/*
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.
*/
///btSoftBody implementation by Nathanael Presson

#ifndef _BT_SOFT_BODY_H
#define _BT_SOFT_BODY_H

#include "LinearMath/btAlignedObjectArray.h"
#include "LinearMath/btTransform.h"
#include "LinearMath/btIDebugDraw.h"
#include "BulletDynamics/Dynamics/btRigidBody.h"

#include "BulletCollision/CollisionShapes/btConcaveShape.h"
#include "BulletCollision/CollisionDispatch/btCollisionCreateFunc.h"
#include "btSparseSDF.h"
#include "BulletCollision/BroadphaseCollision/btDbvt.h"

//#ifdef BT_USE_DOUBLE_PRECISION
//#define btRigidBodyData	btRigidBodyDoubleData
//#define btRigidBodyDataName	"btRigidBodyDoubleData"
//#else
#define btSoftBodyData	btSoftBodyFloatData
#define btSoftBodyDataName	"btSoftBodyFloatData"
//#endif //BT_USE_DOUBLE_PRECISION

class btBroadphaseInterface;
class btDispatcher;
class btSoftBodySolver;

/* btSoftBodyWorldInfo	*/ 
struct	btSoftBodyWorldInfo
{
	btScalar				air_density;
	btScalar				water_density;
	btScalar				water_offset;
	btScalar				m_maxDisplacement;
	btVector3				water_normal;
	btBroadphaseInterface*	m_broadphase;
	btDispatcher*	m_dispatcher;
	btVector3				m_gravity;
	btSparseSdf<3>			m_sparsesdf;

	btSoftBodyWorldInfo()
		:air_density((btScalar)1.2),
		water_density(0),
		water_offset(0),
		m_maxDisplacement(1000.f),//avoid soft body from 'exploding' so use some upper threshold of maximum motion that a node can travel per frame
		water_normal(0,0,0),
		m_broadphase(0),
		m_dispatcher(0),
		m_gravity(0,-10,0)
	{
	}
};	


///The btSoftBody is an class to simulate cloth and volumetric soft bodies. 
///There is two-way interaction between btSoftBody and btRigidBody/btCollisionObject.
class	btSoftBody : public btCollisionObject
{
public:
	btAlignedObjectArray<const class btCollisionObject*> m_collisionDisabledObjects;

	// The solver object that handles this soft body
	btSoftBodySolver *m_softBodySolver;

	//
	// Enumerations
	//

	///eAeroModel 
	struct eAeroModel { enum _ {
		V_Point,			///Vertex normals are oriented toward velocity
		V_TwoSided,			///Vertex normals are flipped to match velocity	
		V_TwoSidedLiftDrag, ///Vertex normals are flipped to match velocity and lift and drag forces are applied
		V_OneSided,			///Vertex normals are taken as it is	
		F_TwoSided,			///Face normals are flipped to match velocity
		F_TwoSidedLiftDrag,	///Face normals are flipped to match velocity and lift and drag forces are applied 
		F_OneSided,			///Face normals are taken as it is		
		END
	};};

	///eVSolver : velocities solvers
	struct	eVSolver { enum _ {
		Linear,		///Linear solver
		END
	};};

	///ePSolver : positions solvers
	struct	ePSolver { enum _ {
		Linear,		///Linear solver
		Anchors,	///Anchor solver
		RContacts,	///Rigid contacts solver
		SContacts,	///Soft contacts solver
		END
	};};

	///eSolverPresets
	struct	eSolverPresets { enum _ {
		Positions,
		Velocities,
		Default	=	Positions,
		END
	};};

	///eFeature
	struct	eFeature { enum _ {
		None,
		Node,
		Link,
		Face,
		Tetra,
		END
	};};

	typedef btAlignedObjectArray<eVSolver::_>	tVSolverArray;
	typedef btAlignedObjectArray<ePSolver::_>	tPSolverArray;

	//
	// Flags
	//

	///fCollision
	struct fCollision { enum _ {
		RVSmask	=	0x000f,	///Rigid versus soft mask
		SDF_RS	=	0x0001,	///SDF based rigid vs soft
		CL_RS	=	0x0002, ///Cluster vs convex rigid vs soft

		SVSmask	=	0x0030,	///Rigid versus soft mask		
		VF_SS	=	0x0010,	///Vertex vs face soft vs soft handling
		CL_SS	=	0x0020, ///Cluster vs cluster soft vs soft handling
		CL_SELF =	0x0040, ///Cluster soft body self collision
		/* presets	*/ 
		Default	=	SDF_RS,
		END
	};};

