scripts/modules/bpy_hydra.py

@@ -100,25 +100,19 @@ class HydraRenderEngine(bpy.types.RenderEngine):
         _bpy_hydra.engine_view_draw(self.engine_ptr, depsgraph.as_pointer(), context.as_pointer())
 
 
-def export_mtlx(material):
+def export_mtlx(material, mtlx_file):
     """ Exports material to .mtlx file. It is called from Blender source code. """
     try:
         import materialx.utils as mx_utils
-
-        doc = mx_utils.export(material, None)
-        if not doc:
-            return ""
-
-        mtlx_file = mx_utils.get_temp_file(".mtlx", material.name)
-        mx_utils.export_to_file(doc, mtlx_file, export_deps=True, copy_deps=False)
-        return str(mtlx_file)
-
     except ImportError:
         print("ERROR: no MaterialX addon available")
+        return False
 
-    except:
-        # This is a placeholder, this code will be moved to C part later
-        # This code shouldn't raise any exception due to breaking refcounts on RenderEngine
-        traceback.print_exc()
+    raise TypeError("asasfas")
+    
+    doc = mx_utils.export(material, None)
+    if not doc:
+        return False
 
-    return ""
+    mx_utils.export_to_file(doc, mtlx_file, export_deps=True, copy_deps=False)
+    return True

source/blender/render/hydra/scene_delegate/material.cc

@@ -17,6 +17,7 @@
 #include "blender_scene_delegate.h"
 #include "material.h"
 #include "mtlx_hydra_adapter.h"
+#include "../utils.h"
 
 namespace blender::render::hydra {
 
@@ -65,25 +66,42 @@ void MaterialData::init()
   RNA_pointer_create(NULL, &RNA_Material, id_, &materialptr);
   PyObject *material = pyrna_struct_CreatePyObject(&materialptr);
 
-  result = PyObject_CallFunction(func, "O", material);
+  char file_name[32];
+  snprintf(file_name, 32, "mat_%016llx.mtlx", (uintptr_t)id_);
+  std::string file_path = temp_file_path(file_name);
+  result = PyObject_CallFunction(func, "Os", material, file_path.c_str());
 
   Py_DECREF(material);
 
-  std::string path;
-
-  if (!PyErr_Occurred()) {
-    path = PyUnicode_AsUTF8(result);
+ if (!PyErr_Occurred()) {
+    if (!PyObject_IsTrue(result)) {
+      file_path = "";
+    }
     Py_DECREF(result);
   }
   else {
-    CLOG_ERROR(LOG_BSD, "Export error for %s", id_->name);
-    PyErr_Print();
+    file_path = "";
+    std::string err_str;
+
+    /* Clearing exception data */
+    PyObject *type, *value, *traceback;
+    PyErr_Fetch(&type, &value, &traceback);
+    if (value) {
+      PyObject *pstr = PyObject_Str(value);
+      err_str = PyUnicode_AsUTF8(pstr);
+      Py_DECREF(pstr);
+    }
+    Py_XDECREF(traceback);
+    Py_XDECREF(value);
+    Py_DECREF(type);
+
+    CLOG_ERROR(LOG_BSD, "Export error for %s (%s): %s", p_id_.GetText(), id_->name, err_str.c_str());
   }
   Py_DECREF(module);
 
   PyGILState_Release(gstate);
 
-  mtlx_path_ = pxr::SdfAssetPath(path, path);
+  mtlx_path_ = pxr::SdfAssetPath(file_path, file_path);
   ID_LOG(2, "mtlx=%s", mtlx_path_.GetResolvedPath().c_str());
 }
 

source/blender/render/hydra/utils.cc

@@ -99,4 +99,11 @@ std::string cache_image(Main *bmain,
   return tempfile;
 }
 
+std::string temp_file_path(std::string const &file_name)
+{
+  char tempfile[FILE_MAX];
+  BLI_path_join(tempfile, sizeof(tempfile), BKE_tempdir_session(), "render_hydra", file_name.c_str());
+  return tempfile;
+}
+
 }  // namespace blender::render::hydra

source/blender/render/hydra/utils.h

@@ -21,5 +21,6 @@ std::string cache_image(Main *bmain,
                         ImageUser *iuser,
                         ImageSaveOptions *opts,
                         ReportList *reports);
+std::string temp_file_path(std::string const &file_name);
 
 }  // namespace blender::render::hydra