Posts

• EgorBo BYXamarin Team ✭✭✭

  August 2016

  @EsaKylli.5920 can you please provide a small repro code snippet\project?

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• EsaK SEMember ✭✭

  August 2016

  This is part of my code (in a subclass to Component):

      private Material boxMaterialDefault;
      private Material boxMaterialSelected;
  
      private void CreateMaterials()
      {
          boxMaterialDefault = Application.ResourceCache.GetMaterial("Materials/GameBox.xml");
  
          boxMaterialSelected = boxMaterialDefault.Clone("GameBoxSelected");
          boxMaterialSelected.SetShaderParameter("MatDiffColor", new Color(0.0f, 0.75f, 0.0f, 1.0f));
  
          //boxMaterialSelected = Application.ResourceCache.GetMaterial("Materials/GameBoxSelected.xml");
      }
  

  CreateMaterials() is called when the Application starts. The material is set on my StaticModel via SetMaterial().
  If I comment out the initialization of "boxMaterialSelected", and instead use the commented out line at the end (loading from ResourceCache) it works.

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• EgorBo BYXamarin Team ✭✭✭

  August 2016

  @EsaKylli.5920
  I modified StaticScene sample with this code:

  var mat = cache.GetMaterial("Materials/Mushroom.xml");
  var matCloned = mat.Clone("Clonned");
  matCloned.SetShaderParameter("MatDiffColor", new Color(0.0f, 0.75f, 0.0f, 1.0f));
  
  for (int i = 0; i < 200; i++)
  {
      var mushroom = scene.CreateChild ("Mushroom");
      mushroom.Position = new Vector3 (rand.Next (90)-45, 0, rand.Next (90)-45);
      mushroom.Rotation = new Quaternion (0, rand.Next (360), 0);
      mushroom.SetScale (0.5f+rand.Next (20000)/10000.0f);
      var mushroomObject = mushroom.CreateComponent<StaticModel>();
      mushroomObject.Model = cache.GetModel ("Models/Mushroom.mdl");
      mushroomObject.SetMaterial (i % 2 == 0 ? matCloned : mat);
  }
  

  and it works fine for me (Windows). Can you please create a small repro project?

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• EsaK SEMember ✭✭

  August 2016

  Your above code works fine for me too (on Mac).
  I have isolated the problem now to this specific use-case (modified StaticScene).
  If you left-click once, and then another time you should get a crash.
  The funny thing here is that if you don't use a cloned material (but two different ones loaded from the ResourceCache) it works.
  I have no clue what's going on....

  public class StaticScene : Sample
  {
      Camera camera;
      Scene scene;
  
      public StaticScene(ApplicationOptions options = null) : base(options) { }
  
      protected override void Start()
      {
          base.Start();
          // ** Added
          CreateMaterials();
          //
          CreateScene ();
          SimpleCreateInstructionsWithWasd ();
          SetupViewport ();
      }
  
      void HandleKeyDown(KeyDownEventArgs e)
      {
          switch (e.Key)
          {
              case Key.Esc:
                  Exit();
                  return;
          }
      }
  
      void CreateScene ()
      {
          var cache = ResourceCache;
          scene = new Scene ();
  
          // Create the Octree component to the scene. This is required before adding any drawable components, or else nothing will
          // show up. The default octree volume will be from (-1000, -1000, -1000) to (1000, 1000, 1000) in world coordinates; it
          // is also legal to place objects outside the volume but their visibility can then not be checked in a hierarchically
          // optimizing manner
          scene.CreateComponent<Octree> ();
  
          // Create a child scene node (at world origin) and a StaticModel component into it. Set the StaticModel to show a simple
          // plane mesh with a "stone" material. Note that naming the scene nodes is optional. Scale the scene node larger
          // (100 x 100 world units)
          var planeNode = scene.CreateChild("Plane");
          planeNode.Scale = new Vector3 (100, 1, 100);
          var planeObject = planeNode.CreateComponent<StaticModel> ();
          planeObject.Model = cache.GetModel ("Models/Plane.mdl");
          planeObject.SetMaterial (cache.GetMaterial ("Materials/StoneTiled.xml"));
  
          // Create a directional light to the world so that we can see something. The light scene node's orientation controls the
          // light direction; we will use the SetDirection() function which calculates the orientation from a forward direction vector.
          // The light will use default settings (white light, no shadows)
          var lightNode = scene.CreateChild("DirectionalLight");
          lightNode.SetDirection (new Vector3(0.6f, -1.0f, 0.8f)); // The direction vector does not need to be normalized
          var light = lightNode.CreateComponent<Light>();
          light.LightType = LightType.Directional;
  
