.blend file format of Blender: JavaScript parsing library

Blender is an open source suite for 3D modelling, sculpting, animation, compositing, rendering, preparation of assets for its own game engine and exporting to others, etc. .blend is its own binary format that saves whole state of suite: current scene, animations, all software settings, extensions, etc.

Internally, .blend format is a hybrid semi-self-descriptive format. On top level, it contains a simple header and a sequence of file blocks, which more or less follow typical TLV pattern. Pre-last block would be a structure with code DNA1, which is a essentially a machine-readable schema of all other structures used in this file.

Application

Blender

File extension

blend

KS implementation details

License: CC0-1.0

References

This page hosts a formal specification of .blend file format of Blender using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for JavaScript generated by Kaitai Struct depends on the JavaScript runtime library. You have to install it before you can parse data.

The JavaScript runtime library is available at npm:

npm install kaitai-struct

Code

See the usage examples in the JavaScript notes.

Parse structure from an ArrayBuffer:

var arrayBuffer = ...;
var data = new BlenderBlend(new KaitaiStream(arrayBuffer));

After that, one can get various attributes from the structure by accessing fields or properties like:

data.hdr // => get hdr

JavaScript source code to parse .blend file format of Blender

BlenderBlend.js

// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

(function (root, factory) {
  if (typeof define === 'function' && define.amd) {
    define(['kaitai-struct/KaitaiStream'], factory);
  } else if (typeof module === 'object' && module.exports) {
    module.exports = factory(require('kaitai-struct/KaitaiStream'));
  } else {
    root.BlenderBlend = factory(root.KaitaiStream);
  }
}(this, function (KaitaiStream) {
/**
 * Blender is an open source suite for 3D modelling, sculpting,
 * animation, compositing, rendering, preparation of assets for its own
 * game engine and exporting to others, etc. `.blend` is its own binary
 * format that saves whole state of suite: current scene, animations,
 * all software settings, extensions, etc.
 * 
 * Internally, .blend format is a hybrid semi-self-descriptive
 * format. On top level, it contains a simple header and a sequence of
 * file blocks, which more or less follow typical [TLV
 * pattern](https://en.wikipedia.org/wiki/Type-length-value). Pre-last
 * block would be a structure with code `DNA1`, which is a essentially
 * a machine-readable schema of all other structures used in this file.
 */

var BlenderBlend = (function() {
  BlenderBlend.PtrSize = Object.freeze({
    BITS_64: 45,
    BITS_32: 95,

    45: "BITS_64",
    95: "BITS_32",
  });

  BlenderBlend.Endian = Object.freeze({
    BE: 86,
    LE: 118,

    86: "BE",
    118: "LE",
  });

  function BlenderBlend(_io, _parent, _root) {
    this._io = _io;
    this._parent = _parent;
    this._root = _root || this;

    this._read();
  }
  BlenderBlend.prototype._read = function() {
    this.hdr = new Header(this._io, this, this._root);
    this.blocks = [];
    var i = 0;
    while (!this._io.isEof()) {
      this.blocks.push(new FileBlock(this._io, this, this._root));
      i++;
    }
  }

  /**
   * DNA struct contains a `type` (type name), which is specified as
   * an index in types table, and sequence of fields.
   */

  var DnaStruct = BlenderBlend.DnaStruct = (function() {
    function DnaStruct(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    DnaStruct.prototype._read = function() {
      this.idxType = this._io.readU2le();
      this.numFields = this._io.readU2le();
      this.fields = new Array(this.numFields);
      for (var i = 0; i < this.numFields; i++) {
        this.fields[i] = new DnaField(this._io, this, this._root);
      }
    }
    Object.defineProperty(DnaStruct.prototype, 'type', {
      get: function() {
        if (this._m_type !== undefined)
          return this._m_type;
        this._m_type = this._parent.types[this.idxType];
        return this._m_type;
      }
    });

    return DnaStruct;
  })();

  var FileBlock = BlenderBlend.FileBlock = (function() {
    function FileBlock(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    FileBlock.prototype._read = function() {
      this.code = KaitaiStream.bytesToStr(this._io.readBytes(4), "ASCII");
      this.lenBody = this._io.readU4le();
      this.memAddr = this._io.readBytes(this._root.hdr.psize);
      this.sdnaIndex = this._io.readU4le();
      this.count = this._io.readU4le();
      switch (this.code) {
      case "DNA1":
        this._raw_body = this._io.readBytes(this.lenBody);
        var _io__raw_body = new KaitaiStream(this._raw_body);
        this.body = new Dna1Body(_io__raw_body, this, this._root);
        break;
      default:
        this.body = this._io.readBytes(this.lenBody);
        break;
      }
    }
    Object.defineProperty(FileBlock.prototype, 'sdnaStruct', {
      get: function() {
        if (this._m_sdnaStruct !== undefined)
          return this._m_sdnaStruct;
        if (this.sdnaIndex != 0) {
          this._m_sdnaStruct = this._root.sdnaStructs[this.sdnaIndex];
        }
        return this._m_sdnaStruct;
      }
    });

    /**
     * Identifier of the file block
     */

    /**
     * Total length of the data after the header of file block
     */

    /**
     * Memory address the structure was located when written to disk
     */

    /**
     * Index of the SDNA structure
     */

    /**
     * Number of structure located in this file-block
     */

    return FileBlock;
  })();

