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/Urho3D.h>
  
  #include <Urho3D/Graphics/Camera.h>
  #include <Urho3D/Core/CoreEvents.h>
  #include <Urho3D/Engine/Engine.h>
  #include <Urho3D/UI/Font.h>
  #include <Urho3D/Graphics/Graphics.h>
  #include <Urho3D/Input/Input.h>
  #include <Urho3D/Graphics/Material.h>
  #include <Urho3D/Graphics/Model.h>
  #include <Urho3D/Graphics/Octree.h>
  #include <Urho3D/Graphics/Renderer.h>
  #include <Urho3D/Resource/ResourceCache.h>
  #include <Urho3D/Scene/Scene.h>
  #include <Urho3D/Graphics/StaticModel.h>
  #include <Urho3D/UI/Text.h>
  #include <Urho3D/UI/UI.h>
  
  #include "StaticScene.h"
  
  #include <Urho3D/DebugNew.h>
  
  DEFINE_APPLICATION_MAIN(StaticScene)
  
  StaticScene::StaticScene(Context* context) :
      Sample(context)
  {
  }
  
  void StaticScene::Start()
  {
      // Execute base class startup
      Sample::Start();
  
      // Create the scene content
      CreateScene();
  
      // Create the UI content
      CreateInstructions();
  
      // Setup the viewport for displaying the scene
      SetupViewport();
  
      // Hook up to the frame update events
      SubscribeToEvents();
  }
  
  void StaticScene::CreateScene()
  {
      ResourceCache* cache = GetSubsystem<ResourceCache>();
  
      scene_ = new Scene(context_);
  
      // 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)
      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 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)
      Node* lightNode = scene_->CreateChild("DirectionalLight");
      lightNode->SetDirection(Vector3(0.6f, -1.0f, 0.8f)); // The direction vector does not need to be normalized
      Light* light = lightNode->CreateComponent<Light>();
      light->SetLightType(LIGHT_DIRECTIONAL);
  
      // Create more StaticModel objects to the scene, randomly positioned, rotated and scaled. For rotation, we construct a
      // quaternion from Euler angles where the Y angle (rotation about the Y axis) is randomized. The mushroom model contains
      // LOD levels, so the StaticModel component will automatically select the LOD level according to the view distance (you'll
      // see the model get simpler as it moves further away). Finally, rendering a large number of the same object with the
      // same material allows instancing to be used, if the GPU supports it. This reduces the amount of CPU work in rendering the
      // scene.
      const unsigned NUM_OBJECTS = 200;
      for (unsigned i = 0; i < NUM_OBJECTS; ++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"));
      }
  
      // Create a scene node for the camera, which we will move around
      // The camera will use default settings (1000 far clip distance, 45 degrees FOV, set aspect ratio automatically)
      cameraNode_ = scene_->CreateChild("Camera");
      cameraNode_->CreateComponent<Camera>();
  
      // Set an initial position for the camera scene node above the plane
      cameraNode_->SetPosition(Vector3(0.0f, 5.0f, 0.0f));
  }
  
  void StaticScene::CreateInstructions()
  {
      ResourceCache* cache = GetSubsystem<ResourceCache>();
      UI* ui = GetSubsystem<UI>();
  
      // Construct new Text object, set string to display and font to use
      Text* instructionText = ui->GetRoot()->CreateChild<Text>();
      instructionText->SetText("Use WASD keys and mouse/touch to move");
      instructionText->SetFont(cache->GetResource<Font>("Fonts/Anonymous Pro.ttf"), 15);
  
      // Position the text relative to the screen center
      instructionText->SetHorizontalAlignment(HA_CENTER);
      instructionText->SetVerticalAlignment(VA_CENTER);
      instructionText->SetPosition(0, ui->GetRoot()->GetHeight() / 4);
  }
  
  void StaticScene::SetupViewport()
  {
      Renderer* renderer = GetSubsystem<Renderer>();
  
      // Set up a viewport to the Renderer subsystem so that the 3D scene can be seen. We need to define the scene and the camera
      // at minimum. Additionally we could configure the viewport screen size and the rendering path (eg. forward / deferred) to
      // use, but now we just use full screen and default render path configured in the engine command line options
      SharedPtr<Viewport> viewport(new Viewport(context_, scene_, cameraNode_->GetComponent<Camera>()));
      renderer->SetViewport(0, viewport);
  }
  
  void StaticScene::MoveCamera(float timeStep)
  {
      // Do not move if the UI has a focused element (the console)
      if (GetSubsystem<UI>()->GetFocusElement())
          return;
  
      Input* input = GetSubsystem<Input>();
  
      // 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
      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
      // Use the Translate() function (default local space) to move relative to the node's orientation.
      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);
  }
  
  void StaticScene::SubscribeToEvents()
  {
      // Subscribe HandleUpdate() function for processing update events
      SubscribeToEvent(E_UPDATE, HANDLER(StaticScene, HandleUpdate));
  }
  
  void StaticScene::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);
  }
  