text: /*
   * This source file is part of libRocket, the HTML/CSS Interface Middleware
   *
   * For the latest information, see http://www.librocket.com
   *
   * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
   *
   * 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 "DecoratorStarfield.h"
  #include <Rocket/Core/Math.h>
  #include <Rocket/Core/Element.h>
  #include <Shell.h>
  #include <ShellOpenGL.h>
  #include "GameDetails.h"
  
  float last_update_time = 0.0f;
  
  DecoratorStarfield::~DecoratorStarfield()
  {
  }
  
  bool DecoratorStarfield::Initialise(int _num_layers, const Rocket::Core::Colourb& _top_colour, const Rocket::Core::Colourb& _bottom_colour, float _top_speed, float _bottom_speed, int _top_density, int _bottom_density)
  {
  	num_layers = _num_layers;
  	top_colour = _top_colour;
  	bottom_colour = _bottom_colour;
  	top_speed = _top_speed;
  	bottom_speed = _bottom_speed;
  	top_density = _top_density;
  	bottom_density = _bottom_density;
  
  	return true;
  }
  
  /// Called on a decorator to generate any required per-element data for a newly decorated element.
  Rocket::Core::DecoratorDataHandle DecoratorStarfield::GenerateElementData(Rocket::Core::Element* element)
  {
  	StarField* star_field = new StarField();
  
  	star_field->star_layers.resize(num_layers);
  
  	for (int i = 0; i < num_layers; i++)
  	{
  		float layer_depth = i / (float)num_layers;
  
  		int density = Rocket::Core::Math::RealToInteger((top_density * layer_depth) + (bottom_density * (1.0f - layer_depth)));
  		star_field->star_layers[i].stars.resize(density);
  
  		Rocket::Core::Colourb colour = (top_colour * layer_depth) + (bottom_colour * (1.0f - layer_depth));
  		star_field->star_layers[i].colour = colour;
  
  		float speed = (top_speed * layer_depth) + (bottom_speed * (1.0f - layer_depth));
  		star_field->star_layers[i].speed = speed;
  
  		star_field->dimensions = element->GetBox().GetSize(Rocket::Core::Box::PADDING);
  
  		if (star_field->dimensions.x > 0)
  		{
  			for (int j = 0; j < density; j++)
  			{
  				star_field->star_layers[i].stars[j].x = (float) Rocket::Core::Math::RandomReal(star_field->dimensions.x);
  				star_field->star_layers[i].stars[j].y = (float) Rocket::Core::Math::RandomReal(star_field->dimensions.y);
  			}
  		}
  
  		star_field->last_update = Shell::GetElapsedTime();
  	}
  
  	return reinterpret_cast<Rocket::Core::DecoratorDataHandle>(star_field);
  }
  
  // Called to release element data generated by this decorator.
  void DecoratorStarfield::ReleaseElementData(Rocket::Core::DecoratorDataHandle element_data)
  {
  	delete reinterpret_cast<StarField*>(element_data);
  }
  
  // Called to render the decorator on an element.
  void DecoratorStarfield::RenderElement(Rocket::Core::Element* ROCKET_UNUSED_PARAMETER(element), Rocket::Core::DecoratorDataHandle element_data)
  {
  	ROCKET_UNUSED(element);
  
  	StarField* star_field = reinterpret_cast<StarField*>(element_data);
  	star_field->Update();
  
  	glDisable(GL_TEXTURE_2D);
  	glPointSize(2);
  	glBegin(GL_POINTS);
  
  	for (size_t i = 0; i < star_field->star_layers.size(); i++)
  	{
  		glColor4ubv(star_field->star_layers[i].colour);
  		
  		for (size_t j = 0; j < star_field->star_layers[i].stars.size(); j++)
  		{
  			glVertex2f(star_field->star_layers[i].stars[j].x, star_field->star_layers[i].stars[j].y);
  		}
  	}
  
  	glEnd();
  
  	glColor4ub(255, 255, 255, 255);
  }
  
  void DecoratorStarfield::StarField::Update()
  {
  	float time = Shell::GetElapsedTime();
  	float delta_time = time - last_update;
  	last_update = time;
  
  	if (!GameDetails::GetPaused())
  	{
  		for (size_t i = 0; i < star_layers.size(); i++)
  		{
  			float movement = star_layers[i].speed * delta_time;
  
  			for (size_t j = 0; j < star_layers[i].stars.size(); j++)
  			{
  				star_layers[i].stars[j].y += movement;
  				if (star_layers[i].stars[j].y > dimensions.y)
  				{
  					star_layers[i].stars[j].y = 0;
  					star_layers[i].stars[j].x = Rocket::Core::Math::RandomReal(dimensions.x);
  				}
  			}
  		}
  	}
  }
  