# Facet A Facet facet is essentially any triangle with a normal, as defined in Euclid. The triangle may be made up of points,or it can be an IndexTriangle. In that case, it does not contain the points itself, but numbers that are assumed to identify points in an external data structure.
    template <class Triangle, typename T>
    class Facet : public Triangle;
Note: As Facet inherits from Triangle, accessing the points of the Facet is the same as accessing points of the Triangle. ## Interface
    value_type
| The type used for the normals, i.e. template parameter "T".
    triange_type
| The triangle type, i.e. template parameter "Triangle".
    normal_type
| The type of the normal, which is a kind of Vector.
    const_triangle_iterator
| Read-only iterator of the triangle_type.
    normal_iterator
| Iterator of the normal_type.
    const_normal_iterator
| Read-only Iterator of the const_normal_type.
    Facet()
| Default Constructor.
    Facet(const const_triangle_iterator first,
    	const const_triangle_iterator last)
| A Constructor that enters values into the Triangle.
    Facet(const const_triangle_iterator first,
    	const const_triangle_iterator last,
    	const_normal_iterator normalFirst,
    	const_normal_iterator normalLast)
| A Constructor that enters values into the Triangle and the Normal.
    template <typename It>
    void set(It first, It last, const normal_type &normal)
| Copy points from range first ... last, copy normal.
    const normal_type &normal() const
| Returns a refence for read-only use.
    normal_type &normal()
| Returns a reference to the normal.