overlaps_alignedplane_triangle.hpp

#ifndef PASTELGEOMETRY_OVERLAPS_ALIGNEDPLANE_TRIANGLE_HPP
#define PASTELGEOMETRY_OVERLAPS_ALIGNEDPLANE_TRIANGLE_HPP

#include "pastel/geometry/overlap/overlaps_alignedplane_triangle.h"

#include "pastel/geometry/shape/alignedplane.h"
#include "pastel/geometry/shape/triangle.h"

namespace Pastel
{

    template <typename Real, integer N>
    bool overlaps(
        const AlignedPlane<Real, N>& plane,
        const PASTEL_TRIANGLE(Real, N)& triangle)
    {
        // There is an intersection if two points of the triangle
        // are located at different sides of AlignedPlane or any of
        // the points are on the plane.

        // EPSILON
        if (plane.position() - triangle[0][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        // EPSILON
        if (plane.position() - triangle[1][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        // EPSILON
        if (plane.position() - triangle[2][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        bool aSide = (plane.position() > triangle[0][plane.axis()]);
        bool bSide = (plane.position() > triangle[1][plane.axis()]);
        bool cSide = (plane.position() > triangle[2][plane.axis()]);

        return ((aSide != bSide) || (aSide != cSide));
    }

    template <typename Real, integer N>
    bool overlaps(
        const AlignedPlane<Real, N>& plane,
        const PASTEL_TRIANGLE(Real, N)& triangle,
        bool &triangleOnPositiveSide)
    {
        // There is an intersection if two points of the triangle
        // are located at different sides of AlignedPlane or any of
        // the points are on the plane.

        // EPSILON
        if (plane.position() - triangle[0][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        // EPSILON
        if (plane.position() - triangle[1][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        // EPSILON
        if (plane.position() - triangle[2][plane.axis()] == 0)
        {
            // There is a point on the plane.

            return true;
        }

        bool aSide = (plane.position() > triangle[0][plane.axis()]);
        bool bSide = (plane.position() > triangle[1][plane.axis()]);
        bool cSide = (plane.position() > triangle[2][plane.axis()]);

        triangleOnPositiveSide = aSide;

        return ((aSide != bSide) || (aSide != cSide));
    }

}

#endif