ENH: update coding for VTK fileFormats, make open() virtual

- add writer support for VERTICES

- updated use of globalIndex

ENH: add base vtk writer for points/verts/lines

STYLE: noexcept, explicit constructors etc

src/OpenFOAM/db/IOstreams/hashes/base64Layer.C

@@ -55,25 +55,25 @@ std::size_t Foam::base64Layer::encodedLength(std::size_t n)
 
 // * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * * //
 
-inline unsigned char Foam::base64Layer::encode0() const
+inline unsigned char Foam::base64Layer::encode0() const noexcept
 {
     // Top 6 bits of char0
     return base64Chars[((group_[0] & 0xFC) >> 2)];
 }
 
-inline unsigned char Foam::base64Layer::encode1() const
+inline unsigned char Foam::base64Layer::encode1() const noexcept
 {
     // Bottom 2 bits of char0, Top 4 bits of char1
     return base64Chars[((group_[0] & 0x03) << 4) | ((group_[1] & 0xF0) >> 4)];
 }
 
-inline unsigned char Foam::base64Layer::encode2() const
+inline unsigned char Foam::base64Layer::encode2() const noexcept
 {
     // Bottom 4 bits of char1, Top 2 bits of char2
     return base64Chars[((group_[1] & 0x0F) << 2) | ((group_[2] & 0xC0) >> 6)];
 }
 
-inline unsigned char Foam::base64Layer::encode3() const
+inline unsigned char Foam::base64Layer::encode3() const noexcept
 {
     // Bottom 6 bits of char2
     return base64Chars[(group_[2] & 0x3F)];

src/OpenFOAM/db/IOstreams/hashes/base64Layer.H

@@ -39,8 +39,8 @@ SourceFiles
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef base64Layer_H
+#ifndef Foam_base64Layer_H
-#define base64Layer_H
+#define Foam_base64Layer_H
 
 #include <iostream>
 
@@ -72,16 +72,10 @@ class base64Layer
 
     // Private Member Functions
 
-        inline unsigned char encode0() const;
+        inline unsigned char encode0() const noexcept;
-        inline unsigned char encode1() const;
+        inline unsigned char encode1() const noexcept;
-        inline unsigned char encode2() const;
+        inline unsigned char encode2() const noexcept;
-        inline unsigned char encode3() const;
+        inline unsigned char encode3() const noexcept;
-
-        //- No copy construct
-        base64Layer(const base64Layer&) = delete;
-
-        //- No copy assignment
-        void operator=(const base64Layer&) = delete;
 
 
 protected:
@@ -91,6 +85,12 @@ protected:
         //- Add a character to the group, outputting when the group is full.
         void add(char c);
 
+        //- No copy construct
+        base64Layer(const base64Layer&) = delete;
+
+        //- No copy assignment
+        void operator=(const base64Layer&) = delete;
+
 
 public:
 

src/fileFormats/vtk/base/foamVtkCore.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -52,7 +52,7 @@ namespace vtk
   // Enumerations
 
     //- The context when outputting a VTK file (XML or legacy).
-    enum OutputContext
+    enum OutputContext : uint8_t
     {
         INLINE,     //!< Generate header and inline data
         HEADER,     //!< Generate header only
@@ -72,21 +72,21 @@ namespace vtk
         LEGACY_BINARY = 0x22, //!< Legacy raw binary, legacyRawFormatter
     };
 
-    //- Test for XML append format
+    //- Test for vtk append format (xml)
-    inline bool isAppend(enum formatType fmt)
+    inline bool isAppend(enum formatType fmt) noexcept
     {
         return (uint8_t(fmt) & 0x10);
     }
 
     //- Test for vtk legacy format
-    inline bool isLegacy(enum formatType fmt)
+    inline bool isLegacy(enum formatType fmt) noexcept
     {
         return (uint8_t(fmt) & 0x20);
     }
 
 
-    //- Equivalent to enumeration in "vtkCellType.h"
+    //- Equivalent to enumeration in "vtkCellType.h" (should be uint8_t)
-    enum cellType
+    enum cellType : uint8_t
     {
         VTK_EMPTY_CELL       = 0,
         VTK_VERTEX           = 1,
@@ -110,7 +110,7 @@ namespace vtk
 
 
     //- Some common XML tags for vtk files
-    enum class fileTag
+    enum class fileTag : uint8_t
     {
         VTK_FILE,               //!< "VTKFile"
         DATA_ARRAY,             //!< "DataArray"
@@ -140,7 +140,7 @@ namespace vtk
     extern const Foam::Enum<fileTag> fileTagNames;
 
     //- Some common XML attributes for vtk files
-    enum class fileAttr
+    enum class fileAttr : uint8_t
     {
         OFFSET,                 //!< "offset"
         NUMBER_OF_COMPONENTS,   //!< "NumberOfComponents"
@@ -156,7 +156,7 @@ namespace vtk
     extern const Foam::Enum<fileAttr> fileAttrNames;
 
     //- Some common names for XML DataArray entries
-    enum class dataArrayAttr
+    enum class dataArrayAttr : uint8_t
     {
         POINTS,                 //!< "Points"
         OFFSETS,                //!< "offsets"

src/fileFormats/vtk/base/foamVtkPTraits.H

@@ -42,17 +42,17 @@ Description
 namespace Foam
 {
 
-// Forward declarations
+// Forward Declarations
 class endian;
 
 /*---------------------------------------------------------------------------*\
                          Class vtkPTraits Declaration
 \*---------------------------------------------------------------------------*/
 
-template<class PrimitiveType>
+template<class Type>
 struct vtkPTraits
 {
-    // Static data members
+    // Static Data Members
     static const char* const typeName;
 };
 

src/fileFormats/vtk/file/foamVtkFileWriter.C

@@ -290,10 +290,10 @@ Foam::vtk::fileWriter::fileWriter
     const vtk::outputOptions opts
 )
 :
-    contentType_(contentType),
-    opts_(opts),
-    parallel_(false),
     state_(outputState::CLOSED),
+    contentType_(contentType),
+    parallel_(false),
+    opts_(opts),
     nCellData_(0),
     nPointData_(0),
     outputFile_(),
@@ -360,7 +360,7 @@ bool Foam::vtk::fileWriter::open(const fileName& file, bool parallel)
     // This means we can always check if format_ is defined to know if output
     // is desired on any particular process.
 