	///fMaterial
	struct fMaterial { enum _ {
		DebugDraw	=	0x0001,	/// Enable debug draw
		/* presets	*/ 
		Default		=	DebugDraw,
		END
	};};

	//
	// API Types
	//

	/* sRayCast		*/ 
	struct sRayCast
	{
		btSoftBody*	body;		/// soft body
		eFeature::_	feature;	/// feature type
		int			index;		/// feature index
		btScalar	fraction;		/// time of impact fraction (rayorg+(rayto-rayfrom)*fraction)
	};

	/* ImplicitFn	*/ 
	struct	ImplicitFn
	{
		virtual btScalar	Eval(const btVector3& x)=0;
	};

	//
	// Internal types
	//

	typedef btAlignedObjectArray<btScalar>	tScalarArray;
	typedef btAlignedObjectArray<btVector3>	tVector3Array;

	/* sCti is Softbody contact info	*/ 
	struct	sCti
	{
		const btCollisionObject*	m_colObj;		/* Rigid body			*/ 
		btVector3		m_normal;	/* Outward normal		*/ 
		btScalar		m_offset;	/* Offset from origin	*/ 
	};	

	/* sMedium		*/ 
	struct	sMedium
	{
		btVector3		m_velocity;	/* Velocity				*/ 
		btScalar		m_pressure;	/* Pressure				*/ 
		btScalar		m_density;	/* Density				*/ 
	};

	/* Base type	*/ 
	struct	Element
	{
		void*			m_tag;			// User data
		Element() : m_tag(0) {}
	};
	/* Material		*/ 
	struct	Material : Element
	{
		btScalar				m_kLST;			// Linear stiffness coefficient [0,1]
		btScalar				m_kAST;			// Area/Angular stiffness coefficient [0,1]
		btScalar				m_kVST;			// Volume stiffness coefficient [0,1]
		int						m_flags;		// Flags
	};

