White_dune developer documentation

"white_dune", what's that ?

"white_dune" is a continuation of the "dune" project by Stephan F. White.
"dune" is a graphical VRML97/X3D Editor, simple NURBS modeller and animation tool with some OpenGL scene rendering capabilities.

white_dune program overview

In princple, the structure of the white_dune program can be written as:

  1. evaluate commandline parameters
  2. enter GUI (Grapical User Interface) mainloop
For details, see the file main.cpp

white_dune GUI overview

The GUI of white_dune consists of 2 parts:

  1. 2D GUI
    This handles two dimensional operations like opening windows, display icons, menus, buttons etc.
    2D GUI operations are seperated in a extra programming level, called swt (Stephan White Toolkit).
    Currently, there are two different implementations of swt written in C, one for Motif/Lesstif (Unix/Linux) and one for Win32 (M$Windows).
    For details, see the directory swt. swt use M$Windows rc files. For details about the implementation on M$Windows machines see the directory swt/rc.
  2. 3D GUI
    This handles three dimensional operations. This is displaying 3D data (rendering, implemented in OpenGL) and manipulating 3D Objects.
    Some 3D operations, like mouseinput and reaction to desktop events (e.g. resize of Windows) are handled in connection with the 2D GUI (see the file Scene3DView.cpp for details).
    Additional, there are other sources of information for manipulating 3D Objects (also handled in Scene3DView.cpp): input from devices like joystick, dialbox or spaceball. Code for input from this devices is located in the file InputDevice.cpp.

The 2D GUI mainloop of white_dune is event driven. Typical events are mouse-movement, mouse-click, resize of window and so on.
Additionally the mainloop can produce timer events.
When a event occures, the matching callback function is started. The callbacks work for every subwindow of white_dune.
The following image shows the subwindows (red text) of the mainwindow.

subwindows of the mainwindow

Some 2D GUI events are distributed to the different subwindows. The distribution of this events is based on inheritance.
The class SceneView define inheritable 2D GUI callbacks like OnMouseMove and is parent class to the classes ChannelView, FieldView, Scene3DView, SceneGraphView, SceneTreeView, StatusBar, ToolbarWindow and PanedWindow. PanedWindow is parent class to the class MainWindow.

A additional callback OnUpdate is used to distribute messages like UPDATE_FIELD or UPDATE_ADD_NODE to the child classes of SceneView. OnUpdate is started by the function UpdateViews of class Scene.

Some operations require additional input of data. Then a "Dialog" is opened, that block the data input to all other windows.

a example of a dialog

*Dialog classes are all inheritable from the class Dialog, which implements functions like SaveData() and Validate().
The layout of Dialogs (as well as the layout of the menues) is defined in the dune*.rc files.

VRML/X3D implementation overview

The class Scene (Scene.h/cpp) can be identified with one VRML/X3D file. For example Scene.write() writes the VRML/X3D file to disk.

The global variable TheApp of class DuneApp (DuneApp.h/cpp) can be identified with things that are global to all VRML/X3D files.

Node overfield

The internals of each VRML/X3D Node are implemented in the files named NodeNodeName (for example NodeTransform (NodeTransform.h/cpp), NodeShape (NodeShape.h/cpp) or NodeBox (NodeBox.h/cpp)).

Every NodeNodeName.h file contain 2 classes: the class NodeNodeName which contain functionality like draw() for 3D rendering of shapes and the class ProtoNodeName which are used to build the definitions of the VRML97 standard.
For example, the definiton of the Transform Node in the ISO/IEC 14772 standard
example from vrml standard
is implemented in the constructor of the class ProtoTransform (in file NodeTransform.cpp):