-    if (Pstream::master() || !parallel_)
+    if (!parallel_ || Pstream::master())
     {
         mkDir(outputFile_.path());
 

src/fileFormats/vtk/file/foamVtkFileWriter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018-2021 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -42,6 +42,8 @@ Description
 
 SourceFiles
     foamVtkFileWriter.C
+    foamVtkFileWriterI.H
+    foamVtkFileWriterTemplates.C
 
 \*---------------------------------------------------------------------------*/
 
@@ -71,7 +73,7 @@ protected:
     // Protected Member Data
 
         //- Internal tracking of the output state.
-        enum outputState
+        enum outputState : uint8_t
         {
             CLOSED = 0,     //!< File is closed
             OPENED,         //!< File is opened
@@ -86,18 +88,18 @@ protected:
         static const Enum<outputState> stateNames;
 
 
-        //- The content type
-        vtk::fileTag contentType_;
-
-        //- The requested output options
-        outputOptions opts_;
-
-        //- Writing in parallel (via master)
-        bool parallel_;
-
         //- The output state
         outputState state_;
 
+        //- The content type (PolyData, UnstructuredGrid ...)
+        vtk::fileTag contentType_;
+
+        //- Parallel writing (via master)
+        bool parallel_;
+
+        //- Requested output options
+        vtk::outputOptions opts_;
+
         //- The number of CellData written for the Piece thus far.
         label nCellData_;
 
@@ -128,7 +130,7 @@ protected:
         //- The backend ostream in use
         inline std::ofstream& os() noexcept;
 
-        //- The VTK formatter in use
+        //- The VTK formatter in use. FatalError for off-processor.
         inline vtk::formatter& format();
 
         //- True if output state corresponds to the test state.
@@ -231,16 +233,16 @@ public:
     // Member Functions
 
         //- The content type
-        inline vtk::fileTag contentType() const;
+        inline vtk::fileTag contentType() const noexcept;
 
         //- The output options in use
-        inline vtk::outputOptions opts() const;
+        inline vtk::outputOptions opts() const noexcept;
 
         //- File extension for current format type.
         inline word ext() const;
 
         //- Commonly used query
-        inline bool legacy() const;
+        inline bool legacy() const noexcept;
 
         //- Parallel output requested?
         inline bool parallel() const noexcept;
@@ -258,7 +260,11 @@ public:
         //  If the file name has an extension, it will be used where if
         //  appropriate or changed to suit the format (legacy/xml) type.
         //  \note Expected calling states: (CLOSED).
-        bool open(const fileName& file, bool parallel=Pstream::parRun());
+        virtual bool open
+        (
+            const fileName& file,
+            bool parallel = Pstream::parRun()
+        );
 
         //- End the file contents and close the file after writing.
         //  \note Expected calling states: (PIECE | CELL_DATA | POINT_DATA).

src/fileFormats/vtk/file/foamVtkFileWriterI.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -53,13 +53,13 @@ inline bool Foam::vtk::fileWriter::notState(outputState test) const noexcept
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-inline Foam::vtk::fileTag Foam::vtk::fileWriter::contentType() const
+inline Foam::vtk::fileTag Foam::vtk::fileWriter::contentType() const noexcept
 {
     return contentType_;
 }
 
 
-inline Foam::vtk::outputOptions Foam::vtk::fileWriter::opts() const
+inline Foam::vtk::outputOptions Foam::vtk::fileWriter::opts() const noexcept
 {
     return opts_;
 }
@@ -71,7 +71,7 @@ inline Foam::word Foam::vtk::fileWriter::ext() const
 }
 
 
-inline bool Foam::vtk::fileWriter::legacy() const
+inline bool Foam::vtk::fileWriter::legacy() const noexcept
 {
     return opts_.legacy();
 }

src/fileFormats/vtk/file/foamVtmWriter.C

@@ -40,7 +40,7 @@ void Foam::vtk::vtmWriter::vtmEntry::clear()
 }
 
 
-bool Foam::vtk::vtmWriter::vtmEntry::good() const
+bool Foam::vtk::vtmWriter::vtmEntry::good() const noexcept
 {
     return
     (
@@ -397,9 +397,7 @@ Foam::label Foam::vtk::vtmWriter::beginBlock(const word& blockName)
 
 Foam::label Foam::vtk::vtmWriter::endBlock(const word& blockName)
 {
-    label nblock = blocks_.size();
+    if (!blocks_.empty())
-
-    if (nblock)
     {
         const word curr(blocks_.remove());
 

src/fileFormats/vtk/file/foamVtmWriter.H

@@ -118,7 +118,7 @@ class vtmWriter
             vtmEntry& operator=(const vtmEntry&) = default;
             vtmEntry& operator=(vtmEntry&&) = default;
 
-            //- Construct null
+            //- Default construct
             vtmEntry()
             :
                 type_(NONE)
@@ -157,7 +157,7 @@ class vtmWriter
         // Member Functions
 
             //- Test the type
-            bool isType(Type what) const
+            bool isType(Type what) const noexcept
             {
                return type_ == what;
             }
@@ -166,7 +166,7 @@ class vtmWriter
             void clear();
 
             //- True if the entry is good.
-            bool good() const;
+            bool good() const noexcept;
 
             //- Output valid entry as XML
             bool write(vtk::formatter& format) const;
@@ -207,7 +207,7 @@ public:
 
     // Constructors
 
-        //- Construct null, with autoName on
+        //- Default construct, with autoName on
         vtmWriter();
 
         //- Construct with specified behaviour for autoName

src/fileFormats/vtk/format/foamVtkAppendBase64Formatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -53,7 +53,7 @@ namespace vtk
 
 class appendBase64Formatter
 :
-    public foamVtkBase64Layer
+    public vtk::foamVtkBase64Layer
 {
     // Private Data Members
 
@@ -78,7 +78,7 @@ public:
     // Constructors
 
         //- Construct and attach to an output stream
-        appendBase64Formatter(std::ostream& os);
+        explicit appendBase64Formatter(std::ostream& os);
 
 
     //- Destructor. Closes/flushes the underlying layer.
@@ -88,7 +88,7 @@ public:
     // Member Functions
 
         //- The output is APPEND_BASE64.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Output name for XML type ("append")
         virtual const char* name() const;
@@ -101,6 +101,7 @@ public:
         virtual uint64_t offset(const uint64_t numbytes);
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkAppendRawFormatter.C

@@ -54,7 +54,7 @@ void Foam::vtk::appendRawFormatter::write
 
 Foam::vtk::appendRawFormatter::appendRawFormatter(std::ostream& os)
 :
-    formatter(os),
+    vtk::formatter(os),
     offset_(0)
 {}
 

src/fileFormats/vtk/format/foamVtkAppendRawFormatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -52,7 +52,7 @@ namespace vtk
 
 class appendRawFormatter
 :
-    public formatter
+    public vtk::formatter
 {
     // Private Data Members
 
@@ -64,7 +64,12 @@ class appendRawFormatter
         uint64_t offset_;
 
 
-    // Private Member Functions
+protected:
+
+    // Protected Member Functions
+
+        //- Write
+        void write(const char* s, std::streamsize n);
 
         //- No copy construct
         appendRawFormatter(const appendRawFormatter&) = delete;
@@ -73,20 +78,12 @@ class appendRawFormatter
         void operator=(const appendRawFormatter&) = delete;
 
 
-protected:
-
-    // Protected Member Functions
-
-        //- Write
-        void write(const char* s, std::streamsize n);
-
-
 public:
 
     // Constructors
 
         //- Construct and attach to an output stream
-        appendRawFormatter(std::ostream& os);
+        explicit appendRawFormatter(std::ostream& os);
 
