Fix race condition when rendering the UI (gazebosim#304)

This fix also depends on on a fix in ign-gazebo so that it now can call
SwapFromThread, otherwise the race condition will still happen.

At the current moment, the implementation is very wasteful creating many
more RenderTargets than needed (because 2 workspaces are created).
This issue will be fixed in the next commit

Affects gazebosim#304

Signed-off-by: Matias N. Goldberg <[email protected]>

include/ignition/rendering/Camera.hh

@@ -279,9 +279,14 @@ namespace ignition
       /// \brief Get the OpenGL texture id associated with the render texture
       /// used by this camera. A valid id is returned only if the underlying
       /// render engine is OpenGL based.
-      /// \return Texture Id of type GLuint.
+      /// \return Texture Id of type GLuint. Returned value is
+      /// valid until the next SwapFromThread() call
       public: virtual unsigned int RenderTextureGLId() const = 0;
 
+      /// \brief Informs this Camera we're done updating from worker thread
+      /// and for this iteration of the loop
+      public: virtual void SwapFromThread() = 0;
+
       /// \brief Add a render pass to the camera
       /// \param[in] _pass New render pass to add
       public: virtual void AddRenderPass(const RenderPassPtr &_pass) = 0;

include/ignition/rendering/RenderTarget.hh

@@ -93,6 +93,10 @@ namespace ignition
       /// \return Render pass at the specified index
       public: virtual RenderPassPtr RenderPassByIndex(unsigned int _index)
           const = 0;
+
+      /// \brief Informs this RenderTarget we're done updating from worker
+      /// thread and for this iteration of the loop
+      public: virtual void SwapFromThread() = 0;
     };
 
     /* \class RenderTexture RenderTexture.hh \

include/ignition/rendering/base/BaseCamera.hh

@@ -164,6 +164,9 @@ namespace ignition
       // Documentation inherited.
       public: virtual unsigned int RenderTextureGLId() const override;
 
+      // Documentation inherited.
+      public: virtual void SwapFromThread() override;
+
       // Documentation inherited.
       public: virtual void AddRenderPass(const RenderPassPtr &_pass) override;
 
@@ -708,6 +711,14 @@ namespace ignition
       return 0u;
     }
 
+    //////////////////////////////////////////////////
+    template <class T>
+    void BaseCamera<T>::SwapFromThread()
+    {
+      ignerr << "SwapFromThread is not supported by current render"
+          << " engine" << std::endl;
+    }
+
     //////////////////////////////////////////////////
     template <class T>
     void BaseCamera<T>::AddRenderPass(const RenderPassPtr &_pass)

include/ignition/rendering/base/BaseRenderTarget.hh

@@ -79,6 +79,9 @@ namespace ignition
 
       protected: virtual void RebuildImpl() = 0;
 
+      // Documentation inherited.
+      public: virtual void SwapFromThread() override;
+
       protected: PixelFormat format = PF_UNKNOWN;
 
       protected: bool targetDirty = true;
@@ -176,6 +179,12 @@ namespace ignition
       }
     }
 
+    //////////////////////////////////////////////////
+    template <class T>
+    void BaseRenderTarget<T>::SwapFromThread()
+    {
+    }
+
     //////////////////////////////////////////////////
     template <class T>
     unsigned int BaseRenderTarget<T>::Width() const

ogre2/include/ignition/rendering/ogre2/Ogre2Camera.hh

@@ -105,6 +105,9 @@ namespace ignition
       // Documentation inherited.
       public: virtual unsigned int RenderTextureGLId() const override;
 
+      // Documentation inherited.
+      public: virtual void SwapFromThread() override;
+
       // Documentation inherited.
       public: virtual void Destroy() override;
 

ogre2/include/ignition/rendering/ogre2/Ogre2RenderTarget.hh

@@ -191,6 +191,9 @@ namespace ignition
       /// into a render target or render texture.
       protected: Ogre::CompositorWorkspace *ogreCompositorWorkspace = nullptr;
 
