/*
Bullet Continuous Collision Detection and Physics Library
Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/

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.
*/

#ifndef CONTACT_CONSTRAINT_H
#define CONTACT_CONSTRAINT_H

//todo: make into a proper class working with the iterative constraint solver

class btRigidBody;
#include "LinearMath/btVector3.h"
#include "LinearMath/btScalar.h"
struct btContactSolverInfo;
class btManifoldPoint;

enum {
	DEFAULT_CONTACT_SOLVER_TYPE=0,
	CONTACT_SOLVER_TYPE1,
	CONTACT_SOLVER_TYPE2,
	USER_CONTACT_SOLVER_TYPE1,
	MAX_CONTACT_SOLVER_TYPES
};


typedef float (*ContactSolverFunc)(btRigidBody& body1,
									 btRigidBody& body2,
									 class btManifoldPoint& contactPoint,
									 const btContactSolverInfo& info);

///stores some extra information to each contact point. It is not in the contact point, because that want to keep the collision detection independent from the constraint solver.
struct btConstraintPersistentData
{
	inline btConstraintPersistentData()
	:m_appliedImpulse(0.f),
	m_prevAppliedImpulse(0.f),
	m_accumulatedTangentImpulse0(0.f),
	m_accumulatedTangentImpulse1(0.f),
	m_jacDiagABInv(0.f),
	m_persistentLifeTime(0),
	m_restitution(0.f),
	m_friction(0.f),
	m_penetration(0.f),
	m_contactSolverFunc(0),
	m_frictionSolverFunc(0)
	{
	}
	
					
				/// total applied impulse during most recent frame
			float	m_appliedImpulse;
			float	m_prevAppliedImpulse;
			float	m_accumulatedTangentImpulse0;
			float	m_accumulatedTangentImpulse1;
			
			float	m_jacDiagABInv;
			float	m_jacDiagABInvTangent0;
			float	m_jacDiagABInvTangent1;
			int		m_persistentLifeTime;
			float	m_restitution;
			float	m_friction;
			float	m_penetration;
			btVector3	m_frictionWorldTangential0;
			btVector3	m_frictionWorldTangential1;
		
			ContactSolverFunc	m_contactSolverFunc;
			ContactSolverFunc	m_frictionSolverFunc;

};

///bilateral constraint between two dynamic objects
///positive distance = separation, negative distance = penetration
void resolveSingleBilateral(btRigidBody& body1, const btVector3& pos1,
                      btRigidBody& body2, const btVector3& pos2,
                      btScalar distance, const btVector3& normal,btScalar& impulse ,float timeStep);


///contact constraint resolution:
///calculate and apply impulse to satisfy non-penetration and non-negative relative velocity constraint
///positive distance = separation, negative distance = penetration
float resolveSingleCollision(
	btRigidBody& body1,
	btRigidBody& body2,
		btManifoldPoint& contactPoint,
		 const btContactSolverInfo& info);

float resolveSingleFriction(
	btRigidBody& body1,
	btRigidBody& body2,
	btManifoldPoint& contactPoint,
	const btContactSolverInfo& solverInfo
		);

#endif //CONTACT_CONSTRAINT_H