	/* Feature		*/ 
	struct	Feature : Element
	{
		Material*				m_material;		// Material
	};
	/* Node			*/ 
	struct	Node : Feature
	{
		btVector3				m_x;			// Position
		btVector3				m_q;			// Previous step position
		btVector3				m_v;			// Velocity
		btVector3				m_f;			// Force accumulator
		btVector3				m_n;			// Normal
		btScalar				m_im;			// 1/mass
		btScalar				m_area;			// Area
		btDbvtNode*				m_leaf;			// Leaf data
		int						m_battach:1;	// Attached
	};
	/* Link			*/ 
	struct	Link : Feature
	{
		Node*					m_n[2];			// Node pointers
		btScalar				m_rl;			// Rest length		
		int						m_bbending:1;	// Bending link
		btScalar				m_c0;			// (ima+imb)*kLST
		btScalar				m_c1;			// rl^2
		btScalar				m_c2;			// |gradient|^2/c0
		btVector3				m_c3;			// gradient
	};
	/* Face			*/ 
	struct	Face : Feature
	{
		Node*					m_n[3];			// Node pointers
		btVector3				m_normal;		// Normal
		btScalar				m_ra;			// Rest area
		btDbvtNode*				m_leaf;			// Leaf data
	};
	/* Tetra		*/ 
	struct	Tetra : Feature
	{
		Node*					m_n[4];			// Node pointers		
		btScalar				m_rv;			// Rest volume
		btDbvtNode*				m_leaf;			// Leaf data
		btVector3				m_c0[4];		// gradients
		btScalar				m_c1;			// (4*kVST)/(im0+im1+im2+im3)
		btScalar				m_c2;			// m_c1/sum(|g0..3|^2)
	};
	/* RContact		*/ 
	struct	RContact
	{
		sCti		m_cti;			// Contact infos
		Node*					m_node;			// Owner node
		btMatrix3x3				m_c0;			// Impulse matrix
		btVector3				m_c1;			// Relative anchor
		btScalar				m_c2;			// ima*dt
		btScalar				m_c3;			// Friction
		btScalar				m_c4;			// Hardness
	};
	/* SContact		*/ 
	struct	SContact
	{
		Node*					m_node;			// Node
		Face*					m_face;			// Face
		btVector3				m_weights;		// Weigths
		btVector3				m_normal;		// Normal
		btScalar				m_margin;		// Margin
		btScalar				m_friction;		// Friction
		btScalar				m_cfm[2];		// Constraint force mixing
	};
	/* Anchor		*/ 
	struct	Anchor
	{
		Node*					m_node;			// Node pointer
		btVector3				m_local;		// Anchor position in body space
		btRigidBody*			m_body;			// Body
		btScalar				m_influence;
		btMatrix3x3				m_c0;			// Impulse matrix
		btVector3				m_c1;			// Relative anchor
		btScalar				m_c2;			// ima*dt
	};
	/* Note			*/ 
	struct	Note : Element
	{
		const char*				m_text;			// Text
		btVector3				m_offset;		// Offset
		int						m_rank;			// Rank
		Node*					m_nodes[4];		// Nodes
		btScalar				m_coords[4];	// Coordinates
	};	
	/* Pose			*/ 
	struct	Pose
	{
		bool					m_bvolume;		// Is valid
		bool					m_bframe;		// Is frame
		btScalar				m_volume;		// Rest volume
		tVector3Array			m_pos;			// Reference positions
		tScalarArray			m_wgh;			// Weights
		btVector3				m_com;			// COM
		btMatrix3x3				m_rot;			// Rotation
		btMatrix3x3				m_scl;			// Scale
		btMatrix3x3				m_aqq;			// Base scaling
	};
	/* Cluster		*/ 
	struct	Cluster
	{
		tScalarArray				m_masses;
		btAlignedObjectArray<Node*>	m_nodes;		
		tVector3Array				m_framerefs;
		btTransform					m_framexform;
		btScalar					m_idmass;
		btScalar					m_imass;
		btMatrix3x3					m_locii;
		btMatrix3x3					m_invwi;
		btVector3					m_com;
		btVector3					m_vimpulses[2];
		btVector3					m_dimpulses[2];
		int							m_nvimpulses;
		int							m_ndimpulses;
		btVector3					m_lv;
		btVector3					m_av;
		btDbvtNode*					m_leaf;
		btScalar					m_ndamping;	/* Node damping		*/ 
		btScalar					m_ldamping;	/* Linear damping	*/ 
		btScalar					m_adamping;	/* Angular damping	*/ 
		btScalar					m_matching;
		btScalar					m_maxSelfCollisionImpulse;
		btScalar					m_selfCollisionImpulseFactor;
		bool						m_containsAnchor;
		bool						m_collide;
		int							m_clusterIndex;
		Cluster() : m_leaf(0),m_ndamping(0),m_ldamping(0),m_adamping(0),m_matching(0) 
		,m_maxSelfCollisionImpulse(100.f),
		m_selfCollisionImpulseFactor(0.01f),
		m_containsAnchor(false)
		{}
	};
	/* Impulse		*/ 
	struct	Impulse
	{
		btVector3					m_velocity;
		btVector3					m_drift;
		int							m_asVelocity:1;
		int							m_asDrift:1;
		Impulse() : m_velocity(0,0,0),m_drift(0,0,0),m_asVelocity(0),m_asDrift(0)	{}
		Impulse						operator -() const
		{
			Impulse i=*this;
			i.m_velocity=-i.m_velocity;
			i.m_drift=-i.m_drift;
			return(i);
		}
		Impulse						operator*(btScalar x) const
		{
			Impulse i=*this;
			i.m_velocity*=x;
			i.m_drift*=x;
			return(i);
		}
	};
	/* Body			*/ 
	struct	Body
	{
		Cluster*			m_soft;
		btRigidBody*		m_rigid;
		const btCollisionObject*	m_collisionObject;

		Body() : m_soft(0),m_rigid(0),m_collisionObject(0)				{}
		Body(Cluster* p) : m_soft(p),m_rigid(0),m_collisionObject(0)	{}
		Body(const btCollisionObject* colObj) : m_soft(0),m_collisionObject(colObj)
		{
			m_rigid = (btRigidBody*)btRigidBody::upcast(m_collisionObject);
		}

		void						activate() const
		{
			if(m_rigid) 
				m_rigid->activate();
			if (m_collisionObject)
				m_collisionObject->activate();