+      /// \brief See Ogre2RenderTexture::ogreTexture
+      protected: Ogre::CompositorWorkspace *ogreCompositorWorkspaceInDisplay = nullptr;
+
       /// \brief Ogre's compositor workspace definition name
       protected: std::string ogreCompositorWorkspaceDefName;
 
@@ -245,6 +248,9 @@ namespace ignition
       // Documentation inherited
       public: virtual unsigned int GLId() const override;
 
+      // Documentation inherited.
+      public: virtual void SwapFromThread() override;
+
       // Documentation inherited.
       public: virtual Ogre::RenderTarget *RenderTarget() const override;
 
@@ -258,8 +264,12 @@ namespace ignition
       protected: virtual void BuildTarget();
 
       /// \brief Pointer to the internal ogre render texture object
+      /// This value may get swapped with ogreTextureInDisplay
+      /// after calling SwapFromThread
       protected: Ogre::Texture *ogreTexture = nullptr;
 
+      protected: Ogre::Texture *ogreTextureInDisplay = nullptr;
+
       /// \brief Make scene our friend so it can create a ogre2 render texture
       private: friend class Ogre2Scene;
     };

ogre2/src/Ogre2Camera.cc

@@ -207,6 +207,12 @@ unsigned int Ogre2Camera::RenderTextureGLId() const
   return rt->GLId();
 }
 
+//////////////////////////////////////////////////
+void Ogre2Camera::SwapFromThread()
+{
+  this->renderTexture->SwapFromThread();
+}
+
 //////////////////////////////////////////////////
 void Ogre2Camera::SetSelectionBuffer()
 {

ogre2/src/Ogre2RenderTarget.cc

@@ -280,21 +280,30 @@ void Ogre2RenderTarget::BuildCompositor()
 //////////////////////////////////////////////////
 void Ogre2RenderTarget::DestroyCompositor()
 {
-  if (!this->ogreCompositorWorkspace)
+  if (!this->ogreCompositorWorkspace && !this->ogreCompositorWorkspaceInDisplay)
     return;
 
   auto engine = Ogre2RenderEngine::Instance();
   auto ogreRoot = engine->OgreRoot();
   Ogre::CompositorManager2 *ogreCompMgr = ogreRoot->getCompositorManager2();
-  this->ogreCompositorWorkspace->setListener(nullptr);
-  ogreCompMgr->removeWorkspace(this->ogreCompositorWorkspace);
+  if (this->ogreCompositorWorkspace)
+  {
+    this->ogreCompositorWorkspace->setListener(nullptr);
+    ogreCompMgr->removeWorkspace(this->ogreCompositorWorkspace);
+  }
+  if (ogreCompositorWorkspaceInDisplay)
+  {
+    this->ogreCompositorWorkspaceInDisplay->setListener(nullptr);
+    ogreCompMgr->removeWorkspace(this->ogreCompositorWorkspaceInDisplay);
+  }
   ogreCompMgr->removeWorkspaceDefinition(this->ogreCompositorWorkspaceDefName);
   ogreCompMgr->removeNodeDefinition(this->ogreCompositorWorkspaceDefName +
       "/" + this->dataPtr->kBaseNodeName);
-  ogreCompMgr->removeNodeDefinition(this->ogreCompositorWorkspaceDefName +
-      "/" + this->dataPtr->kFinalNodeName);
+  //ogreCompMgr->removeNodeDefinition(this->ogreCompositorWorkspaceDefName +
+  //    "/" + this->dataPtr->kFinalNodeName);
 