 
     //- Destructor
@@ -96,7 +93,7 @@ public:
     // Member Functions
 
         //- The output is APPEND_BINARY.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Output name for XML type ("append")
         virtual const char* name() const;
@@ -122,9 +119,9 @@ public:
 
         //- A no-op for this format
         virtual void flush();
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkAsciiFormatter.C

@@ -68,7 +68,7 @@ inline void Foam::vtk::asciiFormatter::done()
 
 Foam::vtk::asciiFormatter::asciiFormatter(std::ostream& os)
 :
-    formatter(os),
+    vtk::formatter(os),
     pos_(0)
 {}
 
@@ -76,13 +76,13 @@ Foam::vtk::asciiFormatter::asciiFormatter(std::ostream& os)
 Foam::vtk::asciiFormatter::asciiFormatter
 (
     std::ostream& os,
-    unsigned precision
+    unsigned prec
 )
 :
-    formatter(os),
+    vtk::formatter(os),
     pos_(0)
 {
-    os.precision(precision);
+    os.precision(prec);
 }
 
 

src/fileFormats/vtk/format/foamVtkAsciiFormatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -54,7 +54,7 @@ namespace vtk
 
 class asciiFormatter
 :
-    public formatter
+    public vtk::formatter
 {
     // Private Data Members
 
@@ -89,10 +89,10 @@ public:
     // Constructors
 
         //- Construct and attach to an output stream, use default precision
-        asciiFormatter(std::ostream& os);
+        explicit asciiFormatter(std::ostream& os);
 
         //- Construct and attach to an output stream, use specified precision
-        asciiFormatter(std::ostream& os, unsigned precision);
+        asciiFormatter(std::ostream& os, unsigned prec);
 
 
     //- Destructor. Finishes the output line as required.
@@ -102,7 +102,7 @@ public:
     // Member Functions
 
         //- The output is INLINE_ASCII.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Name for the XML output type ("ascii")
         virtual const char* name() const;
@@ -127,9 +127,9 @@ public:
         //- The encoded length for ascii output is not applicable.
         //  \return 0
         virtual std::size_t encodedLength(std::size_t ignored) const;
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkBase64Formatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2017 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -51,7 +51,7 @@ namespace vtk
 
 class base64Formatter
 :
-    public foamVtkBase64Layer
+    public vtk::foamVtkBase64Layer
 {
     // Private Data Members
 
@@ -73,7 +73,7 @@ public:
     // Constructors
 
         //- Construct and attach to an output stream
-        base64Formatter(std::ostream& os);
+        explicit base64Formatter(std::ostream& os);
 
 
     //- Destructor. Closes/flushes the underlying layer.
@@ -83,7 +83,7 @@ public:
     // Member Functions
 
         //- The output is INLINE_BASE64.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Name for the XML output type ("binary")
         virtual const char* name() const;
@@ -92,9 +92,9 @@ public:
         //- End the encoding sequence (padding the final characters with '=')
         //  and write a newline to the output if any encoding was done.
         virtual void flush();
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkBase64Layer.C

@@ -41,7 +41,7 @@ void Foam::vtk::foamVtkBase64Layer::write
     std::streamsize n
 )
 {
-    base64Layer::write(s, n);
+    Foam::base64Layer::write(s, n);
 }
 
 
@@ -49,8 +49,8 @@ void Foam::vtk::foamVtkBase64Layer::write
 
 Foam::vtk::foamVtkBase64Layer::foamVtkBase64Layer(std::ostream& os)
 :
-    formatter(os),
+    vtk::formatter(os),
-    base64Layer(os)
+    Foam::base64Layer(os)
 {}
 
 
@@ -58,7 +58,7 @@ Foam::vtk::foamVtkBase64Layer::foamVtkBase64Layer(std::ostream& os)
 
 Foam::vtk::foamVtkBase64Layer::~foamVtkBase64Layer()
 {
-    base64Layer::close();
+    Foam::base64Layer::close();
 }
 
 
@@ -79,7 +79,7 @@ bool Foam::vtk::foamVtkBase64Layer::writeSize(const uint64_t numbytes)
 
 void Foam::vtk::foamVtkBase64Layer::write(const uint8_t val)
 {
-    base64Layer::add(val);
+    Foam::base64Layer::add(val);
 }
 
 
@@ -120,13 +120,13 @@ void Foam::vtk::foamVtkBase64Layer::write(const double val)
 
 void Foam::vtk::foamVtkBase64Layer::flush()
 {
-    base64Layer::close();
+    Foam::base64Layer::close();
 }
 
 
 std::size_t Foam::vtk::foamVtkBase64Layer::encodedLength(std::size_t n) const
 {
-    return base64Layer::encodedLength(n);
+    return Foam::base64Layer::encodedLength(n);
 }
 
 

src/fileFormats/vtk/format/foamVtkBase64Layer.H

@@ -50,23 +50,14 @@ namespace vtk
 
 class foamVtkBase64Layer
 :
-    public formatter,
+    public vtk::formatter,
-    protected base64Layer
+    protected Foam::base64Layer
 {
     // Private Data Members
 
         static const char* encoding_;
 
 
-    // Private Member Functions
-
-        //- No copy construct
-        foamVtkBase64Layer(const foamVtkBase64Layer&) = delete;
-
-        //- No copy assignment
-        void operator=(const foamVtkBase64Layer&) = delete;
-
-
 protected:
 
     // Protected Member Functions
@@ -74,11 +65,17 @@ protected:
         //- Write
         void write(const char* s, std::streamsize n);
 
+        //- No copy construct
+        foamVtkBase64Layer(const foamVtkBase64Layer&) = delete;
+
+        //- No copy assignment
+        void operator=(const foamVtkBase64Layer&) = delete;
+
 
     // Constructors
 
         //- Construct and attach to an output stream
-        foamVtkBase64Layer(std::ostream& os);
+        explicit foamVtkBase64Layer(std::ostream& os);
 
 public:
 
@@ -105,9 +102,9 @@ public:
 
         //- The encoded length for base64 encoded output.
         virtual std::size_t encodedLength(std::size_t n) const;
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkFormatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2018 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -132,7 +132,7 @@ protected:
     // Constructors
 
         //- Construct and attach to an output stream
-        inline formatter(std::ostream& os);
+        inline explicit formatter(std::ostream& os);
 
 
 public:
@@ -155,10 +155,10 @@ public:
     // Access
 
         //- Access to the underlying output stream
-        inline std::ostream& os();
+        inline std::ostream& os() noexcept;
 
         //- The format-type / output options.
-        virtual const outputOptions& opts() const = 0;
+        virtual const vtk::outputOptions& opts() const = 0;
 
         //- Name for the XML output type or the legacy output type.
         virtual const char* name() const = 0;
@@ -540,7 +540,6 @@ public:
                 dataName, formatter::npos, true
             );
         }
-
 };
 
 

src/fileFormats/vtk/format/foamVtkFormatterI.H

@@ -67,7 +67,7 @@ inline Foam::vtk::formatter::formatter(std::ostream& os)
 
 // * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
 
-inline std::ostream& Foam::vtk::formatter::os()
+inline std::ostream& Foam::vtk::formatter::os() noexcept
 {
     return os_;
 }

src/fileFormats/vtk/format/foamVtkLegacyAsciiFormatter.C

@@ -50,10 +50,10 @@ Foam::vtk::legacyAsciiFormatter::legacyAsciiFormatter
 Foam::vtk::legacyAsciiFormatter::legacyAsciiFormatter
 (
     std::ostream& os,
-    unsigned precision
+    unsigned prec
 )
 :
-    asciiFormatter(os, precision)
+    asciiFormatter(os, prec)
 {}
 
 

src/fileFormats/vtk/format/foamVtkLegacyAsciiFormatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2018 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -53,7 +53,7 @@ namespace vtk
 
 class legacyAsciiFormatter
 :
-    public asciiFormatter
+    public vtk::asciiFormatter
 {
     // Private Data Members
 
@@ -75,10 +75,10 @@ public:
     // Constructors
 
         //- Construct and attach to an output stream, use default precision
-        legacyAsciiFormatter(std::ostream& os);
+        explicit legacyAsciiFormatter(std::ostream& os);
 
         //- Construct and attach to an output stream, use specified precision
-        legacyAsciiFormatter(std::ostream& os, unsigned precision);
+        legacyAsciiFormatter(std::ostream& os, unsigned prec);
 
 
     //- Destructor
@@ -88,7 +88,7 @@ public:
     // Member Functions
 
         //- The output is LEGACY_ASCII.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Name for the legacy ascii output type ("ASCII")
         virtual const char* name() const;
@@ -107,9 +107,9 @@ public:
         inline virtual formatter& endPointData() { return *this; }
         inline virtual formatter& endPiece() { return *this; }
         inline virtual formatter& endVTKFile() { return *this; }
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/format/foamVtkLegacyRawFormatter.C

@@ -57,7 +57,7 @@ Foam::vtk::legacyRawFormatter::legacyRawFormatter
     std::ostream& os
 )
 :
-    formatter(os)
+    vtk::formatter(os)
 {}
 
 

src/fileFormats/vtk/format/foamVtkLegacyRawFormatter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2018 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -55,21 +55,12 @@ namespace vtk
 
 class legacyRawFormatter
 :
-    public formatter
+    public vtk::formatter
 {
     // Private Data Members
 
         static const char* legacyName_;
-        static const outputOptions opts_;
+        static const vtk::outputOptions opts_;
-
-
-    // Private Member Functions
-
-        //- No copy construct
-        legacyRawFormatter(const legacyRawFormatter&) = delete;
-
-        //- No copy assignment
-        void operator=(const legacyRawFormatter&) = delete;
 
 
 protected:
@@ -79,13 +70,19 @@ protected:
         //- Write
         void write(const char* s, std::streamsize n);
 
+        //- No copy construct
+        legacyRawFormatter(const legacyRawFormatter&) = delete;
+
+        //- No copy assignment
+        void operator=(const legacyRawFormatter&) = delete;
+
 
 public:
 
     // Constructors
 
         //- Construct and attach to an output stream
-        legacyRawFormatter(std::ostream& os);
+        explicit legacyRawFormatter(std::ostream& os);
 
 
     //- Destructor
@@ -95,7 +92,7 @@ public:
     // Member Functions
 
         //- The output is LEGACY_BINARY.
-        virtual const outputOptions& opts() const;
+        virtual const vtk::outputOptions& opts() const;
 
         //- Name for the legacy binary output type ("BINARY")
         virtual const char* name() const;
@@ -127,9 +124,9 @@ public:
         inline virtual formatter& endPointData() { return *this; }
         inline virtual formatter& endPiece() { return *this; }
         inline virtual formatter& endVTKFile() { return *this; }
-
 };
 
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 } // End namespace vtk

src/fileFormats/vtk/output/foamVtkOutput.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -254,11 +254,29 @@ namespace legacy
     //- Emit header for POINTS (with trailing newline).
     inline void beginPoints(std::ostream& os, label nPoints);
 
+    //- Emit header for VERTICES (with trailing newline).
+    //  The nConnectivity is the sum of all connectivity points used,
+    //  but \b without additional space for the size prefixes.
+    //  The additional prefix sizes are added internally.
+    //  \note With nConnectivity == 0, assume one point per element
+    inline void beginVerts
+    (
+        std::ostream& os,
+        label nVerts,
+        label nConnectivity = 0
+    );
+
     //- Emit header for LINES (with trailing newline).
     //  The nConnectivity is the sum of all connectivity points used,
     //  but \b without additional space for the size prefixes.
     //  The additional prefix sizes are added internally.
-    inline void beginLines(std::ostream& os, label nLines, label nConnectivity);
+    //  \note With nConnectivity == 0, assume two points per element
+    inline void beginLines
+    (
+        std::ostream& os,
+        label nLines,
+        label nConnectivity = 0
+    );
 
     //- Emit header for POLYGONS (with trailing newline).
     //  The nConnectivity is the sum of all connectivity points used,

src/fileFormats/vtk/output/foamVtkOutputI.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2017-2021 OpenCFD Ltd.
+    Copyright (C) 2017-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -119,6 +119,24 @@ inline void Foam::vtk::legacy::beginPoints(std::ostream& os, label nPoints)
 }
 
 
+inline void Foam::vtk::legacy::beginVerts
+(
+    std::ostream& os,
+    label nVerts,
+    label nConnectivity
+)
+{
+    if (!nConnectivity)
+    {
+        nConnectivity = nVerts;
+    }
+    os  << nl
+        << legacy::fileTagNames[vtk::fileTag::VERTS]
+        << ' ' << nVerts
+        << ' ' << (nVerts + nConnectivity) << nl;
+}
+
+
 inline void Foam::vtk::legacy::beginLines
 (
     std::ostream& os,
@@ -126,6 +144,10 @@ inline void Foam::vtk::legacy::beginLines
     label nConnectivity
 )
 {
+    if (!nConnectivity)
+    {
+        nConnectivity = 2*nLines;
+    }
     os  << nl
         << legacy::fileTagNames[vtk::fileTag::LINES]
         << ' ' << nLines

src/fileFormats/vtk/output/foamVtkOutputOptions.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2019 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -61,15 +61,15 @@ class outputOptions
 {
     // Private Member Data
 
-        //- The output style tuning
+        /// //- The output style tuning
-        enum styleType
+        /// enum styleType
-        {
+        /// {
-            NONE   = 0x00,  //!< Normal
+        ///     NONE   = 0x00,  //!< Normal
-            HEADER = 0x01   //!< Emit xml header
+        ///     HEADER = 0x01   //!< Emit xml header
-        };
+        /// };
 
         //- The output format type
-        formatType fmtType_;
+        vtk::formatType fmtType_;
 
         //- ASCII write precision
         mutable unsigned precision_;
@@ -79,15 +79,16 @@ public:
 
     // Constructors
 
-        //- Construct null - XML insitu ASCII format with default precision
+        //- Default construct - XML insitu ASCII format with default precision
         inline outputOptions();
 