          // ** Removed
          /*
          var rand = new Random();
          for (int i = 0; i < 200; i++)
          {
              var mushroom = scene.CreateChild ("Mushroom");
              mushroom.Position = new Vector3 (rand.Next (90)-45, 0, rand.Next (90)-45);
              mushroom.Rotation = new Quaternion (0, rand.Next (360), 0);
              mushroom.SetScale (0.5f+rand.Next (20000)/10000.0f);
              var mushroomObject = mushroom.CreateComponent<StaticModel>();
              mushroomObject.Model = cache.GetModel ("Models/Mushroom.mdl");
              mushroomObject.SetMaterial (cache.GetMaterial ("Materials/Mushroom.xml"));
          }
          */
          //
          CameraNode = scene.CreateChild ("camera");
          camera = CameraNode.CreateComponent<Camera>();
          CameraNode.Position = new Vector3 (0, 5, 0);
      }
  
      void SetupViewport ()
      {
          var renderer = Renderer;
          renderer.SetViewport (0, new Viewport (Context, scene, camera, null));
      }
  
      protected override void OnUpdate(float timeStep)
      {
          base.OnUpdate(timeStep);
          SimpleMoveCamera3D(timeStep);
  
          // ** Added
          var input = Application.Current.Input;
          if (input.GetMouseButtonDown(MouseButton.Left))
          {
              if (selectedNode != null)
              {
                  selectedNodeModel.SetMaterial(originalMaterial);
                  selectedNode = null;
                  selectedNodeModel = null;
              }
              else
              {
                  CreateMushroom(new Vector3(x, 0, 20));
                  x += 1;
              }
          }
          //
      }
  
      // ** Added
      private float x = 0;
      private Node selectedNode;
      private StaticModel selectedNodeModel;
  
      private Material originalMaterial;
      private Material clonedMaterial;
  
      private void CreateMaterials()
      {
          var cache = ResourceCache;
  
          originalMaterial = cache.GetMaterial("Materials/Mushroom.xml");
          clonedMaterial = originalMaterial.Clone("Clonned");
          clonedMaterial.SetShaderParameter("MatDiffColor", new Color(0.0f, 0.0f, 0.75f, 1.0f));
      }
  
      private void CreateMushroom(Vector3 pos)
      {
          var mushroom = scene.CreateChild("Mushroom");
          mushroom.Position = pos;
          mushroom.SetScale(2);
          var mushroomObject = mushroom.CreateComponent<StaticModel>();
          mushroomObject.Model = ResourceCache.GetModel("Models/Mushroom.mdl");
          mushroomObject.SetMaterial(clonedMaterial);
  
          selectedNode = mushroom;
          selectedNodeModel = mushroomObject;
      }
      //
  
  }
  

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• EgorBo BYXamarin Team ✭✭✭

  August 2016 edited August 2016

  @EsaKylli.5920
  The problem is:
  when you replace cloned material with the original one via this code:
  selectedNodeModel.SetMaterial(originalMaterial);
  the inner Urho3D will delete cloned material as nobody uses it anymore (for example, if the scene would have some long-live StaticModel with this cloned material - the bug wouldn't happen).
  Initial SetMaterial(clonedMaterial) incremented inner RefsCount to 1 from 0 and the following operation
  selectedNodeModel.SetMaterial(originalMaterial);
  did ReleasRef over clonedMaterial and since RefCount became 0 - it triggered "delete".

  So as a workaround you can do:
  clonedMaterial = originalMaterial.Clone("Clonned");
  clonedMaterial.AddRef(); //surrogate reference in order to keep it alive

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• EsaK SEMember ✭✭

  August 2016

  That makes sense. I guess it's a consequence when mixing managed (C#) and unmanaged (C++) code?
  (When working with Urho3D in C++ I remember I had to encapsulate the material reference in my class in a SharedPtr.)

  Do I have to add ReleseRef() to it also? When should I do that? Not when exiting the game, isn't it deallocated anyway in that case?

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• EgorBo BYXamarin Team ✭✭✭

  August 2016

  @EsaKylli.5920
  It's a temporary workaround, will be fixed in the next version. As for now, yes, you'll have to call ReleaseRef once you don't need "clonedMaterial" anymore (otherwise it will leak).

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• EsaK SEMember ✭✭

  August 2016

  So what you are saying is that the reference counting will work automatically between managed and unmanaged code (in a coming version)?

  Do I have to call ReleaseRef() even when exiting the game?

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