text: //
  // Copyright (c) 2008-2015 the Urho3D project.
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  //
  
  #include <Urho3D/Core/CoreEvents.h>
  #include <Urho3D/Engine/Engine.h>
  #include <Urho3D/Graphics/Camera.h>
  #include <Urho3D/Graphics/DebugRenderer.h>
  #include <Urho3D/Graphics/DecalSet.h>
  #include <Urho3D/Graphics/Graphics.h>
  #include <Urho3D/Graphics/Light.h>
  #include <Urho3D/Graphics/Material.h>
  #include <Urho3D/Graphics/Model.h>
  #include <Urho3D/Graphics/Octree.h>
  #include <Urho3D/Graphics/Renderer.h>
  #include <Urho3D/Graphics/StaticModel.h>
  #include <Urho3D/Graphics/Zone.h>
  #include <Urho3D/Input/Input.h>
  #include <Urho3D/Resource/ResourceCache.h>
  #include <Urho3D/Scene/Scene.h>
  #include <Urho3D/UI/Font.h>
  #include <Urho3D/UI/Text.h>
  #include <Urho3D/UI/UI.h>
  
  #include "Decals.h"
  
  #include <Urho3D/DebugNew.h>
  
  URHO3D_DEFINE_APPLICATION_MAIN(Decals)
  
  Decals::Decals(Context* context) :
      Sample(context),
      drawDebug_(false)
  {
  }
  
  void Decals::Start()
  {
      // Execute base class startup
      Sample::Start();
  
      // Create the scene content
      CreateScene();
  
      // Create the UI content
      CreateUI();
  
      // Setup the viewport for displaying the scene
      SetupViewport();
  
      // Hook up to the frame update and render post-update events
      SubscribeToEvents();
  }
  
  void Decals::CreateScene()
  {
      ResourceCache* cache = GetSubsystem<ResourceCache>();
  
      scene_ = new Scene(context_);
  
      // Create octree, use default volume (-1000, -1000, -1000) to (1000, 1000, 1000)
      // Also create a DebugRenderer component so that we can draw debug geometry
      scene_->CreateComponent<Octree>();
      scene_->CreateComponent<DebugRenderer>();
  
      // Create scene node & StaticModel component for showing a static plane
      Node* planeNode = scene_->CreateChild("Plane");
      planeNode->SetScale(Vector3(100.0f, 1.0f, 100.0f));
      StaticModel* planeObject = planeNode->CreateComponent<StaticModel>();
      planeObject->SetModel(cache->GetResource<Model>("Models/Plane.mdl"));
      planeObject->SetMaterial(cache->GetResource<Material>("Materials/StoneTiled.xml"));
  
      // Create a Zone component for ambient lighting & fog control
      Node* zoneNode = scene_->CreateChild("Zone");
      Zone* zone = zoneNode->CreateComponent<Zone>();
      zone->SetBoundingBox(BoundingBox(-1000.0f, 1000.0f));
      zone->SetAmbientColor(Color(0.15f, 0.15f, 0.15f));
      zone->SetFogColor(Color(0.5f, 0.5f, 0.7f));
      zone->SetFogStart(100.0f);
      zone->SetFogEnd(300.0f);
  
      // Create a directional light to the world. Enable cascaded shadows on it
      Node* lightNode = scene_->CreateChild("DirectionalLight");
      lightNode->SetDirection(Vector3(0.6f, -1.0f, 0.8f));
      Light* light = lightNode->CreateComponent<Light>();
      light->SetLightType(LIGHT_DIRECTIONAL);
      light->SetCastShadows(true);
      light->SetShadowBias(BiasParameters(0.00025f, 0.5f));
      // Set cascade splits at 10, 50 and 200 world units, fade shadows out at 80% of maximum shadow distance
      light->SetShadowCascade(CascadeParameters(10.0f, 50.0f, 200.0f, 0.0f, 0.8f));
  
      // Create some mushrooms
      const unsigned NUM_MUSHROOMS = 240;
      for (unsigned i = 0; i < NUM_MUSHROOMS; ++i)
      {
          Node* mushroomNode = scene_->CreateChild("Mushroom");
          mushroomNode->SetPosition(Vector3(Random(90.0f) - 45.0f, 0.0f, Random(90.0f) - 45.0f));
          mushroomNode->SetRotation(Quaternion(0.0f, Random(360.0f), 0.0f));
          mushroomNode->SetScale(0.5f + Random(2.0f));
          StaticModel* mushroomObject = mushroomNode->CreateComponent<StaticModel>();
          mushroomObject->SetModel(cache->GetResource<Model>("Models/Mushroom.mdl"));
          mushroomObject->SetMaterial(cache->GetResource<Material>("Materials/Mushroom.xml"));
          mushroomObject->SetCastShadows(true);
      }
  
