A Go package to write data to VTK XML files.
Note: not all feature are implemented yet. Basic VTK XML files and ParaViewData (PVD) collections are availabe.
The package supports a variety of VTK XML styles to be written,
i.e. image data (.vti), rectilinear grids (.vtr), structured grids (.vts), and unstructured grids (*.vtu).
Each format allows to write the XML using ascii, base64, or binary encoding. The
data can be compressed using zlib by means of the Go standard library compress/zlib.
Four different formats are supported by their constructor:
Image()for.vtifilesRectilinear()for.vtrfilesStructured()for.vtsfilesUnstructured()for.vtufiles
These support three types of encoding: Ascii(),
Base64(), and Raw() (binary data). The latter two result
in significantly smaller files. Note, Base64() does maintain
valid XML, while Raw() does not.
Additionally, Base64() and Raw() encoding allow
to compress the data before encoding by passing Compressed(),
to further reduces file size.
Data is added by Add(). Point/Cell data can be inserted as
Add(Data("fieldname", data)), which infers if the data should
be place on the points or cells. Alternatively, the CellData
and PointData allow to directly write data to either
points or cells. Global, generic data fields can be
added by FieldData.
The file is written to disk by
either Save(filename string) or Write(w io.Writer).
For each file type a small example is presented.
vti, err := govtk.Image(govtk.WholeExtend(0, nx, 0, ny, 0, nz))
data := make([]float64, (nx+1)*(ny+1)*(nz+1))
vti.Add(govtk.Data("fieldname", data))
vti.Save("image.vti") vtr, err := govtk.Rectilinear(govtk.WholeExtend(0, nx, 0, ny, 0, nz))
// store x, y, z coordinates a 1D vectors
x := make([]float64, nx+1)
y := make([]float64, ny+1)
z := make([]float64, nz+1)
// fill x, y, z accordingly
// ...
// store coordinates
vtr.Add(govtk.Points(x, y, z))
vtr.Add(govtk.Data(...))
vtr.Save("rectilinear.vtr") vts, err := govtk.Structured(govtk.WholeExtend(0, nx, 0, ny, 0, nz))
// store all x,y,z tuples for each node
xyz := make([]float64, 3*(nx+1)*(ny+1)*(nz+1))
// fill xyz with each coordinate
// ...
vts.Add(govtk.Points(xyz))
vts.Add(govtk.Data(...))
vts.Save("structured.vts") vtu, err := govtk.Unstructured()
// store all x,y,z tuples for each node
vtu.Add(Points(...))
// provide cell connectivity, e.g. two tet elements
conn := []int{0, 1, 2, 3, 0, 4, 5, 6}
offset := []int{0, 4, 6} // start of each element in conn
labels := []int{20, 20} // VTK labels
vtu.Add(govtk.Cells(conn, offset, labels))
// store data and save
vtu.Add(govtk.Data(...))
vtk.Save("unstructured.vtu" The package also allows to write PVD collections. These
ParaviewData
files allow to store references to multiple VTK XML files,
which might be located anywhere on disk. Each file can save a
time step, part id, and group name as attribute. The time steps
are directly available in ParaView, which is beneficial for data of
transient time series.
For example to store a time series:
pvd, err := govtk.NewPVD(govtk.Directory("./mypvd"))
// some time series
for t := 0; t < 100; t++ {
// generate output data
vti, err := govtk.Image(govtk.WholeExtend(0, nx, 0, ny, 0, nz), govkt.Raw())
vti.Add(govtk.Data(...))
// attach to PVD collection
pvd.Add(vti, govtk.Time(float64(t))
}
// save PVD main file
pvd.Save(filepath.Join(pvd.Dir(), "pvd.pvd"))Provides the following directory
myvpd/
file_000.vti
file_001.vti
...
file_099.vti
pvd.pvd
Not yet supported
Basic encoding and compression is controlled by:
govtk.Ascii() // plain ascii
govtk.Binary() // base64 encoding
govtk.Raw() // plain binary
// compression only applies to `govtk.Binary()` and `govtk.Raw()`
govtk.Compressed() // applies govtk.DefaultCompression
govtk.CompressedLevel(level int) // applies received compression level
// compression levels are directly taken from `compress/zlib`
const (
govtk.NoCompression = zlib.NoCompression
govtk.BestSpeed = zlib.BestSpeed
govtk.BestCompression = zlib.BestCompression
govtk.DefaultCompression = zlib.DefaultCompression
govtk.HuffmanOnly = zlib.HuffmanOnly
) to be implemented
Install the package
go get -u -v github.com/maxvdkolk/govtk/...