  /**
   * DNA1, also known as "Structure DNA", is a special block in
   * .blend file, which contains machine-readable specifications of
   * all other structures used in this .blend file.
   * 
   * Effectively, this block contains:
   * 
   * * a sequence of "names" (strings which represent field names)
   * * a sequence of "types" (strings which represent type name)
   * * a sequence of "type lengths"
   * * a sequence of "structs" (which describe contents of every
   *   structure, referring to types and names by index)
   * @see {@link https://en.blender.org/index.php/Dev:Source/Architecture/File_Format#Structure_DNA|Source}
   */

  var Dna1Body = BlenderBlend.Dna1Body = (function() {
    function Dna1Body(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    Dna1Body.prototype._read = function() {
      this.id = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.id, [83, 68, 78, 65]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([83, 68, 78, 65], this.id, this._io, "/types/dna1_body/seq/0");
      }
      this.nameMagic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.nameMagic, [78, 65, 77, 69]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([78, 65, 77, 69], this.nameMagic, this._io, "/types/dna1_body/seq/1");
      }
      this.numNames = this._io.readU4le();
      this.names = new Array(this.numNames);
      for (var i = 0; i < this.numNames; i++) {
        this.names[i] = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "UTF-8");
      }
      this.padding1 = this._io.readBytes(KaitaiStream.mod((4 - this._io.pos), 4));
      this.typeMagic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.typeMagic, [84, 89, 80, 69]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([84, 89, 80, 69], this.typeMagic, this._io, "/types/dna1_body/seq/5");
      }
      this.numTypes = this._io.readU4le();
      this.types = new Array(this.numTypes);
      for (var i = 0; i < this.numTypes; i++) {
        this.types[i] = KaitaiStream.bytesToStr(this._io.readBytesTerm(0, false, true, true), "UTF-8");
      }
      this.padding2 = this._io.readBytes(KaitaiStream.mod((4 - this._io.pos), 4));
      this.tlenMagic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.tlenMagic, [84, 76, 69, 78]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([84, 76, 69, 78], this.tlenMagic, this._io, "/types/dna1_body/seq/9");
      }
      this.lengths = new Array(this.numTypes);
      for (var i = 0; i < this.numTypes; i++) {
        this.lengths[i] = this._io.readU2le();
      }
      this.padding3 = this._io.readBytes(KaitaiStream.mod((4 - this._io.pos), 4));
      this.strcMagic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.strcMagic, [83, 84, 82, 67]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([83, 84, 82, 67], this.strcMagic, this._io, "/types/dna1_body/seq/12");
      }
      this.numStructs = this._io.readU4le();
      this.structs = new Array(this.numStructs);
      for (var i = 0; i < this.numStructs; i++) {
        this.structs[i] = new DnaStruct(this._io, this, this._root);
      }
    }

    return Dna1Body;
  })();

  var Header = BlenderBlend.Header = (function() {
    function Header(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    Header.prototype._read = function() {
      this.magic = this._io.readBytes(7);
      if (!((KaitaiStream.byteArrayCompare(this.magic, [66, 76, 69, 78, 68, 69, 82]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([66, 76, 69, 78, 68, 69, 82], this.magic, this._io, "/types/header/seq/0");
      }
      this.ptrSizeId = this._io.readU1();
      this.endian = this._io.readU1();
      this.version = KaitaiStream.bytesToStr(this._io.readBytes(3), "ASCII");
    }

    /**
     * Number of bytes that a pointer occupies
     */
    Object.defineProperty(Header.prototype, 'psize', {
      get: function() {
        if (this._m_psize !== undefined)
          return this._m_psize;
        this._m_psize = (this.ptrSizeId == BlenderBlend.PtrSize.BITS_64 ? 8 : 4);
        return this._m_psize;
      }
    });

    /**
     * Size of a pointer; all pointers in the file are stored in this format
     */

    /**
     * Type of byte ordering used
     */

    /**
     * Blender version used to save this file
     */

    return Header;
  })();

  var DnaField = BlenderBlend.DnaField = (function() {
    function DnaField(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    DnaField.prototype._read = function() {
      this.idxType = this._io.readU2le();
      this.idxName = this._io.readU2le();
    }
    Object.defineProperty(DnaField.prototype, 'type', {
      get: function() {
        if (this._m_type !== undefined)
          return this._m_type;
        this._m_type = this._parent._parent.types[this.idxType];
        return this._m_type;
      }
    });
    Object.defineProperty(DnaField.prototype, 'name', {
      get: function() {
        if (this._m_name !== undefined)
          return this._m_name;
        this._m_name = this._parent._parent.names[this.idxName];
        return this._m_name;
      }
    });

    return DnaField;
  })();
  Object.defineProperty(BlenderBlend.prototype, 'sdnaStructs', {
    get: function() {
      if (this._m_sdnaStructs !== undefined)
        return this._m_sdnaStructs;
      this._m_sdnaStructs = this.blocks[(this.blocks.length - 2)].body.structs;
      return this._m_sdnaStructs;
    }
  });

  return BlenderBlend;
})();
return BlenderBlend;
}));