      // Create randomly sized boxes. If boxes are big enough, make them occluders. Occluders will be software rasterized before
      // rendering to a low-resolution depth-only buffer to test the objects in the view frustum for visibility
      const unsigned NUM_BOXES = 20;
      for (unsigned i = 0; i < NUM_BOXES; ++i)
      {
          Node* boxNode = scene_->CreateChild("Box");
          float size = 1.0f + Random(10.0f);
          boxNode->SetPosition(Vector3(Random(80.0f) - 40.0f, size * 0.5f, Random(80.0f) - 40.0f));
          boxNode->SetScale(size);
          StaticModel* boxObject = boxNode->CreateComponent<StaticModel>();
          boxObject->SetModel(cache->GetResource<Model>("Models/Box.mdl"));
          boxObject->SetMaterial(cache->GetResource<Material>("Materials/Stone.xml"));
          boxObject->SetCastShadows(true);
          if (size >= 3.0f)
              boxObject->SetOccluder(true);
      }
  
      // Create the camera. Limit far clip distance to match the fog
      cameraNode_ = scene_->CreateChild("Camera");
      Camera* camera = cameraNode_->CreateComponent<Camera>();
      camera->SetFarClip(300.0f);
  
      // Set an initial position for the camera scene node above the plane
      cameraNode_->SetPosition(Vector3(0.0f, 5.0f, 0.0f));
  }
  
  void Decals::CreateUI()
  {
      ResourceCache* cache = GetSubsystem<ResourceCache>();
      UI* ui = GetSubsystem<UI>();
  
      // Create a Cursor UI element because we want to be able to hide and show it at will. When hidden, the mouse cursor will
      // control the camera, and when visible, it will point the raycast target
      XMLFile* style = cache->GetResource<XMLFile>("UI/DefaultStyle.xml");
      SharedPtr<Cursor> cursor(new Cursor(context_));
      cursor->SetStyleAuto(style);
      ui->SetCursor(cursor);
      // Set starting position of the cursor at the rendering window center
      Graphics* graphics = GetSubsystem<Graphics>();
      cursor->SetPosition(graphics->GetWidth() / 2, graphics->GetHeight() / 2);
  
      // Construct new Text object, set string to display and font to use
      Text* instructionText = ui->GetRoot()->CreateChild<Text>();
      instructionText->SetText(
          "Use WASD keys to move\n"
          "LMB to paint decals, RMB to rotate view\n"
          "Space to toggle debug geometry\n"
          "7 to toggle occlusion culling"
      );
      instructionText->SetFont(cache->GetResource<Font>("Fonts/Anonymous Pro.ttf"), 15);
      // The text has multiple rows. Center them in relation to each other
      instructionText->SetTextAlignment(HA_CENTER);
  
      // Position the text relative to the screen center
      instructionText->SetHorizontalAlignment(HA_CENTER);
      instructionText->SetVerticalAlignment(VA_CENTER);
      instructionText->SetPosition(0, ui->GetRoot()->GetHeight() / 4);
  }
  
  void Decals::SetupViewport()
  {
      Renderer* renderer = GetSubsystem<Renderer>();
  
      // Set up a viewport to the Renderer subsystem so that the 3D scene can be seen
      SharedPtr<Viewport> viewport(new Viewport(context_, scene_, cameraNode_->GetComponent<Camera>()));
      renderer->SetViewport(0, viewport);
  }
  
  void Decals::SubscribeToEvents()
  {
      // Subscribe HandleUpdate() function for processing update events
      SubscribeToEvent(E_UPDATE, URHO3D_HANDLER(Decals, HandleUpdate));
  
      // Subscribe HandlePostRenderUpdate() function for processing the post-render update event, during which we request
      // debug geometry
      SubscribeToEvent(E_POSTRENDERUPDATE, URHO3D_HANDLER(Decals, HandlePostRenderUpdate));
  }
  
  void Decals::MoveCamera(float timeStep)
  {
      // Right mouse button controls mouse cursor visibility: hide when pressed
      UI* ui = GetSubsystem<UI>();
      Input* input = GetSubsystem<Input>();
      ui->GetCursor()->SetVisible(!input->GetMouseButtonDown(MOUSEB_RIGHT));
  
      // Do not move if the UI has a focused element (the console)
      if (ui->GetFocusElement())
          return;
  
      // Movement speed as world units per second
      const float MOVE_SPEED = 20.0f;
      // Mouse sensitivity as degrees per pixel
      const float MOUSE_SENSITIVITY = 0.1f;
  