		}
		const btMatrix3x3&			invWorldInertia() const
		{
			static const btMatrix3x3	iwi(0,0,0,0,0,0,0,0,0);
			if(m_rigid) return(m_rigid->getInvInertiaTensorWorld());
			if(m_soft)	return(m_soft->m_invwi);
			return(iwi);
		}
		btScalar					invMass() const
		{
			if(m_rigid) return(m_rigid->getInvMass());
			if(m_soft)	return(m_soft->m_imass);
			return(0);
		}
		const btTransform&			xform() const
		{
			static const btTransform	identity=btTransform::getIdentity();		
			if(m_collisionObject) return(m_collisionObject->getWorldTransform());
			if(m_soft)	return(m_soft->m_framexform);
			return(identity);
		}
		btVector3					linearVelocity() const
		{
			if(m_rigid) return(m_rigid->getLinearVelocity());
			if(m_soft)	return(m_soft->m_lv);
			return(btVector3(0,0,0));
		}
		btVector3					angularVelocity(const btVector3& rpos) const
		{			
			if(m_rigid) return(btCross(m_rigid->getAngularVelocity(),rpos));
			if(m_soft)	return(btCross(m_soft->m_av,rpos));
			return(btVector3(0,0,0));
		}
		btVector3					angularVelocity() const
		{			
			if(m_rigid) return(m_rigid->getAngularVelocity());
			if(m_soft)	return(m_soft->m_av);
			return(btVector3(0,0,0));
		}
		btVector3					velocity(const btVector3& rpos) const
		{
			return(linearVelocity()+angularVelocity(rpos));
		}
		void						applyVImpulse(const btVector3& impulse,const btVector3& rpos) const
		{
			if(m_rigid)	m_rigid->applyImpulse(impulse,rpos);
			if(m_soft)	btSoftBody::clusterVImpulse(m_soft,rpos,impulse);
		}
		void						applyDImpulse(const btVector3& impulse,const btVector3& rpos) const
		{
			if(m_rigid)	m_rigid->applyImpulse(impulse,rpos);
			if(m_soft)	btSoftBody::clusterDImpulse(m_soft,rpos,impulse);
		}		
		void						applyImpulse(const Impulse& impulse,const btVector3& rpos) const
		{
			if(impulse.m_asVelocity)	
			{
//				printf("impulse.m_velocity = %f,%f,%f\n",impulse.m_velocity.getX(),impulse.m_velocity.getY(),impulse.m_velocity.getZ());
				applyVImpulse(impulse.m_velocity,rpos);
			}
			if(impulse.m_asDrift)		
			{
//				printf("impulse.m_drift = %f,%f,%f\n",impulse.m_drift.getX(),impulse.m_drift.getY(),impulse.m_drift.getZ());
				applyDImpulse(impulse.m_drift,rpos);
			}
		}
		void						applyVAImpulse(const btVector3& impulse) const
		{
			if(m_rigid)	m_rigid->applyTorqueImpulse(impulse);
			if(m_soft)	btSoftBody::clusterVAImpulse(m_soft,impulse);
		}
		void						applyDAImpulse(const btVector3& impulse) const
		{
			if(m_rigid)	m_rigid->applyTorqueImpulse(impulse);
			if(m_soft)	btSoftBody::clusterDAImpulse(m_soft,impulse);
		}
		void						applyAImpulse(const Impulse& impulse) const
		{
			if(impulse.m_asVelocity)	applyVAImpulse(impulse.m_velocity);
			if(impulse.m_asDrift)		applyDAImpulse(impulse.m_drift);
		}
		void						applyDCImpulse(const btVector3& impulse) const
		{
			if(m_rigid)	m_rigid->applyCentralImpulse(impulse);
			if(m_soft)	btSoftBody::clusterDCImpulse(m_soft,impulse);
		}
	};
	/* Joint		*/ 
	struct	Joint
	{
		struct eType { enum _ {
			Linear=0,
			Angular,
			Contact
		};};
		struct Specs
		{
			Specs() : erp(1),cfm(1),split(1) {}
			btScalar	erp;
			btScalar	cfm;
			btScalar	split;
		};
		Body						m_bodies[2];
		btVector3					m_refs[2];
		btScalar					m_cfm;
		btScalar					m_erp;
		btScalar					m_split;
		btVector3					m_drift;
		btVector3					m_sdrift;
		btMatrix3x3					m_massmatrix;
		bool						m_delete;
		virtual						~Joint() {}
		Joint() : m_delete(false) {}
		virtual void				Prepare(btScalar dt,int iterations);
		virtual void				Solve(btScalar dt,btScalar sor)=0;
		virtual void				Terminate(btScalar dt)=0;
		virtual eType::_			Type() const=0;
	};
	/* LJoint		*/ 
	struct	LJoint : Joint
	{