   this->ogreCompositorWorkspace = nullptr;
+  this->ogreCompositorWorkspaceInDisplay = nullptr;
   delete this->dataPtr->rtListener;
   this->dataPtr->rtListener = nullptr;
 }
@@ -447,11 +456,23 @@ void Ogre2RenderTarget::UpdateBackgroundColor()
   if (this->colorDirty)
   {
     // set background color in compositor clear pass def
-    auto nodeSeq = this->ogreCompositorWorkspace->getNodeSequence();
-    auto pass = nodeSeq[0]->_getPasses()[0]->getDefinition();
-    auto clearPass = dynamic_cast<const Ogre::CompositorPassClearDef *>(pass);
-    const_cast<Ogre::CompositorPassClearDef *>(clearPass)->mColourValue =
-        this->ogreBackgroundColor;
+    if (this->ogreCompositorWorkspace)
+    {
+      auto nodeSeq = this->ogreCompositorWorkspace->getNodeSequence();
+      auto pass = nodeSeq[0]->_getPasses()[0]->getDefinition();
+      auto clearPass = dynamic_cast<const Ogre::CompositorPassClearDef *>(pass);
+      const_cast<Ogre::CompositorPassClearDef *>(clearPass)->mColourValue =
+          this->ogreBackgroundColor;
+    }
+
+    if (this->ogreCompositorWorkspaceInDisplay)
+    {
+      auto nodeSeq = this->ogreCompositorWorkspaceInDisplay->getNodeSequence();
+      auto pass = nodeSeq[0]->_getPasses()[0]->getDefinition();
+      auto clearPass = dynamic_cast<const Ogre::CompositorPassClearDef *>(pass);
+      const_cast<Ogre::CompositorPassClearDef *>(clearPass)->mColourValue =
+          this->ogreBackgroundColor;
+    }
 
     this->colorDirty = false;
   }
@@ -1074,18 +1095,27 @@ void Ogre2RenderTexture::RebuildTarget()
 //////////////////////////////////////////////////
 void Ogre2RenderTexture::DestroyTarget()
 {
-  if (nullptr == this->ogreTexture)
+  if (nullptr == this->ogreTexture && nullptr == this->ogreTextureInDisplay)
     return;
 
   auto &manager = Ogre::TextureManager::getSingleton();
-  manager.unload(this->ogreTexture->getName());
-  manager.remove(this->ogreTexture->getName());
+  if (this->ogreTexture)
+  {
+    manager.unload(this->ogreTexture->getName());
+    manager.remove(this->ogreTexture->getName());
+  }
+  if (this->ogreTextureInDisplay)
+  {
+    manager.unload(this->ogreTextureInDisplay->getName());
+    manager.remove(this->ogreTextureInDisplay->getName());
+  }
 
   // TODO(anyone) there is memory leak when a render texture is destroyed.
   // The RenderSystem::_cleanupDepthBuffers method used in ogre1 does not
   // seem to work in ogre2
 
   this->ogreTexture = nullptr;
+  this->ogreTextureInDisplay = nullptr;
 }
 
 //////////////////////////////////////////////////
@@ -1115,9 +1145,14 @@ void Ogre2RenderTexture::BuildTarget()
       ogre2FSAAWarn = true;
     }
   }
+  fsaa = 0;
+
+  std::string texNameSuffix;
+  if (this->ogreTextureInDisplay)
+    texNameSuffix += "InDisplay1";
 
   // Ogre 2 PBS expects gamma correction to be enabled
-  this->ogreTexture = (manager.createManual(this->name, "General",
+  this->ogreTexture = (manager.createManual(this->name + texNameSuffix, "General",
       Ogre::TEX_TYPE_2D, this->width, this->height, 0, ogreFormat,
       Ogre::TU_RENDERTARGET, 0, true, fsaa)).get();
 }
@@ -1134,6 +1169,21 @@ unsigned int Ogre2RenderTexture::GLId() const
   return static_cast<unsigned int>(texId);
 }
 
+//////////////////////////////////////////////////
+void Ogre2RenderTexture::SwapFromThread()
+{
+  std::swap( this->ogreCompositorWorkspace, this->ogreCompositorWorkspaceInDisplay );
+  std::swap( this->ogreTexture, this->ogreTextureInDisplay );
+
+  // If this is the first time swapping, we're being aware we're in
+  // different threads, thus initialize the 2nd pair of resources
+  if (!this->ogreTexture && this->ogreTextureInDisplay)
+  {
+    BuildTarget();
+    BuildCompositor();
+  }
+}
+
 //////////////////////////////////////////////////
 void Ogre2RenderTexture::PreRender()
 {