      // Use this frame's mouse motion to adjust camera node yaw and pitch. Clamp the pitch between -90 and 90 degrees
      // Only move the camera when the cursor is hidden
      if (!ui->GetCursor()->IsVisible())
      {
          IntVector2 mouseMove = input->GetMouseMove();
          yaw_ += MOUSE_SENSITIVITY * mouseMove.x_;
          pitch_ += MOUSE_SENSITIVITY * mouseMove.y_;
          pitch_ = Clamp(pitch_, -90.0f, 90.0f);
  
          // Construct new orientation for the camera scene node from yaw and pitch. Roll is fixed to zero
          cameraNode_->SetRotation(Quaternion(pitch_, yaw_, 0.0f));
      }
  
      // Read WASD keys and move the camera scene node to the corresponding direction if they are pressed
      if (input->GetKeyDown('W'))
          cameraNode_->Translate(Vector3::FORWARD * MOVE_SPEED * timeStep);
      if (input->GetKeyDown('S'))
          cameraNode_->Translate(Vector3::BACK * MOVE_SPEED * timeStep);
      if (input->GetKeyDown('A'))
          cameraNode_->Translate(Vector3::LEFT * MOVE_SPEED * timeStep);
      if (input->GetKeyDown('D'))
          cameraNode_->Translate(Vector3::RIGHT * MOVE_SPEED * timeStep);
  
      // Toggle debug geometry with space
      if (input->GetKeyPress(KEY_SPACE))
          drawDebug_ = !drawDebug_;
  
      // Paint decal with the left mousebutton; cursor must be visible
      if (ui->GetCursor()->IsVisible() && input->GetMouseButtonPress(MOUSEB_LEFT))
          PaintDecal();
  }
  
  void Decals::PaintDecal()
  {
      Vector3 hitPos;
      Drawable* hitDrawable;
  
      if (Raycast(250.0f, hitPos, hitDrawable))
      {
          // Check if target scene node already has a DecalSet component. If not, create now
          Node* targetNode = hitDrawable->GetNode();
          DecalSet* decal = targetNode->GetComponent<DecalSet>();
          if (!decal)
          {
              ResourceCache* cache = GetSubsystem<ResourceCache>();
  
              decal = targetNode->CreateComponent<DecalSet>();
              decal->SetMaterial(cache->GetResource<Material>("Materials/UrhoDecal.xml"));
          }
          // Add a square decal to the decal set using the geometry of the drawable that was hit, orient it to face the camera,
          // use full texture UV's (0,0) to (1,1). Note that if we create several decals to a large object (such as the ground
          // plane) over a large area using just one DecalSet component, the decals will all be culled as one unit. If that is
          // undesirable, it may be necessary to create more than one DecalSet based on the distance
          decal->AddDecal(hitDrawable, hitPos, cameraNode_->GetRotation(), 0.5f, 1.0f, 1.0f, Vector2::ZERO,
              Vector2::ONE);
      }
  }
  
  bool Decals::Raycast(float maxDistance, Vector3& hitPos, Drawable*& hitDrawable)
  {
      hitDrawable = 0;
  
      UI* ui = GetSubsystem<UI>();
      IntVector2 pos = ui->GetCursorPosition();
      // Check the cursor is visible and there is no UI element in front of the cursor
      if (!ui->GetCursor()->IsVisible() || ui->GetElementAt(pos, true))
          return false;
  
      Graphics* graphics = GetSubsystem<Graphics>();
      Camera* camera = cameraNode_->GetComponent<Camera>();
      Ray cameraRay = camera->GetScreenRay((float)pos.x_ / graphics->GetWidth(), (float)pos.y_ / graphics->GetHeight());
      // Pick only geometry objects, not eg. zones or lights, only get the first (closest) hit
      PODVector<RayQueryResult> results;
      RayOctreeQuery query(results, cameraRay, RAY_TRIANGLE, maxDistance, DRAWABLE_GEOMETRY);
      scene_->GetComponent<Octree>()->RaycastSingle(query);
      if (results.Size())
      {
          RayQueryResult& result = results[0];
          hitPos = result.position_;
          hitDrawable = result.drawable_;
          return true;
      }
  
      return false;
  }
  
  void Decals::HandleUpdate(StringHash eventType, VariantMap& eventData)
  {
      using namespace Update;
  
      // Take the frame time step, which is stored as a float
      float timeStep = eventData[P_TIMESTEP].GetFloat();
  
      // Move the camera, scale movement with time step
      MoveCamera(timeStep);
  }
  
  void Decals::HandlePostRenderUpdate(StringHash eventType, VariantMap& eventData)
  {
      // If draw debug mode is enabled, draw viewport debug geometry. Disable depth test so that we can see the effect of occlusion
      if (drawDebug_)
          GetSubsystem<Renderer>()->DrawDebugGeometry(false);
  }
  