diff --git a/application/sources/document_window.cc b/application/sources/document_window.cc
index 311095e8..03b02acb 100644
--- a/application/sources/document_window.cc
+++ b/application/sources/document_window.cc
@@ -706,13 +706,15 @@ DocumentWindow::DocumentWindow()
 
 void DocumentWindow::updateInprogressIndicator()
 {
-    if (m_document->isMeshGenerating() ||
-            m_document->isPostProcessing() ||
-            m_document->isTextureGenerating()) {
-        m_inprogressIndicator->showSpinner(true);
-    } else {
-        m_inprogressIndicator->showSpinner(false);
-    }
+    bool inprogress = m_document->isMeshGenerating() ||
+        m_document->isPostProcessing() ||
+        m_document->isTextureGenerating() ||
+        nullptr != m_componentPreviewImagesGenerator ||
+        nullptr != m_componentPreviewImagesDecorator;
+    if (inprogress == m_inprogressIndicator->isSpinning())
+        return;
+    m_inprogressIndicator->showSpinner(inprogress);
+    emit workingStatusChanged(inprogress);
 }
 
 void DocumentWindow::toggleRotation()
@@ -1211,6 +1213,8 @@ void DocumentWindow::generateComponentPreviewImages()
     connect(m_componentPreviewImagesGenerator, &MeshPreviewImagesGenerator::finished, thread, &QThread::quit);
     connect(thread, &QThread::finished, thread, &QThread::deleteLater);
     thread->start();
+
+    updateInprogressIndicator();
 }
 
 void DocumentWindow::componentPreviewImagesReady()
@@ -1230,6 +1234,8 @@ void DocumentWindow::componentPreviewImagesReady()
     
     if (m_isComponentPreviewImagesObsolete)
         generateComponentPreviewImages();
+    else
+        updateInprogressIndicator();
 }
 
 void DocumentWindow::decorateComponentPreviewImages()
@@ -1263,6 +1269,8 @@ void DocumentWindow::decorateComponentPreviewImages()
     connect(m_componentPreviewImagesDecorator.get(), &ComponentPreviewImagesDecorator::finished, thread, &QThread::quit);
     connect(thread, &QThread::finished, thread, &QThread::deleteLater);
     thread->start();
+
+    updateInprogressIndicator();
 }
 
 void DocumentWindow::componentPreviewImageDecorationsReady()
@@ -1280,6 +1288,8 @@ void DocumentWindow::componentPreviewImageDecorationsReady()
     
     if (m_isComponentPreviewImageDecorationsObsolete)
         decorateComponentPreviewImages();
+    else
+        updateInprogressIndicator();
 }
 
 ModelWidget *DocumentWindow::modelWidget()
@@ -1394,4 +1404,9 @@ void DocumentWindow::updateRecentFileActions()
 QString DocumentWindow::strippedName(const QString &fullFileName)
 {
     return QFileInfo(fullFileName).fileName();
-}
\ No newline at end of file
+}
+
+bool DocumentWindow::isWorking()
+{
+    return nullptr == m_inprogressIndicator || m_inprogressIndicator->isSpinning();
+}
diff --git a/application/sources/document_window.h b/application/sources/document_window.h
index 1376a437..d6ca8d03 100644
--- a/application/sources/document_window.h
+++ b/application/sources/document_window.h
@@ -30,11 +30,13 @@ signals:
     void initialized();
     void uninialized();
     void waitingExportFinished(const QString &filename, bool isSuccessful);
+    void workingStatusChanged(bool isWorking);
 public:
     DocumentWindow();
     ~DocumentWindow();
     Document *document();
     ModelWidget *modelWidget();
+    bool isWorking();
     static DocumentWindow *createDocumentWindow();
     static const std::map<DocumentWindow *, dust3d::Uuid> &documentWindows();
     static void showAcknowlegements();
diff --git a/application/sources/main.cc b/application/sources/main.cc
index 60b06c61..8abd9fca 100644
--- a/application/sources/main.cc
+++ b/application/sources/main.cc
@@ -4,6 +4,7 @@
 #include <iostream>
 #include <cstdio>
 #include "document_window.h"
+#include "document.h"
 #include "theme.h"
 #include "version.h"
 