ProtoTransform::ProtoTransform(Scene *scene)
  : Proto(scene, "Transform")
    addEventIn(MFNODE, "addChildren");
    addEventIn(MFNODE, "removeChildren");
    center.set(addExposedField(SFVEC3F, "center", new SFVec3f(0.0f, 0.0f, 0.0f)));
    children.set (addExposedField(MFNODE, "children", new MFNode(), CHILD_NODE));
    rotation.set(addExposedField(SFROTATION, "rotation", new SFRotation(0.0f, 0.0f, 1.0f, 0.0f)));
    scale.set(addExposedField(SFVEC3F, "scale", new SFVec3f(1.0f, 1.0f, 1.0f), new SFFloat(0.0f)));
    scaleOrientation.set(addExposedField(SFROTATION, "scaleOrientation",new SFRotation(0.0f, 0.0f, 1.0f, 0.0f)));
    translation.set(addExposedField(SFVEC3F, "translation", new SFVec3f(0.0f, 0.0f, 0.0f)));
    bboxCenter.set(addField(SFVEC3F, "bboxCenter", new SFVec3f(0, 0, 0)));
    bboxSize.set(addField(SFVEC3F, "bboxSize", new SFVec3f(-1, -1, -1), new SFFloat(-1.0f)));
Different fields are internally handled as integer values.
The variables center, children, rotation, scale, scaleOrientation, translation, bboxCenter and bboxSize are of type "fieldIndex", something like a readonly integer, that can be only set once.
There are NodeTransform memberfunctions to get and set field values. For example, the memberfunctions for the field "center" of class "NodeTransform" are:

SFVec3fcenter (void)
void center (SFVec3f *value)
void center (SFVec3f &value)
int center_Field (void)

The memberfunctions "something_Field()" deliver the integer number of a field that is needed for example for a MoveCommand to move nodes in the scenegraph.

Functionality common to all Nodes (like writing a Node to a file (Node.write()) is in the class Node (file Node.h/cpp). All NodeNodeName classes are subclasses of the class Node.
Some of the memberfunctions of the class Node are virtual and can be overwritten by the NodeNodeName classes (for example, the class NodeScript need a special version of Node.write()).
Here is a list of important virtual Node memberfunctions:

Some geometry nodes (like ElevationGrid) are implemented as a subclass of MeshBasedNode. The MeshBasedNode class is used for geometry that can implemented as a IndexedFaceSet type of mesh. The MeshBasedNode class provides important virtual Node memberfunctions like draw. The creation of the mesh in a MeshBasedNode is done via the virtual function createMesh.
Some geometry nodes (like NodeSuperShape) are implemented as a subclass of MeshMorphingNode which is a subclass of MeshBasedNode by itself. A MeshMorphingNode can write a morphing animation of a IndexedFaceSet, when "File->Export As...->Export as &Pure VRML97..." or "File->Export As...->Export as VRML level &X3DV..." is used.
For templates of a MeshBased/MeshMorphing geometry node see NodeGeometryExample.cpp/ NodeGeometryExample.h.
For templates for the rest of nodes see NodeExample.cpp/ NodeExample.h.

FieldValue overfield

The class "FieldValue" is used to set the data of the nodes. The wellknown VRML/X3D types like SFFloat, MFVec3f, SFString etc. are subclasses of the "FieldValue" class.
When setting data of the nodes, it is important that the old data is always deallocated using the "delete" command.
The constructor of "MF-type" data (like MFVec3f, MFInt32, MFString etc.) never copy the data array, it reuses the data via a pointer.
Therefore it is not possible to use "automatic" variables (like "float data[30]") to initalise MF-type data directly. When the automatic variable is removed from the memory, the data inside the node is also lost and it is likely, that a crash would occure.
Wrong example:

       float data[20];
       MFFloat data4node = new MFFloat(data, 20);
       someNode->setField(fieldName_Field(), data4node);
   } // someNode.fieldName gets invalid cause memory is freed at this point
A other example of automatic variable usage uses a internal white_dune data type like "array", "list" etc.:
       Array data;
       MFFloat data4node = new MFFloat(data.getData(), data.size());
       someNode->setField(fieldName_Field(), data4node);
   } // someNode.fieldName gets invalid cause memory is freed at this point
The correct way uses "new"
       float* data = new float[20];
       MFFloat data4node = new MFFloat(data, 20);
       someNode->setField(fieldName_Field(), data4node);
   } // someNode.fieldName ok

Path overview

As Path is a class that holds the path to a node in the Scenegraph or in a PROTO. The path in the Scenegraph is mainly a integer array of the fields containing the SFNode or MFNode field of the next node (one integer) and the index of the next MFNode field (or 0 in case of a SNode field) (another integer).
If path[0] is less than zero, the path is inside a PROTO. A path[0] == -1 is inside the first PROTO, a path[0] == -2 is inside the second proto, a path[0] == -3 is inside the third PROTO etc.
In case of a PROTO, path[1] contains the number of the root node of the PROTO: path[1] == 0 is the path beginning with the first root node, path[1] == 1 is the path beginning with the second root node, path[1] == 2 is the path beginning with the third root node.

