add nanort lib and update external git modules

.gitmodules

@@ -43,3 +43,6 @@
 [submodule "libs/openvr"]
 	path = libs/openvr
 	url = https://github.com/ValveSoftware/openvr.git
+[submodule "libs/nanort"]
+	path = libs/nanort
+	url = https://github.com/lighttransport/nanort.git

PanoPainter.vcxproj

@@ -112,7 +112,7 @@
       <PrecompiledHeader>Use</PrecompiledHeader>
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>DEBUG;_DEBUG;_CONSOLE;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PrecompiledHeaderFile>pch.h</PrecompiledHeaderFile>
       <ExceptionHandling>false</ExceptionHandling>
     </ClCompile>
@@ -169,6 +169,10 @@
     </PreBuildEvent>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClCompile Include="libs\nanort\nanort.cc">
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">NotUsing</PrecompiledHeader>
+      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
+    </ClCompile>
     <ClCompile Include="libs\sqlite3\sqlite3.c">
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">NotUsing</PrecompiledHeader>
       <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
@@ -300,6 +304,7 @@
     </ClCompile>
   </ItemGroup>
   <ItemGroup>
+    <ClInclude Include="libs\nanort\nanort.h" />
     <ClInclude Include="libs\sqlite3\sqlite3.h" />
     <ClInclude Include="libs\sqlite3\sqlite3ext.h" />
     <ClInclude Include="src\action.h" />

PanoPainter.vcxproj.filters

@@ -43,6 +43,9 @@
     <Filter Include="libs\sqlite3">
       <UniqueIdentifier>{ef44d179-f28b-458c-b3df-be2895553149}</UniqueIdentifier>
     </Filter>
+    <Filter Include="libs\nanort">
+      <UniqueIdentifier>{be0c0053-abd8-4e2d-a294-7c54511b05a6}</UniqueIdentifier>
+    </Filter>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="src\app.cpp">
@@ -276,6 +279,9 @@
     <ClCompile Include="src\app_vr.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="libs\nanort\nanort.cc">
+      <Filter>libs\nanort</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="src\app.h">
@@ -494,6 +500,9 @@
     <ClInclude Include="src\hmd.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="libs\nanort\nanort.h">
+      <Filter>libs\nanort</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="PanoPainter.rc">

src/canvas.cpp

@@ -2207,6 +2207,9 @@ void Canvas::draw_objects(std::function<void(const glm::mat4& camera, const glm:
 
         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 0);
         layer.m_rtt[i].unbindFramebuffer();
+
+        layer.m_dirty_face[i] = true;
+        layer.m_dirty_box[i] = { 0, 0, layer.w, layer.h };
     }
 
     glDeleteRenderbuffers(1, &rboID);

src/node_panel_grid.cpp

@@ -104,7 +104,7 @@ void NodePanelGrid::init_controls()
             auto sz = m_hm_preview->tex.size();
             m_hm_preview->SetAspectRatio(sz.x / sz.y);
             m_hm_plane.create(1, 1, m_hm_image, 
-                m_groud_resolution->get_value() * 5.f, m_hm_height->get_value());
+                m_groud_resolution->get_value() * 5.f, get_height());
             m_hm_preview->SetHeight(100);
         }
     };
@@ -122,7 +122,7 @@ void NodePanelGrid::init_controls()
 
 float NodePanelGrid::get_height() const
 {
-    return glm::pow(m_hm_height->get_value() - 0.5f, 3.f) * 10.f;
+    return -glm::pow(m_hm_height->get_value() - 0.5f, 3.f) * 10.f;
 }
 
 float NodePanelGrid::get_offset() const