Triangle constructor
Implementation
Triangle( this.v1, this.v2, this.v3, this.a, this.b, this.c ) {
computeNormal();
v1?.faces.add( this );
v1?.addUniqueNeighbor( v2 );
v1?.addUniqueNeighbor( v3 );
v2?.faces.add( this );
v2?.addUniqueNeighbor( v1 );
v2?.addUniqueNeighbor( v3 );
v3?.faces.add( this );
v3?.addUniqueNeighbor( v1 );
v3?.addUniqueNeighbor( v2 );
}