         //- Construct with specified format and default (ASCII) precision
+        //
         //  \note This constructor should remain non-explicit.
-        inline outputOptions(enum formatType fmtType);
+        inline outputOptions(enum vtk::formatType fmtType);
 
         //- Construct with specified format and (ASCII) write precision
-        inline outputOptions(enum formatType fmtType, unsigned prec);
+        inline outputOptions(enum vtk::formatType fmtType, unsigned prec);
 
 
     // Selectors
@@ -101,28 +102,28 @@ public:
     // Access
 
         //- The output format type
-        inline formatType fmt() const;
+        inline vtk::formatType fmt() const noexcept;
 
         //- The file extension (legacy or xml) for the given content-type
         inline word ext(vtk::fileTag contentType) const;
 
         //- True if writer uses legacy file format
-        inline bool legacy() const;
+        inline bool legacy() const noexcept;
 
         //- True if writer uses XML file format (non-legacy)
-        inline bool xml() const;
+        inline bool xml() const noexcept;
 
         //- True if output format uses an append mode
-        inline bool append() const;
+        inline bool append() const noexcept;
 
         //- True if output format does not use an append mode
-        inline bool insitu() const;
+        inline bool insitu() const noexcept;
 
         //- True if output format is ASCII
-        inline bool ascii() const;
+        inline bool ascii() const noexcept;
 
         //- Return the ASCII write precision
-        inline unsigned precision() const;
+        inline unsigned precision() const noexcept;
 
 
     // Edit

src/fileFormats/vtk/output/foamVtkOutputOptionsI.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2019 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -25,8 +25,6 @@ License
 
 \*---------------------------------------------------------------------------*/
 
-#include "foamVtkOutput.H"
-
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 inline Foam::vtk::outputOptions::outputOptions()
@@ -38,7 +36,7 @@ inline Foam::vtk::outputOptions::outputOptions()
 
 inline Foam::vtk::outputOptions::outputOptions
 (
-    enum formatType fmtType
+    enum vtk::formatType fmtType
 )
 :
     fmtType_(fmtType),
@@ -48,7 +46,7 @@ inline Foam::vtk::outputOptions::outputOptions
 
 inline Foam::vtk::outputOptions::outputOptions
 (
-    enum formatType fmtType,
+    enum vtk::formatType fmtType,
     unsigned prec
 )
 :
@@ -68,7 +66,7 @@ Foam::vtk::outputOptions::newFormatter(std::ostream& os) const
 
 // * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * * //
 
-inline Foam::vtk::formatType Foam::vtk::outputOptions::fmt() const
+inline Foam::vtk::formatType Foam::vtk::outputOptions::fmt() const noexcept
 {
     return fmtType_;
 }
@@ -85,7 +83,7 @@ inline Foam::word Foam::vtk::outputOptions::ext(vtk::fileTag contentType) const
 }
 
 
-inline bool Foam::vtk::outputOptions::legacy() const
+inline bool Foam::vtk::outputOptions::legacy() const noexcept
 {
     return
     (
@@ -95,13 +93,13 @@ inline bool Foam::vtk::outputOptions::legacy() const
 }
 
 
-inline bool Foam::vtk::outputOptions::xml() const
+inline bool Foam::vtk::outputOptions::xml() const noexcept
 {
     return !legacy();
 }
 
 
-inline bool Foam::vtk::outputOptions::append() const
+inline bool Foam::vtk::outputOptions::append() const noexcept
 {
     return
     (
@@ -111,19 +109,19 @@ inline bool Foam::vtk::outputOptions::append() const
 }
 
 
-inline bool Foam::vtk::outputOptions::insitu() const
+inline bool Foam::vtk::outputOptions::insitu() const noexcept
 {
     return !append();
 }
 
 
-inline bool Foam::vtk::outputOptions::ascii() const
+inline bool Foam::vtk::outputOptions::ascii() const noexcept
 {
     return !(unsigned(fmtType_) & 0x0F);
 }
 
 
-inline unsigned Foam::vtk::outputOptions::precision() const
+inline unsigned Foam::vtk::outputOptions::precision() const noexcept
 {
     return precision_;
 }

src/fileFormats/vtk/write/foamVtkPolyWriter.C

@@ -67,6 +67,7 @@ void Foam::vtk::polyWriter::beginPiece
 {
     // Basic sizes
     nLocalPoints_ = points.size();
+    nLocalVerts_  = 0;
     nLocalLines_  = edges.size();
     nLocalPolys_  = 0;
 
@@ -104,6 +105,7 @@ void Foam::vtk::polyWriter::beginPiece
 {
     // Basic sizes
     nLocalPoints_ = points.size();
+    nLocalVerts_  = 0;
     nLocalLines_  = 0;
     nLocalPolys_  = faces.size();
 
@@ -568,6 +570,7 @@ Foam::vtk::polyWriter::polyWriter
     numberOfPoints_(0),
     numberOfCells_(0),
     nLocalPoints_(0),
+    nLocalVerts_(0),
     nLocalLines_(0),
     nLocalPolys_(0)
 {

src/fileFormats/vtk/write/foamVtkPolyWriter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2018-2021 OpenCFD Ltd.
+    Copyright (C) 2018-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -82,6 +82,9 @@ protected:
         //- Local number of points
         label nLocalPoints_;
 
+        //- Local number of vertices (points)
+        label nLocalVerts_;
+
         //- Local number of lines (edges)
         label nLocalLines_;
 

src/meshTools/Make/files

@@ -143,6 +143,7 @@ $(setWriters)/gltf/gltfSetWriterRunTime.C
 $(setWriters)/gnuplot/gnuplotSetWriterRunTime.C
 $(setWriters)/nastran/nastranSetWriterRunTime.C
 $(setWriters)/raw/rawSetWriterRunTime.C
+$(setWriters)/vtk/foamVtkCoordSetWriter.C
 $(setWriters)/vtk/vtkSetWriterRunTime.C
 $(setWriters)/xmgrace/xmgraceSetWriterRunTime.C
 

