text: /**
   * Copyright (c) 2006-2016 LOVE Development Team
   *
   * This software is provided 'as-is', without any express or implied
   * warranty.  In no event will the authors be held liable for any damages
   * arising from the use of this software.
   *
   * Permission is granted to anyone to use this software for any purpose,
   * including commercial applications, and to alter it and redistribute it
   * freely, subject to the following restrictions:
   *
   * 1. The origin of this software must not be misrepresented; you must not
   *    claim that you wrote the original software. If you use this software
   *    in a product, an acknowledgment in the product documentation would be
   *    appreciated but is not required.
   * 2. Altered source versions must be plainly marked as such, and must not be
   *    misrepresented as being the original software.
   * 3. This notice may not be removed or altered from any source distribution.
   **/
  
  #include "Contact.h"
  #include "World.h"
  #include "Physics.h"
  
  #include "common/Memoizer.h"
  
  namespace love
  {
  namespace physics
  {
  namespace box2d
  {
  
  Contact::Contact(b2Contact *contact)
  	: contact(contact)
  {
  	Memoizer::add(contact, this);
  }
  
  Contact::~Contact()
  {
  	invalidate();
  }
  
  void Contact::invalidate()
  {
  	if (contact != NULL)
  	{
  		Memoizer::remove(contact);
  		contact = NULL;
  	}
  }
  
  bool Contact::isValid()
  {
  	return contact != NULL ? true : false;
  }
  
  int Contact::getPositions(lua_State *L)
  {
  	love::luax_assert_argc(L, 1, 1);
  	b2WorldManifold manifold;
  	contact->GetWorldManifold(&manifold);
  	int points = contact->GetManifold()->pointCount;
  	for (int i = 0; i < points; i++)
  	{
  		b2Vec2 position = Physics::scaleUp(manifold.points[i]);
  		lua_pushnumber(L, position.x);
  		lua_pushnumber(L, position.y);
  	}
  	return points*2;
  }
  
  int Contact::getNormal(lua_State *L)
  {
  	love::luax_assert_argc(L, 1, 1);
  	b2WorldManifold manifold;
  	contact->GetWorldManifold(&manifold);
  	lua_pushnumber(L, manifold.normal.x);
  	lua_pushnumber(L, manifold.normal.y);
  	return 2;
  }
  
  float Contact::getFriction() const
  {
  	return contact->GetFriction();
  }
  
  float Contact::getRestitution() const
  {
  	return contact->GetRestitution();
  }
  
  bool Contact::isEnabled() const
  {
  	return contact->IsEnabled();
  }
  
  bool Contact::isTouching() const
  {
  	return contact->IsTouching();
  }
  
  void Contact::setFriction(float friction)
  {
  	contact->SetFriction(friction);
  }
  
  void Contact::setRestitution(float restitution)
  {
  	contact->SetRestitution(restitution);
  }
  
  void Contact::setEnabled(bool enabled)
  {
  	contact->SetEnabled(enabled);
  }
  
  void Contact::resetFriction()
  {
  	contact->ResetFriction();
  }
  
  void Contact::resetRestitution()
  {
  	contact->ResetRestitution();
  }
  
  void Contact::setTangentSpeed(float speed)
  {
  	contact->SetTangentSpeed(speed);
  }
  
  float Contact::getTangentSpeed() const
  {
  	return contact->GetTangentSpeed();
  }
  
  void Contact::getChildren(int &childA, int &childB)
  {
  	childA = contact->GetChildIndexA();
  	childB = contact->GetChildIndexB();
  }
  
  void Contact::getFixtures(Fixture *&fixtureA, Fixture *&fixtureB)
  {
  	fixtureA = (Fixture *) Memoizer::find(contact->GetFixtureA());
  	fixtureB = (Fixture *) Memoizer::find(contact->GetFixtureB());
  
  	if (!fixtureA || !fixtureB)
  		throw love::Exception("A fixture has escaped Memoizer!");
  }
  
  } // box2d
  } // physics
  } // love
  