Buffer.Id;
}
glb.SetFileLength(glb.Header.FileLength - GLTFParser.CHUNK_HEADER_SIZE);
}
else
{
glb.Root.Buffers[0].ByteLength = glb.BinaryChunkInfo.Length;
// write binary chunk header
WriteChunkHeader(glb.Stream, glb.BinaryChunkInfo);
}
// trim the end
glb.Stream.SetLength(glb.Header.FileLength);
// write glb header
WriteHeader(glb.Stream, glb.Header, glb.StreamStartPosition);
}
glb.Root.BufferViews.RemoveAt(id);
if (glb.Root.Accessors != null)
{
foreach (Accessor accessor in glb.Root.Accessors) // shift over all accessors
{
if (accessor.BufferView != null && accessor.BufferView.Id >= id)
{
--accessor.BufferView.Id;
}
if (accessor.Sparse != null)
{
if (accessor.Sparse.Indices?.BufferView.Id >= id)
{
--accessor.Sparse.Indices.BufferView.Id;
}
if (accessor.Sparse.Values?.BufferView.Id >= id)
{
--accessor.Sparse.Values.BufferView.Id;
}
}
}
}
if (glb.Root.Images != null)
{
foreach (GLTFImage image in glb.Root.Images)
{
if (image.BufferView != null && image.BufferView.Id >= id)
{
--image.BufferView.Id;
}
}
}
}
private static BufferViewId _AddBinaryData(GLBObject glb, Stream binaryData, bool createBufferView, long streamStartPosition, string bufferViewName = null)
{
binaryData.Position = streamStartPosition;
// Append new binary chunk to end
uint blobLengthAsUInt = CalculateAlignment((uint)(binaryData.Length - streamStartPosition), 4);
uint newBinaryBufferSize = glb.BinaryChunkInfo.Length + blobLengthAsUInt;
uint newGLBSize = glb.Header.FileLength + blobLengthAsUInt;
uint blobWritePosition = glb.Header.FileLength;
// there was an existing file that had no binary chunk info previously
if (glb.BinaryChunkInfo.Length == 0)
{
newGLBSize += GLTFParser.CHUNK_HEADER_SIZE;
blobWritePosition += GLTFParser.CHUNK_HEADER_SIZE;
glb.SetBinaryChunkStartPosition(glb.Header.FileLength); // if 0, then appends chunk info at the end
}
glb.Stream.SetLength(glb.Header.FileLength + blobLengthAsUInt);
glb.Stream.Position = blobWritePosition; // assuming the end of the file is the end of the binary chunk
binaryData.CopyTo(glb.Stream); // make sure this doesn't supersize it
glb.SetFileLength(newGLBSize);
glb.SetBinaryChunkLength(newBinaryBufferSize);
// write glb header past magic number
WriteHeader(glb.Stream, glb.Header, glb.StreamStartPosition);
WriteChunkHeader(glb.Stream, glb.BinaryChunkInfo);
if (createBufferView)
{
// Add a new BufferView to the GLTFRoot
BufferView bufferView = new BufferView
{
Buffer = new BufferId
{
Id = 0,
Root = glb.Root
},
ByteLength = blobLengthAsUInt, // figure out whether glb size is wrong or if documentation is unclear
ByteOffset = glb.BinaryChunkInfo.Length - blobLengthAsUInt,
Name = bufferViewName
};
if (glb.Root.BufferViews == null)
{
glb.Root.BufferViews = new List <BufferView>();
}
glb.Root.BufferViews.Add(bufferView);
return(new BufferViewId
{
Id = glb.Root.BufferViews.Count - 1,
Root = glb.Root
});
}
return(null);
}