src/meshTools/coordSet/writers/vtk/foamVtkCoordSetWriter.C

@@ -0,0 +1,574 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2022 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "foamVtkCoordSetWriter.H"
+#include "foamVtkOutput.H"
+#include "globalIndex.H"
+
+// * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
+
+void Foam::vtk::coordSetWriter::beginPiece()
+{
+    // Basic sizes
+    nLocalPoints_ = 0;
+    nLocalVerts_  = 0;
+    nLocalLines_  = 0;
+    nLocalPolys_  = 0;
+
+    for (const pointField& pts : points_)
+    {
+        const label npts = pts.size();
+        nLocalPoints_ += npts;
+
+        if (npts)
+        {
+            ++nLocalLines_;
+        }
+    }
+
+    switch (elemOutput_)
+    {
+        case elemOutputType::NO_ELEMENTS:
+        {
+            nLocalVerts_ = nLocalLines_ = 0;
+            break;
+        }
+        case elemOutputType::DEFAULT_ELEMENTS:
+        {
+            if (points_.size() < 2)
+            {
+                //OR  nLocalVerts_ = nLocalPoints_;
+                nLocalVerts_ = 0;
+                nLocalLines_ = 0;
+            }
+            break;
+        }
+        case elemOutputType::POINT_ELEMENTS:
+        {
+            nLocalVerts_ = nLocalPoints_;
+            nLocalLines_ = 0;
+            break;
+        }
+        case elemOutputType::LINE_ELEMENTS:
+        {
+            // Already determined
+            break;
+        }
+    }
+
+    // Nothing else to do for legacy
+    if (legacy()) return;
+
+    if (format_)
+    {
+        format().openTag
+        (
+            vtk::fileTag::PIECE,
+            vtk::fileAttr::NUMBER_OF_POINTS, nLocalPoints_
+        );
+        if (nLocalVerts_)
+        {
+            format().xmlAttr(vtk::fileAttr::NUMBER_OF_VERTS, nLocalVerts_);
+        }
+        if (nLocalLines_)
+        {
+            format().xmlAttr(vtk::fileAttr::NUMBER_OF_LINES, nLocalLines_);
+        }
+        format().closeTag();
+    }
+}
+
+
+void Foam::vtk::coordSetWriter::writePoints()
+{
+    this->beginPoints(nLocalPoints_);
+
+    {
+        for (const pointField& pts : points_)
+        {
+            vtk::writeList(format(), pts);
+        }
+    }
+
+    this->endPoints();
+}
+
+
+void Foam::vtk::coordSetWriter::writeVertsLegacy()
+{
+    if (!nLocalVerts_)
+    {
+        return;  // Nothing to do
+    }
+
+    // connectivity = 1 per vertex
+    const label nLocalConns = nLocalVerts_;
+
+    legacy::beginVerts(os_, nLocalVerts_, nLocalConns);
+
+    labelList vertLabels(nLocalVerts_ + nLocalConns);
+
+    auto iter = vertLabels.begin();
+
+    for (label pointi = 0; pointi < nLocalVerts_; ++pointi)
+    {
+        *iter++ = 1;
+        *iter++ = pointi;
+    }
+
+    vtk::writeList(format(), vertLabels);
+
+    if (format_)
+    {
+        format().flush();
+    }
+}
+
+
+void Foam::vtk::coordSetWriter::writeLinesLegacy()
+{
+    if (!nLocalLines_)
+    {
+        return;  // Nothing to do
+    }
+
+    // connectivity = use each point
+    label nLocalConns = nLocalPoints_;
+
+    legacy::beginLines(os_, nLocalLines_, nLocalConns);
+
+    labelList vertLabels(nLocalLines_ + nLocalConns);
+
+    auto iter = vertLabels.begin();
+
+    label localPointi = 0;
+    for (const pointField& pts : points_)
+    {
+        label npts = pts.size();
+
+        if (npts)
+        {
+            *iter++ = npts;
+            while (npts--)
+            {
+                *iter++ = localPointi;
+                ++localPointi;
+            }
+        }
+    }
+
+    vtk::writeList(format(), vertLabels);
+
+    if (format_)
+    {
+        format().flush();
+    }
+}
+
+
+void Foam::vtk::coordSetWriter::writeVerts()
+{
+    if (!nLocalVerts_)
+    {
+        return;  // Nothing to do
+    }
+
+    // connectivity = 1 per vertex
+    const label nLocalConns = nLocalVerts_;
+
+    if (format_)
+    {
+        format().tag(vtk::fileTag::VERTS);
+    }
+
+    //
+    // 'offsets'  (connectivity offsets)
+    //
+    {
+        labelList vertOffsets(nLocalVerts_);
+        label nOffs = vertOffsets.size();
+
+        // if (parallel_)
+        // {
+        //     reduce(nOffs, sumOp<label>());
+        // }
+
+        if (format_)
+        {
+            const uint64_t payLoad = vtk::sizeofData<label>(nOffs);
+
+            format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
+            format().writeSize(payLoad);
+        }
+
+        // processor-local connectivity offsets
+
+        label off = 0;
+
+        /// label off =
+        /// (
+        ///     parallel_ ? globalIndex(nLocalConns).localStart() : 0
+        /// );
+
+        auto iter = vertOffsets.begin();
+
+        for (label pointi = 0; pointi < nLocalVerts_; ++pointi)
+        {
+            off += 1;  // End offset
+            *iter = off;
+            ++iter;
+        }
+
+        vtk::writeList(format_.ref(), vertOffsets);
+
+        if (format_)
+        {
+            format().flush();
+            format().endDataArray();
+        }
+    }
+
+    //
+    // 'connectivity'
+    //
+    {
+        labelList vertLabels(nLocalConns);
+
+        label nConns = nLocalConns;
+
+        // if (parallel_)
+        // {
+        //     reduce(nConns, sumOp<label>());
+        // }
+
+        if (format_)
+        {
+            const uint64_t payLoad = vtk::sizeofData<label>(nConns);
+
+            format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
+            format().writeSize(payLoad * sizeof(label));
+        }
+
+        {
+            // XML: connectivity only
+            // [id1, id2, ..., id1, id2, ...]
+
+            auto iter = vertLabels.begin();
+
+            for (label pointi = 0; pointi < nLocalVerts_; ++pointi)
+            {
+                *iter++ = pointi;
+            }
+        }
+
+        vtk::writeList(format(), vertLabels);
+
+        if (format_)
+        {
+            format().flush();
+            format().endDataArray();
+        }
+    }
+
+
+    if (format_)
+    {
+        format().endTag(vtk::fileTag::VERTS);
+    }
+}
+
+
+void Foam::vtk::coordSetWriter::writeLines()
+{
+    if (!nLocalLines_)
+    {
+        return;  // Nothing to do
+    }
+
+    // connectivity = use each point
+    label nLocalConns = nLocalPoints_;
+
+    if (format_)
+    {
+        format().tag(vtk::fileTag::LINES);
+    }
+
+    //
+    // 'offsets'  (connectivity offsets)
+    //
+    {
+        labelList vertOffsets(nLocalLines_);
+        label nOffs = vertOffsets.size();
+
+        // if (parallel_)
+        // {
+        //     reduce(nOffs, sumOp<label>());
+        // }
+
+        if (format_)
+        {
+            const uint64_t payLoad = vtk::sizeofData<label>(nOffs);
+
+            format().beginDataArray<label>(vtk::dataArrayAttr::OFFSETS);
+            format().writeSize(payLoad);
+        }
+
+        // processor-local connectivity offsets
+
+        label off = 0;
+
+        /// label off =
+        /// (
+        ///     parallel_ ? globalIndex(nLocalConns).localStart() : 0
+        /// );
+
+        auto iter = vertOffsets.begin();
+
+        for (const pointField& pts : points_)
+        {
+            const label npts = pts.size();
+
+            if (npts)
+            {
+                off += npts;  // End offset
+                *iter = off;
+                ++iter;
+            }
+        }
+
+        vtk::writeList(format_.ref(), vertOffsets);
+
+        if (format_)
+        {
+            format().flush();
+            format().endDataArray();
+        }
+    }
+
+    //
+    // 'connectivity'
+    //
+    {
+        labelList vertLabels(nLocalConns);
+
+        label nConns = nLocalConns;
+
+        // if (parallel_)
+        // {
+        //     reduce(nConns, sumOp<label>());
+        // }
+
+        if (format_)
+        {
+            const uint64_t payLoad = vtk::sizeofData<label>(nConns);
+
+            format().beginDataArray<label>(vtk::dataArrayAttr::CONNECTIVITY);
+            format().writeSize(payLoad * sizeof(label));
+        }
+
+        {
+            // XML: connectivity only
+            // [id1, id2, ..., id1, id2, ...]
+
+            auto iter = vertLabels.begin();
+
+            label localPointi = 0;
+            for (const pointField& pts : points_)
+            {
+                label npts = pts.size();
+
+                while (npts--)
+                {
+                    *iter++ = localPointi;
+                    ++localPointi;
+                }
+            }
+        }
+
+
+        vtk::writeList(format(), vertLabels);
+
+        if (format_)
+        {
+            format().flush();
+            format().endDataArray();
+        }
+    }
+
+    if (format_)
+    {
+        format().endTag(vtk::fileTag::LINES);
+    }
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::vtk::coordSetWriter::coordSetWriter
+(
+    const UPtrList<const pointField>& points,
+    const vtk::outputOptions opts
+)
+:
+    vtk::polyWriter(opts),
+
+    points_(points),
+    instant_(),
+    elemOutput_(DEFAULT_ELEMENTS)
+{}
+
+
+Foam::vtk::coordSetWriter::coordSetWriter
+(
+    const UPtrList<const pointField>& points,
+    const fileName& file,
+    bool parallel
+)
+:
+    coordSetWriter(points)
+{
+    open(file, parallel);
+}
+
+
+Foam::vtk::coordSetWriter::coordSetWriter
+(
+    const UPtrList<const pointField>& points,
+    const vtk::outputOptions opts,
+    const fileName& file,
+    bool parallel
+)
+:
+    coordSetWriter(points, opts)
+{
+    open(file, parallel);
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+void Foam::vtk::coordSetWriter::setElementType
+(
+    const elemOutputType elemOutput
+)
+{
+    elemOutput_ = elemOutput;
+}
+
+
+bool Foam::vtk::coordSetWriter::open
+(
+    const fileName& file,
+    bool parallel
+)
+{
+    return vtk::polyWriter::open(file, false);  // non-parallel only
+}
+
+
+void Foam::vtk::coordSetWriter::setTime(const instant& inst)
+{
+    instant_ = inst;
+}
+
+
+bool Foam::vtk::coordSetWriter::beginFile(std::string title)
+{
+    if (title.size())
+    {
+        return vtk::fileWriter::beginFile(title);
+    }
+
+    if (!instant_.name().empty())
+    {
+        return vtk::fileWriter::beginFile
+        (
+            "time='" + instant_.name() + "'"
+        );
+    }
+
+    // Provide default title
+    return vtk::fileWriter::beginFile("coord-set");
+}
+
+
+bool Foam::vtk::coordSetWriter::writeGeometry()
+{
+    enter_Piece();
+
+    beginPiece();
+
+    writePoints();
+
+    //const label pointOffset =
+    //(
+    //   parallel_ ? globalIndex(nLocalPoints_).localStart() : 0
+    //);
+
+    if (legacy())
+    {
+        writeVertsLegacy();
+        writeLinesLegacy();
+    }
+    else
+    {
+        writeVerts();
+        writeLines();
+    }
+
+    return true;
+}
+
+
+void Foam::vtk::coordSetWriter::writeTimeValue()
+{
+    if (!instant_.name().empty())
+    {
+        vtk::fileWriter::writeTimeValue(instant_.value());
+    }
+}
+
+
+void Foam::vtk::coordSetWriter::piece
+(
+    const UPtrList<const pointField>& points
+)
+{
+    endPiece();
+
+    points_ = points;
+}
+
+
+bool Foam::vtk::coordSetWriter::writeProcIDs()
+{
+    // Ignore
+    return false;
+}
+
+
+// ************************************************************************* //