@@ -25,7 +26,81 @@ int main(int argc, char *argv[])
     //freopen("dust3d.log", "w", stdout);
     //setvbuf(stdout, 0, _IONBF, 0);
     
-    DocumentWindow::createDocumentWindow();
+    DocumentWindow *firstWindow = DocumentWindow::createDocumentWindow();
+
+    QStringList openFileList;
+    QStringList waitingExportList;
+    for (int i = 1; i < argc; ++i) {
+        if ('-' == argv[i][0]) {
+            if (0 == strcmp(argv[i], "-output") ||
+                    0 == strcmp(argv[i], "-o")) {
+                ++i;
+                if (i < argc)
+                    waitingExportList.append(argv[i]);
+                continue;
+            }
+            qDebug() << "Unknown option:" << argv[i];
+            continue;
+        }
+        QString arg = argv[i];
+        if (arg.endsWith(".ds3")) {
+            openFileList.append(arg);
+            continue;
+        }
+    }
+    
+    int finishedExportFileNum = 0;
+    int totalExportFileNum = 0;
+    int succeedExportNum = 0;
+    int exitCode = -1;
+    std::vector<DocumentWindow *> windowList;
+    auto checkToSafelyExit = [&]() {
+        if (-1 == exitCode)
+            return;
+        for (int i = 0; i < openFileList.size(); ++i) {
+            if (windowList[i]->isWorking())
+                return;
+        }
+        app.exit(exitCode);
+    };
+    if (!openFileList.empty()) {
+        windowList.push_back(firstWindow);
+        for (int i = 1; i < openFileList.size(); ++i) {
+            windowList.push_back(DocumentWindow::createDocumentWindow());
+        }
+        if (!waitingExportList.empty() &&
+                openFileList.size() == 1) {
+            totalExportFileNum = openFileList.size() * waitingExportList.size();
+            for (int i = 0; i < openFileList.size(); ++i) {
+                QObject::connect(windowList[i], &DocumentWindow::workingStatusChanged, &app, checkToSafelyExit);
+            }
+            for (int i = 0; i < openFileList.size(); ++i) {
+                QObject::connect(windowList[i], &DocumentWindow::waitingExportFinished, &app, [&](const QString &filename, bool isSuccessful) {
+                    qDebug() << "Export to" << filename << (isSuccessful ? "isSuccessful" : "failed");
+                    ++finishedExportFileNum;
+                    if (isSuccessful)
+                        ++succeedExportNum;
+                    if (finishedExportFileNum == totalExportFileNum) {
+                        if (succeedExportNum == totalExportFileNum) {
+                            exitCode = 0;
+                            checkToSafelyExit();
+                            return;
+                        }
+                        exitCode = 1;
+                        checkToSafelyExit();
+                        return;
+                    }
+                });
+            }
+            for (int i = 0; i < openFileList.size(); ++i) {
+                QObject::connect(windowList[i]->document(), &Document::exportReady, windowList[i], &DocumentWindow::checkExportWaitingList);
+                windowList[i]->setExportWaitingList(waitingExportList);
+            }
+        }
+        for (int i = 0; i < openFileList.size(); ++i) {
+            windowList[i]->openPathAs(openFileList[i], openFileList[i]);
+        }
+    }
     
     return app.exec();
 }
diff --git a/application/sources/model_mesh.h b/application/sources/model_mesh.h
index 044b9c82..e8962334 100644
--- a/application/sources/model_mesh.h
+++ b/application/sources/model_mesh.h
@@ -18,7 +18,7 @@ public:
         const std::vector<std::vector<dust3d::Vector3>> &triangleVertexNormals,
         const dust3d::Color &color=dust3d::Color::createWhite(),
         float metalness=0.0,
-        float roughness=0.0,
+        float roughness=1.0,
         const std::vector<std::tuple<dust3d::Color, float/*metalness*/, float/*roughness*/>> *vertexProperties=nullptr);
     ModelMesh(dust3d::Object &object);
     ModelMesh(ModelOpenGLVertex *triangleVertices, int vertexNum);