		struct Specs : Joint::Specs
		{
			btVector3	position;
		};		
		btVector3					m_rpos[2];
		void						Prepare(btScalar dt,int iterations);
		void						Solve(btScalar dt,btScalar sor);
		void						Terminate(btScalar dt);
		eType::_					Type() const { return(eType::Linear); }
	};
	/* AJoint		*/ 
	struct	AJoint : Joint
	{
		struct IControl
		{
			virtual void			Prepare(AJoint*)				{}
			virtual btScalar		Speed(AJoint*,btScalar current) { return(current); }
			static IControl*		Default()						{ static IControl def;return(&def); }
		};
		struct Specs : Joint::Specs
		{
			Specs() : icontrol(IControl::Default()) {}
			btVector3	axis;
			IControl*	icontrol;
		};		
		btVector3					m_axis[2];
		IControl*					m_icontrol;
		void						Prepare(btScalar dt,int iterations);
		void						Solve(btScalar dt,btScalar sor);
		void						Terminate(btScalar dt);
		eType::_					Type() const { return(eType::Angular); }
	};
	/* CJoint		*/ 
	struct	CJoint : Joint
	{		
		int							m_life;
		int							m_maxlife;
		btVector3					m_rpos[2];
		btVector3					m_normal;
		btScalar					m_friction;
		void						Prepare(btScalar dt,int iterations);
		void						Solve(btScalar dt,btScalar sor);
		void						Terminate(btScalar dt);
		eType::_					Type() const { return(eType::Contact); }
	};
	/* Config		*/ 
	struct	Config
	{
		eAeroModel::_			aeromodel;		// Aerodynamic model (default: V_Point)
		btScalar				kVCF;			// Velocities correction factor (Baumgarte)
		btScalar				kDP;			// Damping coefficient [0,1]
		btScalar				kDG;			// Drag coefficient [0,+inf]
		btScalar				kLF;			// Lift coefficient [0,+inf]
		btScalar				kPR;			// Pressure coefficient [-inf,+inf]
		btScalar				kVC;			// Volume conversation coefficient [0,+inf]
		btScalar				kDF;			// Dynamic friction coefficient [0,1]
		btScalar				kMT;			// Pose matching coefficient [0,1]		
		btScalar				kCHR;			// Rigid contacts hardness [0,1]
		btScalar				kKHR;			// Kinetic contacts hardness [0,1]
		btScalar				kSHR;			// Soft contacts hardness [0,1]
		btScalar				kAHR;			// Anchors hardness [0,1]
		btScalar				kSRHR_CL;		// Soft vs rigid hardness [0,1] (cluster only)
		btScalar				kSKHR_CL;		// Soft vs kinetic hardness [0,1] (cluster only)
		btScalar				kSSHR_CL;		// Soft vs soft hardness [0,1] (cluster only)
		btScalar				kSR_SPLT_CL;	// Soft vs rigid impulse split [0,1] (cluster only)
		btScalar				kSK_SPLT_CL;	// Soft vs rigid impulse split [0,1] (cluster only)
		btScalar				kSS_SPLT_CL;	// Soft vs rigid impulse split [0,1] (cluster only)
		btScalar				maxvolume;		// Maximum volume ratio for pose
		btScalar				timescale;		// Time scale
		int						viterations;	// Velocities solver iterations
		int						piterations;	// Positions solver iterations
		int						diterations;	// Drift solver iterations
		int						citerations;	// Cluster solver iterations
		int						collisions;		// Collisions flags
		tVSolverArray			m_vsequence;	// Velocity solvers sequence
		tPSolverArray			m_psequence;	// Position solvers sequence
		tPSolverArray			m_dsequence;	// Drift solvers sequence
	};
	/* SolverState	*/ 
	struct	SolverState
	{
		btScalar				sdt;			// dt*timescale
		btScalar				isdt;			// 1/sdt
		btScalar				velmrg;			// velocity margin
		btScalar				radmrg;			// radial margin
		btScalar				updmrg;			// Update margin
	};	
	/// RayFromToCaster takes a ray from, ray to (instead of direction!)
	struct	RayFromToCaster : btDbvt::ICollide
	{
		btVector3			m_rayFrom;
		btVector3			m_rayTo;
		btVector3			m_rayNormalizedDirection;
		btScalar			m_mint;
		Face*				m_face;
		int					m_tests;
		RayFromToCaster(const btVector3& rayFrom,const btVector3& rayTo,btScalar mxt);
		void					Process(const btDbvtNode* leaf);