src/meshTools/coordSet/writers/vtk/foamVtkCoordSetWriter.H

@@ -0,0 +1,236 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2022 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+Class
+    Foam::vtk::coordSetWriter
+
+Description
+    Write as points/lines, optionally with fields,
+    as a vtp file or a legacy vtk file.
+
+    The file output states are managed by the Foam::vtk::fileWriter class.
+    FieldData (eg, TimeValue) must appear before any geometry pieces.
+
+Note
+    Non-parallel only
+
+SourceFiles
+    foamVtkCoordSetWriter.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef Foam_vtk_coordSetWriter_H
+#define Foam_vtk_coordSetWriter_H
+
+#include "foamVtkPolyWriter.H"
+#include "UPtrList.H"
+#include "Field.H"
+#include "instant.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace vtk
+{
+
+/*---------------------------------------------------------------------------*\
+                     Class vtk::coordSetWriter Declaration
+\*---------------------------------------------------------------------------*/
+
+class coordSetWriter
+:
+    public vtk::polyWriter
+{
+public:
+
+    // Data Types
+
+        //- Types of element output.
+        enum elemOutputType
+        {
+            NO_ELEMENTS = 0,
+            DEFAULT_ELEMENTS = 1,
+            POINT_ELEMENTS = 2,
+            LINE_ELEMENTS = 3
+        };
+
+private:
+
+    // Private Member Data
+
+        //- Reference to the points
+        UPtrList<const pointField> points_;
+
+        //- Time name/value
+        instant instant_;
+
+        //- Preferred output element type
+        elemOutputType elemOutput_;
+
+
+    // Private Member Functions
+
+
+    // Private Member Functions
+
+        //- Determine sizes (nLocalPoints_, nLocalLines_),
+        //- and begin piece
+        void beginPiece();
+
+        //- Write points
+        void writePoints();
+
+        //- Write vertices, legacy format
+        //  \param pointOffset processor-local point offset
+        void writeVertsLegacy();
+
+        //- Write vertices
+        //  \param pointOffset processor-local point offset
+        void writeVerts();
+
+        //- Write lines, legacy format
+        //  \param pointOffset processor-local point offset
+        void writeLinesLegacy();
+
+        //- Write lines
+        //  \param pointOffset processor-local point offset
+        void writeLines();
+
+
+        //- No copy construct
+        coordSetWriter(const coordSetWriter&) = delete;
+
+        //- No copy assignment
+        void operator=(const coordSetWriter&) = delete;
+
+
+public:
+
+    // Constructors
+
+        //- Construct from components (default format INLINE_BASE64)
+        coordSetWriter
+        (
+            const UPtrList<const pointField>& pts,
+            const vtk::outputOptions opts = vtk::formatType::INLINE_BASE64
+        );
+
+        //- Construct from components (default format INLINE_BASE64),
+        //- and open the file for writing.
+        //  The file name is with/without an extension.
+        coordSetWriter
+        (
+            const UPtrList<const pointField>& pts,
+            const fileName& file,
+            bool paralel = false  /* ignored: always false */
+        );
+
+        //- Construct from components and open the file for writing.
+        //  The file name is with/without an extension.
+        coordSetWriter
+        (
+            const UPtrList<const pointField>& pts,
+            const vtk::outputOptions opts,
+            const fileName& file,
+            bool paralel = false  /* ignored: always false */
+        );
+
+
+    //- Destructor
+    virtual ~coordSetWriter() = default;
+
+
+    // Member Functions
+
+        //- Define preferred element type
+        void setElementType(const elemOutputType elemOutput);
+
+        //- Open file for writing. Non-parallel only
+        virtual bool open
+        (
+            const fileName& file,
+            bool parallel = false  /* ignored: always false */
+        );
+
+        //- Define a time name/value for the output
+        virtual void setTime(const instant& inst);
+
+        //- Write file header (non-collective)
+        //  \note Expected calling states: (OPENED).
+        virtual bool beginFile(std::string title = "");
+
+        //- Write patch topology
+        //  Also writes the file header if not previously written.
+        //  \note Must be called prior to writing CellData or PointData
+        virtual bool writeGeometry();
+
+        //- Write "TimeValue" FieldData (name as per Catalyst output)
+        //  Must be called within the FIELD_DATA state.
+        //  \note As a convenience this can also be called from
+        //      (OPENED | DECLARED) states, in which case it invokes
+        //      beginFieldData(1) internally.
+        using vtk::fileWriter::writeTimeValue;
+
+        //- Write the currently set time as "TimeValue" FieldData
+        void writeTimeValue();
+
+        //- Reset point references to begin a new piece
+        void piece(const UPtrList<const pointField>& points);
+
+
+        //- Write processor ids for each line as CellData
+        //- (no-op in serial)
+        bool writeProcIDs();
+
+
+    // Write
+
+        //- Write primitive field of PointData
+        template<class Type>
+        void writePointData
+        (
+            const word& fieldName,
+            const UPtrList<const Field<Type>>& fieldPtrs
+        );
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace vtk
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "foamVtkCoordSetWriterTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/meshTools/coordSet/writers/vtk/foamVtkCoordSetWriterTemplates.C

