Open Inventor中SoWriteAction扩展

The following example shows the basic outline on how to set up your own extension action class:

  // This is sample code on how you can get progress indication on Coin
  // export operations by extending the library with your own action
  // class. The new class inherits SoWriteAction. The code is presented
  // as a stand-alone example.
  //
  // The general technique is to inherit SoWriteAction and override it's
  // "entry point" into each node of the scenegraph. The granularity of
  // the progress callbacks is on a per-node basis, which should usually
  // be good enough.

  #include <Inventor/SoDB.h>
  #include <Inventor/actions/SoWriteAction.h>
  #include <Inventor/nodes/SoSeparator.h>



  class MyWriteAction : public SoWriteAction {
    SO_ACTION_HEADER(SoWriteAction);

  public:
    MyWriteAction(SoOutput * out);
    virtual ~MyWriteAction();

    static void initClass(void);

  protected:
    virtual void beginTraversal(SoNode * node);

  private:
    static void actionMethod(SoAction *, SoNode *);
    int nrnodes;
    int totalnrnodes;
  };


  SO_ACTION_SOURCE(MyWriteAction);

  MyWriteAction::MyWriteAction(SoOutput * out)
    : SoWriteAction(out)
  {
    SO_ACTION_CONSTRUCTOR(MyWriteAction);
  }

  MyWriteAction::~MyWriteAction()
  {
  }

  void
  MyWriteAction::initClass(void)
  {
    SO_ACTION_INIT_CLASS(MyWriteAction, SoWriteAction);

    SO_ACTION_ADD_METHOD(SoNode, MyWriteAction::actionMethod);
  }

  void
  MyWriteAction::beginTraversal(SoNode * node)
  {
    this->nrnodes = 0;
    this->totalnrnodes = 0;
    SoWriteAction::beginTraversal(node);
  }

  void
  MyWriteAction::actionMethod(SoAction * a, SoNode * n)
  {
    // To abort the export process in mid-writing, we could just avoid
    // calling in to the SoNode::writeS() method.
    SoNode::writeS(a, n);

    MyWriteAction * mwa = (MyWriteAction *)a;
    SoOutput * out = mwa->getOutput();
    if (out->getStage() == SoOutput::COUNT_REFS) {
      mwa->totalnrnodes++;
    }
    else { //  (out->getStage() == SoOutput::WRITE)
      mwa->nrnodes++;
      SbString s;
      s.sprintf(" # wrote node %p (%d/%d) /n", n, mwa->nrnodes, mwa->totalnrnodes);
      out->write(s.getString());
    }
  }


  int
  main(int argc, char ** argv)
  {
    if (argc < 2) {
      (void)fprintf(stderr, "/n/nUsage: %s <filename>/n/n", argv[0]);
      exit(1);
    }

    SoDB::init();
    MyWriteAction::initClass();

    SoInput in;
    if (!in.openFile(argv[1])) { exit(1); }

    SoSeparator * root = SoDB::readAll(&in);
    if (!root) { exit(1); }

    root->ref();

    SoOutput out;
    MyWriteAction mwa(&out);
    mwa.apply(root);

    root->unref();

    return 0;
  }