		static inline btScalar	rayFromToTriangle(const btVector3& rayFrom,
			const btVector3& rayTo,
			const btVector3& rayNormalizedDirection,
			const btVector3& a,
			const btVector3& b,
			const btVector3& c,
			btScalar maxt=SIMD_INFINITY);
	};

	//
	// Typedefs
	//

	typedef void								(*psolver_t)(btSoftBody*,btScalar,btScalar);
	typedef void								(*vsolver_t)(btSoftBody*,btScalar);
	typedef btAlignedObjectArray<Cluster*>		tClusterArray;
	typedef btAlignedObjectArray<Note>			tNoteArray;
	typedef btAlignedObjectArray<Node>			tNodeArray;
	typedef btAlignedObjectArray<btDbvtNode*>	tLeafArray;
	typedef btAlignedObjectArray<Link>			tLinkArray;
	typedef btAlignedObjectArray<Face>			tFaceArray;
	typedef btAlignedObjectArray<Tetra>			tTetraArray;
	typedef btAlignedObjectArray<Anchor>		tAnchorArray;
	typedef btAlignedObjectArray<RContact>		tRContactArray;
	typedef btAlignedObjectArray<SContact>		tSContactArray;
	typedef btAlignedObjectArray<Material*>		tMaterialArray;
	typedef btAlignedObjectArray<Joint*>		tJointArray;
	typedef btAlignedObjectArray<btSoftBody*>	tSoftBodyArray;	

	//
	// Fields
	//

	Config					m_cfg;			// Configuration
	SolverState				m_sst;			// Solver state
	Pose					m_pose;			// Pose
	void*					m_tag;			// User data
	btSoftBodyWorldInfo*	m_worldInfo;	// World info
	tNoteArray				m_notes;		// Notes
	tNodeArray				m_nodes;		// Nodes
	tLinkArray				m_links;		// Links
	tFaceArray				m_faces;		// Faces
	tTetraArray				m_tetras;		// Tetras
	tAnchorArray			m_anchors;		// Anchors
	tRContactArray			m_rcontacts;	// Rigid contacts
	tSContactArray			m_scontacts;	// Soft contacts
	tJointArray				m_joints;		// Joints
	tMaterialArray			m_materials;	// Materials
	btScalar				m_timeacc;		// Time accumulator
	btVector3				m_bounds[2];	// Spatial bounds	
	bool					m_bUpdateRtCst;	// Update runtime constants
	btDbvt					m_ndbvt;		// Nodes tree
	btDbvt					m_fdbvt;		// Faces tree
	btDbvt					m_cdbvt;		// Clusters tree
	tClusterArray			m_clusters;		// Clusters

	btAlignedObjectArray<bool>m_clusterConnectivity;//cluster connectivity, for self-collision

	btTransform			m_initialWorldTransform;

	btVector3			m_windVelocity;
	
	btScalar        m_restLengthScale;
	
	//
	// Api
	//

	/* ctor																	*/ 
	btSoftBody(	btSoftBodyWorldInfo* worldInfo,int node_count,		const btVector3* x,		const btScalar* m);

	/* ctor																	*/ 
	btSoftBody(	btSoftBodyWorldInfo* worldInfo);

	void	initDefaults();

	/* dtor																	*/ 
	virtual ~btSoftBody();
	/* Check for existing link												*/ 

	btAlignedObjectArray<int>	m_userIndexMapping;

	btSoftBodyWorldInfo*	getWorldInfo()
	{
		return m_worldInfo;
	}

	///@todo: avoid internal softbody shape hack and move collision code to collision library
	virtual void	setCollisionShape(btCollisionShape* collisionShape)
	{
		
	}

	bool				checkLink(	int node0,
		int node1) const;
	bool				checkLink(	const Node* node0,
		const Node* node1) const;
	/* Check for existring face												*/ 
	bool				checkFace(	int node0,
		int node1,
		int node2) const;
	/* Append material														*/ 
	Material*			appendMaterial();
	/* Append note															*/ 
	void				appendNote(	const char* text,
		const btVector3& o,
		const btVector4& c=btVector4(1,0,0,0),
		Node* n0=0,
		Node* n1=0,
		Node* n2=0,
		Node* n3=0);
	void				appendNote(	const char* text,
		const btVector3& o,
		Node* feature);
	void				appendNote(	const char* text,
		const btVector3& o,
		Link* feature);
	void				appendNote(	const char* text,
		const btVector3& o,
		Face* feature);
	/* Append node															*/ 
	void				appendNode(	const btVector3& x,btScalar m);
	/* Append link															*/ 
	void				appendLink(int model=-1,Material* mat=0);
	void				appendLink(	int node0,
		int node1,
		Material* mat=0,
		bool bcheckexist=false);
	void				appendLink(	Node* node0,
		Node* node1,
		Material* mat=0,
		bool bcheckexist=false);
	/* Append face															*/ 
	void				appendFace(int model=-1,Material* mat=0);
	void				appendFace(	int node0,
		int node1,
		int node2,
		Material* mat=0);
	void			appendTetra(int model,Material* mat);
	//
	void			appendTetra(int node0,
										int node1,
										int node2,
										int node3,
										Material* mat=0);


