GteIntrRay3Plane3.h

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// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2017
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// File Version: 3.0.0 (2016/06/19)

#pragma once

#include <Mathematics/GteRay.h>
#include <Mathematics/GteIntrLine3Plane3.h>

namespace gte
{

template <typename Real>
class TIQuery<Real, Ray3<Real>, Plane3<Real>>
{
public:
    struct Result
    {
        bool intersect;
    };

    Result operator()(Ray3<Real> const& ray, Plane3<Real> const& plane);
};

template <typename Real>
class FIQuery<Real, Ray3<Real>, Plane3<Real>>
    :
    public FIQuery<Real, Line3<Real>, Plane3<Real>>
{
public:
    struct Result
        :
        public FIQuery<Real, Line3<Real>, Plane3<Real>>::Result
    {
        // No additional information to compute.
    };

    Result operator()(Ray3<Real> const& ray, Plane3<Real> const& plane);

protected:
    void DoQuery(Vector3<Real> const& rayOrigin,
        Vector3<Real> const& rayDirection, Plane3<Real> const& plane,
        Result& result);
};


template <typename Real>
typename TIQuery<Real, Ray3<Real>, Plane3<Real>>::Result
TIQuery<Real, Ray3<Real>, Plane3<Real>>::operator()(
    Ray3<Real> const& ray, Plane3<Real> const& plane)
{
    Result result;

    // Compute the (signed) distance from the ray origin to the plane.
    DCPQuery<Real, Vector3<Real>, Plane3<Real>> vpQuery;
    auto vpResult = vpQuery(ray.origin, plane);

    Real DdN = Dot(ray.direction, plane.normal);
    if (DdN > (Real)0)
    {
        // The ray is not parallel to the plane and is directed toward the
        // +normal side of the plane.
        result.intersect = (vpResult.signedDistance <= (Real)0);
    }
    else if (DdN < (Real)0)
    {
        // The ray is not parallel to the plane and is directed toward the
        // -normal side of the plane.
        result.intersect = (vpResult.signedDistance >= (Real)0);
    }
    else
    {
        // The ray and plane are parallel.
        result.intersect = (vpResult.distance == (Real)0);
    }

    return result;
}

template <typename Real>
typename FIQuery<Real, Ray3<Real>, Plane3<Real>>::Result
FIQuery<Real, Ray3<Real>, Plane3<Real>>::operator()(
    Ray3<Real> const& ray, Plane3<Real> const& plane)
{
    Result result;
    DoQuery(ray.origin, ray.direction, plane, result);
    if (result.intersect)
    {
        result.point = ray.origin + result.parameter * ray.direction;
    }
    return result;
}

template <typename Real>
void FIQuery<Real, Ray3<Real>, Plane3<Real>>::DoQuery(
    Vector3<Real> const& rayOrigin, Vector3<Real> const& rayDirection,
    Plane3<Real> const& plane, Result& result)
{
    FIQuery<Real, Line3<Real>, Plane3<Real>>::DoQuery(rayOrigin,
        rayDirection, plane, result);
    if (result.intersect)
    {
        // The line intersects the plane in a point that might not be on the
        // ray.
        if (result.parameter < (Real)0)
        {
            result.intersect = false;
            result.numIntersections = 0;
        }
    }
}


}