PROTO overview

Proto is the PROTO interface (ProtoDeclare or ExternProtoDeclare) or Node interface. Node::getProto() gets the node interface.
NodePROTO is a ProtoInstance or ExternProtoInstance. ExternProtoDeclare is a ProtoDeclare with variable "url" set.

VRML97/X3D parser

Dune need to read and parse ("understand") VRML97 or X3DV files.
This is done with using the tools lex/yacc (it looks like, the advanced tools flex and bison from the GNU project are needed).
The file lexer.l do the lexical analysis (detect things like "what is a string", "what is a number", "what is that VRML97 or X3D keyword").
The file parser.y do the grammatical analysis (detect and prove, if the tokens found by the lexical analysis form valid VRML/X3DV contructions (like Node or ROUTE statements). If some tokens of the grammar are valid, the action part of the command in the parser.y file create the matching VRML Nodes, Numbers etc.

Thanks to Doug Sanden, white_dune can also parse XML encoded X3D files. This is done via the expat library.

Dangerous constructs

The buildin stringtype ("MyString") can be misleading, it act very pointerlike. For example be carefull about constructs like the following:

  MyString str = node->getProto()->getName();
  str += "something";                         // also appended to the name... 
This do not only copy the name of a Proto of "node" to str and append "something" to it, it also appends "something" to the name of a Proto !

In this situation, it is better to use something like
  MyString str = strdup(node->getProto()->getName());
  str += "something"; 
  MyString str = "";
  str += node->getProto()->getName();
  str += "something"; 

Another dangerous constructs are the constructors for MF* types with pointers to multiple data of the basic datatype. This is already described in a chapter above.

"Adding a new node to white_dune"-cookbook

Open Wonderland export

White_dune is able to write the VRML97/X3D scenegraph data in the programming languages C, C++ and java. The resulting data can be used in other programs, e.g. to render the data with a own OpenGL program. There are a lot of visable nodes in VRML97/X3D, so there is away to convert primitive (e.g. Box) or parametric (e.g. NurbsPatchSurface) shapes to mesh data. It is also possible to convert to triangulated mesh data. All visible shapes classes (except shape classes not rendered by white_dune yet and the class of the "Text" node) are children of the MeshBasedNode class, which handles the conversion. Animateable shapes (like Nurbs(Patch)Surface) are children of the MeshMorphingNode class, which is able to create morphing animation data for the resulting mesh data. The MeshMorphingNode class is also a child of the MeshBasedNode class.
White_dune can also directly write the needed java sourcecode to render VRML97/X3D data in the Open Wonderland multiuser server.
This includes features like animation, scripting and interaction.
See the man page of white_dune for more information.
Unfortunatly, there are a lot of nodes, which are not supported by the wonderland exporter. Each node can be written as a java class, but it makes a remarkable difference to the java compiler (with respect to memory usage and compile time) if the classes of the unsupported nodes are written or not. Therefore, the optimization option to avoid unsupported nodes is now per default in use. Unsupported nodes found in the X3D file are also written, but developers who wish to implement the support for such a node may need either always switch off the optimization or mark this node as supported by the Wonderland exporter in the white_dune sources.
The interface of a node is defined in class named e.g. "ProtoSomeNodeName" in the file NodeSomeNodeName.cpp.
The "ProtoSomeNodeName" class is a (direct or indirect) child of a class named "Proto". To mark a node as supported by the Wonderland exporter replace the "Proto" class name in the ProtoSomeNodeName definition

    class SomeNodeName : public Proto {

with the class name "WonderlandExportProto"
    class SomeNodeName : public WonderlandExportProto {

Localisation: translating the program to foreign languages

It requires absolute no programming skills to translate the program to a foreign language, if the foreign languages uses ASCII characters:
you only need to copy the file "src/dune.english.rc" into a similar file, use a texteditor with search and replace und at end translate the strings in this file to the foreign language.

The problems when trying to translate the program to a foreign language with non ASCII characters (like chinease UTF8 characters) are untested/unknown.

To complete the task to create a new runnable program a compatible compiler is needed. Of course, this task can be done (after publicing the main translation file src/dune.something.rc) by a programmer later, it do not need to be done by the translator.
All "src/dune.*.rc" files are copied together into one src/dune.rc file during the run of "configure" and "make".
This means, that for creating a new runnable program, you need either a UNIX like system (e.g. Linux or MacOSX) or a bunch of unixtools:
m4, make, cat, grep and sh (e.g. bash or ksh).
A complete free/opensource installable collection of unixtools for M$Windows is called cygwin and is available for free from the internet.