	/* Append anchor														*/ 
	void				appendAnchor(	int node,
		btRigidBody* body, bool disableCollisionBetweenLinkedBodies=false,btScalar influence = 1);
	void			appendAnchor(int node,btRigidBody* body, const btVector3& localPivot,bool disableCollisionBetweenLinkedBodies=false,btScalar influence = 1);
	/* Append linear joint													*/ 
	void				appendLinearJoint(const LJoint::Specs& specs,Cluster* body0,Body body1);
	void				appendLinearJoint(const LJoint::Specs& specs,Body body=Body());
	void				appendLinearJoint(const LJoint::Specs& specs,btSoftBody* body);
	/* Append linear joint													*/ 
	void				appendAngularJoint(const AJoint::Specs& specs,Cluster* body0,Body body1);
	void				appendAngularJoint(const AJoint::Specs& specs,Body body=Body());
	void				appendAngularJoint(const AJoint::Specs& specs,btSoftBody* body);
	/* Add force (or gravity) to the entire body							*/ 
	void				addForce(		const btVector3& force);
	/* Add force (or gravity) to a node of the body							*/ 
	void				addForce(		const btVector3& force,
		int node);
	/* Add aero force to a node of the body */
	void			    addAeroForceToNode(const btVector3& windVelocity,int nodeIndex);

	/* Add aero force to a face of the body */
	void			    addAeroForceToFace(const btVector3& windVelocity,int faceIndex);

	/* Add velocity to the entire body										*/ 
	void				addVelocity(	const btVector3& velocity);

	/* Set velocity for the entire body										*/ 
	void				setVelocity(	const btVector3& velocity);

	/* Add velocity to a node of the body									*/ 
	void				addVelocity(	const btVector3& velocity,
		int node);
	/* Set mass																*/ 
	void				setMass(		int node,
		btScalar mass);
	/* Get mass																*/ 
	btScalar			getMass(		int node) const;
	/* Get total mass														*/ 
	btScalar			getTotalMass() const;
	/* Set total mass (weighted by previous masses)							*/ 
	void				setTotalMass(	btScalar mass,
		bool fromfaces=false);
	/* Set total density													*/ 
	void				setTotalDensity(btScalar density);
	/* Set volume mass (using tetrahedrons)									*/
	void				setVolumeMass(		btScalar mass);
	/* Set volume density (using tetrahedrons)								*/
	void				setVolumeDensity(	btScalar density);
	/* Transform															*/ 
	void				transform(		const btTransform& trs);
	/* Translate															*/ 
	void				translate(		const btVector3& trs);
	/* Rotate															*/ 
	void				rotate(	const btQuaternion& rot);
	/* Scale																*/ 
	void				scale(	const btVector3& scl);
	/* Get link resting lengths scale										*/
	btScalar			getRestLengthScale();
	/* Scale resting length of all springs									*/
	void				setRestLengthScale(btScalar restLength);
	/* Set current state as pose											*/ 
	void				setPose(		bool bvolume,
		bool bframe);
	/* Set current link lengths as resting lengths							*/ 
	void				resetLinkRestLengths();
	/* Return the volume													*/ 
	btScalar			getVolume() const;
	/* Cluster count														*/ 
	int					clusterCount() const;
	/* Cluster center of mass												*/ 
	static btVector3	clusterCom(const Cluster* cluster);
	btVector3			clusterCom(int cluster) const;
	/* Cluster velocity at rpos												*/ 
	static btVector3	clusterVelocity(const Cluster* cluster,const btVector3& rpos);
	/* Cluster impulse														*/ 
	static void			clusterVImpulse(Cluster* cluster,const btVector3& rpos,const btVector3& impulse);
	static void			clusterDImpulse(Cluster* cluster,const btVector3& rpos,const btVector3& impulse);
	static void			clusterImpulse(Cluster* cluster,const btVector3& rpos,const Impulse& impulse);
	static void			clusterVAImpulse(Cluster* cluster,const btVector3& impulse);
	static void			clusterDAImpulse(Cluster* cluster,const btVector3& impulse);
	static void			clusterAImpulse(Cluster* cluster,const Impulse& impulse);
	static void			clusterDCImpulse(Cluster* cluster,const btVector3& impulse);
	/* Generate bending constraints based on distance in the adjency graph	*/ 
	int					generateBendingConstraints(	int distance,
		Material* mat=0);
	/* Randomize constraints to reduce solver bias							*/ 
	void				randomizeConstraints();
	/* Release clusters														*/ 
	void				releaseCluster(int index);
	void				releaseClusters();
	/* Generate clusters (K-mean)											*/ 
	///generateClusters with k=0 will create a convex cluster for each tetrahedron or triangle
	///otherwise an approximation will be used (better performance)
	int					generateClusters(int k,int maxiterations=8192);
	/* Refine																*/ 
	void				refine(ImplicitFn* ifn,btScalar accurary,bool cut);
	/* CutLink																*/ 
	bool				cutLink(int node0,int node1,btScalar position);
	bool				cutLink(const Node* node0,const Node* node1,btScalar position);

