Primitives

Primal includes the following primitives:

  • Point

  • Segment, Ray, Vector

  • Plane, Triangle, Polygon

  • Quadrilateral

  • Sphere

  • Tetrahedron

  • Hexahedron

  • BoundingBox, OrientedBoundingBox

  • Polyhedron

Note

Primitives in Axom use a right-handed coordinate system.

Primal also provides the NumericArray class, which implements arithmetic operations on numerical tuples and supports Primal’s Point and Vector classes. Classes in Primal are templated on coordinate type (double, float, etc.) and dimension. The primitives do not inherit from a common base class. This was a design choice in favor of simplicity and performance. Geometric primitives can be tested for equality and can be printed to strings.

Primal also includes functions to merge a pair of BoundingBox or a pair of OrientedBoundingBox objects and to create new OrientedBoundingBox objects from a list of points.

The following includes header files for primal’s primitives as well as some using directives and typedef statements that will be used in the examples. Header files for operations will be shown next to code examples. Although the examples #include separate class header files, it is easier and less error-prone to write #include axom/primal.hpp.

// Axom primitives
#include "axom/primal/geometry/BoundingBox.hpp"
#include "axom/primal/geometry/OrientedBoundingBox.hpp"
#include "axom/primal/geometry/Point.hpp"
#include "axom/primal/geometry/Polygon.hpp"
#include "axom/primal/geometry/Ray.hpp"
#include "axom/primal/geometry/Segment.hpp"
#include "axom/primal/geometry/Triangle.hpp"
#include "axom/primal/geometry/Vector.hpp"

// "using" directives to simplify code
namespace primal = axom::primal;

// almost all our examples are in 3D
constexpr int in3D = 3;

// primitives represented by doubles in 3D
using PointType = primal::Point<double, in3D>;
using TriangleType = primal::Triangle<double, in3D>;
using BoundingBoxType = primal::BoundingBox<double, in3D>;
using OrientedBoundingBoxType = primal::OrientedBoundingBox<double, in3D>;
using PolygonType = primal::Polygon<double, in3D>;
using RayType = primal::Ray<double, in3D>;
using SegmentType = primal::Segment<double, in3D>;
using VectorType = primal::Vector<double, in3D>;