@@ -0,0 +1,81 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2022 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM is free software: you can redistribute it and/or modify it
+    under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+    for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class Type>
+void Foam::vtk::coordSetWriter::writePointData
+(
+    const word& fieldName,
+    const UPtrList<const Field<Type>>& fieldPtrs
+)
+{
+    // Could check sizes:
+
+    if (isState(outputState::POINT_DATA))
+    {
+        ++nPointData_;
+    }
+    else
+    {
+        reportBadState(FatalErrorInFunction, outputState::POINT_DATA)
+            << " for field " << fieldName << nl << endl
+            << exit(FatalError);
+        return;
+    }
+
+    label nValues = 0;
+
+    for (const Field<Type>& field : fieldPtrs)
+    {
+        nValues += field.size();
+    }
+
+    // if (parallel_)
+    // {
+    //     reduce(nValues, sumOp<label>());
+    // }
+
+    this->beginDataArray<Type>(fieldName, nValues);
+
+    // if (parallel_)
+    // {
+    //     vtk::writeListParallel(format_.ref(), field);
+    // }
+    // else
+    {
+        for (const Field<Type>& field : fieldPtrs)
+        {
+            vtk::writeList(format(), field);
+        }
+    }
+
+    this->endDataArray();
+}
+
+
+// ************************************************************************* //

src/meshTools/output/vtk/patch/foamVtkPatchMeshWriter.C

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -39,7 +39,7 @@ void Foam::vtk::patchMeshWriter::beginPiece()
     const polyBoundaryMesh& patches = mesh_.boundaryMesh();
 
     nLocalPoints_ = nLocalPolys_ = 0;
-    nLocalVerts_ = 0;
+    nLocalPolyConn_ = 0;
 
     for (const label patchId : patchIDs_)
     {
@@ -50,7 +50,7 @@ void Foam::vtk::patchMeshWriter::beginPiece()
 
         for (const face& f : pp)
         {
-            nLocalVerts_ += f.size();
+            nLocalPolyConn_ += f.size();
         }
     }
 
@@ -150,12 +150,12 @@ void Foam::vtk::patchMeshWriter::writePolysLegacy(const label pointOffset)
     // Connectivity count without additional storage (done internally)
 
     label nPolys = nLocalPolys_;
-    label nVerts = nLocalVerts_;
+    label nPolyConn = nLocalPolyConn_;
 
     if (parallel_)
     {
         reduce(nPolys, sumOp<label>());
-        reduce(nVerts, sumOp<label>());
+        reduce(nPolyConn, sumOp<label>());
     }
 
     if (nPolys != numberOfCells_)
@@ -166,9 +166,9 @@ void Foam::vtk::patchMeshWriter::writePolysLegacy(const label pointOffset)
             << exit(FatalError);
     }
 
-    legacy::beginPolys(os_, nPolys, nVerts);
+    legacy::beginPolys(os_, nPolys, nPolyConn);
 
-    labelList vertLabels(nLocalPolys_ + nLocalVerts_);
+    labelList vertLabels(nLocalPolys_ + nLocalPolyConn_);
 
     {
         // Legacy: size + connectivity together
@@ -227,9 +227,9 @@ void Foam::vtk::patchMeshWriter::writePolys(const label pointOffset)
     // 'connectivity'
     //
     {
-        labelList vertLabels(nLocalVerts_);
+        labelList vertLabels(nLocalPolyConn_);
 
-        label nVerts = nLocalVerts_;
+        label nVerts = nLocalPolyConn_;
 
         if (parallel_)
         {
@@ -312,7 +312,7 @@ void Foam::vtk::patchMeshWriter::writePolys(const label pointOffset)
         // processor-local connectivity offsets
         label off =
         (
-            parallel_ ? globalIndex(nLocalVerts_).localStart() : 0
+            parallel_ ? globalIndex(nLocalPolyConn_).localStart() : 0
         );
 
 
@@ -369,7 +369,7 @@ Foam::vtk::patchMeshWriter::patchMeshWriter
     numberOfCells_(0),
     nLocalPoints_(0),
     nLocalPolys_(0),
-    nLocalVerts_(0),
+    nLocalPolyConn_(0),
 
     mesh_(mesh),
     patchIDs_(patchIDs)

src/meshTools/output/vtk/patch/foamVtkPatchMeshWriter.H

@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2016-2021 OpenCFD Ltd.
+    Copyright (C) 2016-2022 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -85,8 +85,8 @@ protected:
         //- Local number of polys (faces)
         label nLocalPolys_;
 
-        //- Local face vertices (connectivity) count. Sum of face sizes.
+        //- Local connectivity count for polys (faces) == sum of face sizes
-        label nLocalVerts_;
+        label nLocalPolyConn_;
 
         //- Reference to the OpenFOAM mesh (or subset)
         const polyMesh& mesh_;