class CJoint2{
public:
	CVertex2 *vertex[4];
	bool connect[4];
	bool disconnected;

	int sn( int i ){ return i < 2 ? i : 5-i; }
	CJoint2(){ for( int i=0; i<4; i++ ) this->vertex[i] = NULL;  disconnected = false; }
	int constructConnect(){ int connectCount = 0; for( int i=0; i<4; i++ ) if( connect[i] = vertex[sn(i)] && vertex[sn((i+1)%4)] ) connectCount++; return connectCount; }
	int disconnect( double threshold );
	void adjustAcceleration();
	void adjustAcceleration(int i1, int i2);
	void adjustAcceleration2();
	bool ifConnectAll(){ return int(ifConnect(0))+int(ifConnect(1))+int(ifConnect(2))+int(ifConnect(3)) >= 3; }
	bool ifConnect(int i, int j){ return ifConnect(i) && ifConnect(j); }
	bool ifConnect(int i){ return vertex[sn(i)] && vertex[sn((i+1)%4)] && connect[i]; }
};

class CJoint{
public:
	CVertex *vertex[8];
	bool connect[12];
	bool disconnected;

	int sn1( int i ){ return i<4 ? i*2 : i<8 ? (i-4)*4%7 : i-8; }
	int sn2( int i ){ return i<4 ? i*2+1 : i<8 ? (i-4)*4%7+2 : i-4; }
	CJoint(){ int i; for( i=0; i<8; i++ ) this->vertex[i] = NULL; disconnected = false; }
	int constructConnect(){ int connectCount = 0; for( int i=0; i<12; i++ ) if( connect[i] = vertex[sn1(i)] && vertex[sn2(i)] ) connectCount++; return connectCount; }
	int disconnect( double threshold );
	bool teared(CVertex *v1, CVertex *v2, double threshold ){
		if(v1==NULL || v2==NULL ) return false;
		ogVector a = v1->acceleration - v2->acceleration;
		return  a.abs2() > threshold*threshold;
	}
	void adjustAcceleration();
	bool ifConnectAll(){ return int(ifConnect(0))+int(ifConnect(1))+int(ifConnect(2))+int(ifConnect(3)) >= 3; }
	bool ifConnect(int i, int j){ return ifConnect(i) && ifConnect(j); }
	bool ifConnect(int i){ return vertex[sn1(i)] && vertex[sn2(i)] && connect[i]; }
};

int CJoint2::disconnect( double threshold ){
	for( int i=0; i<4; i++ ){
		if( this->ifConnect(i) && vertex[sn(i)] && vertex[sn((i+1)%4)] && vertex[sn(i)] != vertex[sn((i+1)%4)] ){
//			if( this->ifConnect(i) && vertex[sn(i)] && vertex[sn((i+1)%4)] ){
			ogVector2 a = vertex[sn(i)]->acceleration - vertex[sn((i+1)%4)]->acceleration;
			if( a.abs2() > threshold*threshold ){
				connect[i] = false;
				disconnected = true;
			}
		}
		//if(disconnected) printf("%d ",connect[i] );
	}
	//if(disconnected) printf("\n" );
	return disconnected;
}
int CJoint::disconnect( double threshold ){
	if(disconnected) return disconnected;
	if(teared(vertex[0],vertex[1],threshold)||teared(vertex[2],vertex[3],threshold)||teared(vertex[0],vertex[2],threshold)||teared(vertex[1],vertex[3],threshold)
	|| teared(vertex[4],vertex[5],threshold)||teared(vertex[6],vertex[7],threshold)||teared(vertex[4],vertex[6],threshold)||teared(vertex[5],vertex[7],threshold)
	|| teared(vertex[0],vertex[4],threshold)||teared(vertex[1],vertex[5],threshold)||teared(vertex[2],vertex[6],threshold)||teared(vertex[3],vertex[7],threshold) ){
		disconnected = true;
	}
	return disconnected;
}

void CJoint2::adjustAcceleration(){
	if( disconnected ) return;
	ogVector2 acceleration(0.0, 0.0);
	int count = 0;
	int i;
	for( i=0; i<4; i++ ){
		if( vertex[sn(i%4)] ){
			acceleration += vertex[sn(i%4)]->acceleration;
			count ++;
		}
	}
	acceleration /= count;
	for( i=0; i<4; i++ ) if( vertex[sn(i%4)] ) vertex[sn(i%4)]->acceleration = acceleration;
}
void CJoint::adjustAcceleration(){
	if( disconnected ) return;
	ogVector acceleration(0.0, 0.0,0.0);
	int count = 0;
	int i;
	for( i=0; i<8; i++ ){
		if( vertex[i] ){
			acceleration += vertex[i]->acceleration;
			count ++;
		}
	}
	acceleration /= count;
	for( i=0; i<8; i++ ) if( vertex[i] ) vertex[i]->acceleration = acceleration;
}

void CJoint2::adjustAcceleration(int i1, int i2){
	ogVector2 acceleration(0.0, 0.0);
	int count = 0;
	int i;
	for( i=i1; i<=i2; i++ ){
		if( vertex[sn(i%4)] != vertex[sn((i+3)%4)]){
			acceleration += vertex[sn(i%4)]->acceleration;
			count++;
		}
	}
	acceleration /= count;
	for( i=i1; i<=i2; i++ ) vertex[sn(i%4)]->acceleration = acceleration;
}

void CJoint2::adjustAcceleration2(){
	if( this->ifConnectAll() ){
		this->adjustAcceleration( 0, 3 );
		return;
	}
	int i;
	for(i=0; i<4; i++){
		if( this->ifConnect(i,(i+1)%4) ){
			this->adjustAcceleration( i, i+2 );
			return;
		}
	}
	for(i=0; i<4; i++) if( this->ifConnect(i) ) this->adjustAcceleration( i, i+1 );
}