	///Ray casting using rayFrom and rayTo in worldspace, (not direction!)
	bool				rayTest(const btVector3& rayFrom,
		const btVector3& rayTo,
		sRayCast& results);
	/* Solver presets														*/ 
	void				setSolver(eSolverPresets::_ preset);
	/* predictMotion														*/ 
	void				predictMotion(btScalar dt);
	/* solveConstraints														*/ 
	void				solveConstraints();
	/* staticSolve															*/ 
	void				staticSolve(int iterations);
	/* solveCommonConstraints												*/ 
	static void			solveCommonConstraints(btSoftBody** bodies,int count,int iterations);
	/* solveClusters														*/ 
	static void			solveClusters(const btAlignedObjectArray<btSoftBody*>& bodies);
	/* integrateMotion														*/ 
	void				integrateMotion();
	/* defaultCollisionHandlers												*/ 
	void				defaultCollisionHandler(const btCollisionObjectWrapper* pcoWrap);
	void				defaultCollisionHandler(btSoftBody* psb);



	//
	// Functionality to deal with new accelerated solvers.
	//

	/**
	 * Set a wind velocity for interaction with the air.
	 */
	void setWindVelocity( const btVector3 &velocity );


	/**
	 * Return the wind velocity for interaction with the air.
	 */
	const btVector3& getWindVelocity();

	//
	// Set the solver that handles this soft body
	// Should not be allowed to get out of sync with reality
	// Currently called internally on addition to the world
	void setSoftBodySolver( btSoftBodySolver *softBodySolver )
	{
		m_softBodySolver = softBodySolver;
	}

	//
	// Return the solver that handles this soft body
	// 
	btSoftBodySolver *getSoftBodySolver()
	{
		return m_softBodySolver;
	}

	//
	// Return the solver that handles this soft body
	// 
	btSoftBodySolver *getSoftBodySolver() const
	{
		return m_softBodySolver;
	}


	//
	// Cast
	//

	static const btSoftBody*	upcast(const btCollisionObject* colObj)
	{
		if (colObj->getInternalType()==CO_SOFT_BODY)
			return (const btSoftBody*)colObj;
		return 0;
	}
	static btSoftBody*			upcast(btCollisionObject* colObj)
	{
		if (colObj->getInternalType()==CO_SOFT_BODY)
			return (btSoftBody*)colObj;
		return 0;
	}

	//
	// ::btCollisionObject
	//

	virtual void getAabb(btVector3& aabbMin,btVector3& aabbMax) const
	{
		aabbMin = m_bounds[0];
		aabbMax = m_bounds[1];
	}
	//
	// Private
	//
	void				pointersToIndices();
	void				indicesToPointers(const int* map=0);

	int					rayTest(const btVector3& rayFrom,const btVector3& rayTo,
		btScalar& mint,eFeature::_& feature,int& index,bool bcountonly) const;
	void				initializeFaceTree();
	btVector3			evaluateCom() const;
	bool				checkContact(const btCollisionObjectWrapper* colObjWrap,const btVector3& x,btScalar margin,btSoftBody::sCti& cti) const;
	void				updateNormals();
	void				updateBounds();
	void				updatePose();
	void				updateConstants();
	void				updateLinkConstants();
	void				updateArea(bool averageArea = true);
	void				initializeClusters();
	void				updateClusters();
	void				cleanupClusters();
	void				prepareClusters(int iterations);
	void				solveClusters(btScalar sor);
	void				applyClusters(bool drift);
	void				dampClusters();
	void				applyForces();	
	static void			PSolve_Anchors(btSoftBody* psb,btScalar kst,btScalar ti);
	static void			PSolve_RContacts(btSoftBody* psb,btScalar kst,btScalar ti);
	static void			PSolve_SContacts(btSoftBody* psb,btScalar,btScalar ti);
	static void			PSolve_Links(btSoftBody* psb,btScalar kst,btScalar ti);
	static void			VSolve_Links(btSoftBody* psb,btScalar kst);
	static psolver_t	getSolver(ePSolver::_ solver);
	static vsolver_t	getSolver(eVSolver::_ solver);


	virtual	int	calculateSerializeBufferSize()	const;

	///fills the dataBuffer and returns the struct name (and 0 on failure)
	virtual	const char*	serialize(void* dataBuffer,  class btSerializer* serializer) const;

	//virtual void serializeSingleObject(class btSerializer* serializer) const;


};




#endif //_BT_SOFT_BODY_H