For Translaton, first search the ISO 3166 two characters of your language (e.g. "en" for english, "de" for german, "it" for italian, etc...) and build the uppercase version of this characters (e.g. EN for english, DE for german, IT for italian, etc).

Second, select a src/dune.something.rc file. In the simpler case, do not select "src/dune.english.rc" cause this requires more complicated search and replace commands.

Third you need to translate all the strings in the new src/dune.something.rc file. A so called string is a term that starts with a " and ends with a "
For example, the translation of the line from src/dune.english.rc

    POPUP "&File"
to german language in src/dune.german.rc would result in
    POPUP "&Datei"
where the german word Datei is the translation of the english word File. The "&" sign marks the keyboard shortcut. The next character after "&" should not be ambient in the same level of a menu.

After the translation of the strings is ready, the translation step is ready. On a Linux/UNIX/MacOSX/cygwin system with the gawk (GNU awk) program you can use

sh test/testmenus.sh
one the commandline to use some consistency testing of the new rc file.

The new file src/dune.something.rc can be now publiced (e.g. in a usenet group like comp.lang.vrml, or at the sourceforge site for the original dune project).

For a recompilation, you first need to extend the list of lanugages, white_dune understands.
Currently you need to extend the list of known languages in the file src/swt/include/languages.m4. E.g. to extend the list of known languages from english (empty default) and german (DE) in src/swt/include/languages.m4

to english, italian (IT) and german, then change the list to
or extent to english, italian and spanish (ES) and german, then change the list to
Take care that the last language line (here with "DE,german") do not end with a comma.

It is also possible to change the yes/no strings in Linux/UNIX messageboxes. E.g. you extend the yes/no strings from english and german in src/swt/include/languages.m4


with the yes/no strings of italian, you have to change src/swt/include/languages.m4 to


The final step is rebuilding the needed files for compilation. On a Linux/UNIX/MacOSX/cygwin system, this is done automatically by using "sh build.sh"
(or "configure && make").
On other systems, at least a text editor and a port of the m4 program is required.
With the texteditor, copy all dune.*.rc files together and store the result in the file "dune.rc"
With m4 you need to execute the following commands in the src directory:

m4 resource.h.m4 > resource.h
m4 CommandlineLanguages.h.m4 > CommandlineLanguages.h

After recompilation (see the file INSTALL for details), the new language can be used with a commandline parameter. The name of the new commandline parameter is the minus sign followed by the second word in the new line in M4_LANGUAGES_CONFIG.
E.g. if you added "IT,italian," to M4_LANGUAGES_CONFIG, the new commandline parameter to switch to the italien language is -italien

All that have to be done now is to add the new commandline parameter to the documentation in the manpage file man/dune.1

Localisation from a programmers point of view

When handling text messages from a programmers point of view, always try to use the function "swLoadString" to get a language related string (e.g. for a errormessage) from the "src/dune.rc" file. The first argument of the swLoadString file is a identifier, like IDS_INTERNAL_ERROR, which refers to the message in the default (english) language. To get the current language translation, add the term TheApp->getLang() to the idenifier, e.g . with swLoadString(IDS_INTERNAL_ERROR + TheApp->getLang(),...

As a programmer, take care about the fact, that each program code modification (e.g. addition of new menu items) in one of the src/dune.something.rc files requires the change of a all other "src/dune.somelanguage.rc" files.
Cause a programmer is usually not a multilingual genius, the addition of a new menuitem, icon tooltip or errormessage comes with a translation problem. There are two possible solutions: either use a dictionary/internet translation service like babelfish.altavista.com, or leave the english word in the src/dune.something.rc file and hope for modification by users.
To leave the line blank cause of a unknown foreign word is not a option, cause this can result in a crash of the program when used in this foreign language.
The addition of a new icon tooltip or errormessage also requires the inclusion of a new "#define" command which can be usually found in the resource.h file.
Do not change the resource.h file directly. The file resource.h is a autogenerated file, that could be overwritten at each run of the "make" command or "configure" command.

class overview

The name of most sourcefiles in the "src" directory is identical to the name of the major contained class.

The following class/filenames have special meanings:

If doxygen is installed, a class hierarchy of white_dune can be produced by typing

         make documentation
and can then be found here.