allow multiple loads of the same file; don't open the Maya API until needed

pandatool/src/mayaegg/mayaApi.cxx

@@ -77,6 +77,8 @@ MayaApi::
 ~MayaApi() {
   nassertv(_global_api == this);
   if (_is_valid) {
+    // Caution!  Calling this function seems to call exit() somewhere
+    // within Maya code.
     MLibrary::cleanup();
   }
   _global_api = (MayaApi *)NULL;
@@ -123,6 +125,21 @@ is_valid() const {
   return _is_valid;
 }
 
+#ifdef WIN32
+static string
+back_to_front_slash(const string &str) {
+  string result = str;
+  string::iterator si;
+  for (si = result.begin(); si != result.end(); ++si) {
+    if ((*si) == '\\') {
+      (*si) = '/';
+    }
+  }
+
+  return result;
+}
+#endif  // WIN32
+
 ////////////////////////////////////////////////////////////////////
 //     Function: MayaApi::read
 //       Access: Public
@@ -136,6 +153,12 @@ read(const Filename &filename) {
   mayaegg_cat.info() << "Reading " << filename << "\n";
   // Load the file into Maya
   string os_filename = filename.to_os_specific();
+
+#ifdef WIN32
+  // Actually, Maya seems to want forward slashes, even on Windows.
+  os_filename = back_to_front_slash(os_filename);
+#endif
+
   MStatus stat = MFileIO::open(os_filename.c_str());
   if (!stat) {
     stat.perror(filename.c_str());

pandatool/src/mayaegg/mayaToEggConverter.cxx

@@ -66,9 +66,9 @@
 ////////////////////////////////////////////////////////////////////
 MayaToEggConverter::
 MayaToEggConverter(const string &program_name) :
-  _shaders(this)
+  _shaders(this),
+  _program_name(program_name)
 {
-  _maya = MayaApi::open_api(program_name);
   _polygon_output = false;
   _polygon_tolerance = 0.01;
   _ignore_transforms = false;
@@ -93,9 +93,7 @@ MayaToEggConverter(const MayaToEggConverter &copy) :
 ////////////////////////////////////////////////////////////////////
 MayaToEggConverter::
 ~MayaToEggConverter() {
-  // We have to clear the shaders before we release the Maya API.
-  _shaders.clear();
-  _maya.clear();
+  close_api();
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -144,7 +142,7 @@ get_extension() const {
 ////////////////////////////////////////////////////////////////////
 bool MayaToEggConverter::
 convert_file(const Filename &filename) {
-  if (!_maya->is_valid()) {
+  if (!open_api()) {
     mayaegg_cat.error()
       << "Maya is not available.\n";
     return false;
@@ -166,6 +164,16 @@ convert_file(const Filename &filename) {
 ////////////////////////////////////////////////////////////////////
 bool MayaToEggConverter::
 convert_maya() {
+  _textures.clear();
+  _shaders.clear();
+  _groups.clear();
+
+  if (!open_api()) {
+    mayaegg_cat.error()
+      << "Maya is not available.\n";
+    return false;
+  }
+
   if (_egg_data->get_coordinate_system() == CS_default) {
     _egg_data->set_coordinate_system(_maya->get_coordinate_system());
   }
@@ -210,6 +218,35 @@ convert_maya() {
   return all_ok;
 }
 
+////////////////////////////////////////////////////////////////////
+//     Function: MayaToEggConverter::open_api
+//       Access: Public
+//  Description: Attempts to open the Maya API if it was not already
+//               open, and returns true if successful, or false if
+//               there is an error.
+////////////////////////////////////////////////////////////////////
+bool MayaToEggConverter::
+open_api() {
+  if (_maya == (MayaApi *)NULL || !_maya->is_valid()) {
+    _maya = MayaApi::open_api(_program_name);
+  }
+  return _maya->is_valid();
+}
+
+////////////////////////////////////////////////////////////////////
+//     Function: MayaToEggConverter::close_api
+//       Access: Public
+//  Description: Closes the Maya API, if it was previously opened.
+//               Caution!  Maya appears to call exit() when its API is
+//               closed.
+////////////////////////////////////////////////////////////////////
+void MayaToEggConverter::
+close_api() {
+  // We have to clear the shaders before we release the Maya API.
+  _shaders.clear();
+  _maya.clear();
+}
+
 ////////////////////////////////////////////////////////////////////
 //     Function: MayaToEggConverter::process_node
 //       Access: Private

pandatool/src/mayaegg/mayaToEggConverter.h

@@ -63,6 +63,9 @@ public:
   virtual bool convert_file(const Filename &filename);
   bool convert_maya();
 
+  bool open_api();
+  void close_api();
+
 private:
   bool process_node(const MDagPath &dag_path, EggData &data);
   void get_transform(const MDagPath &dag_path, EggGroup *egg_group);
@@ -90,6 +93,8 @@ private:
   typedef pmap<string, EggGroup *> Groups;
   Groups _groups;
 
+  string _program_name;
+
 public:
   MayaShaders _shaders;
   EggTextureCollection _textures;

pandatool/src/mayaprogs/mayaToEgg.cxx

@@ -87,7 +87,7 @@ run() {
 
   nout << "Initializing Maya.\n";
   MayaToEggConverter converter(_program_name);
-  if (!converter._maya->is_valid()) {
+  if (!converter.open_api()) {
     nout << "Unable to initialize Maya.\n";
     exit(1);
   }