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// David Eberly, Geometric Tools, Redmond WA 98052
// Copyright (c) 1998-2021
// Distributed under the Boost Software License, Version 1.0.
// https://www.boost.org/LICENSE_1_0.txt
// https://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
// Version: 4.0.2019.08.13
#pragma once
#include <Mathematics/IntrAlignedBox2Circle2.h>
#include <Mathematics/DistPointOrientedBox.h>
// The find-intersection query is based on the document
// https://www.geometrictools.com/Documentation/IntersectionMovingCircleRectangle.pdf
namespace gte
{
template <typename Real>
class TIQuery<Real, OrientedBox2<Real>, Circle2<Real>>
{
public:
// The intersection query considers the box and circle to be solids;
// that is, the circle object includes the region inside the circular
// boundary and the box object includes the region inside the
// rectangular boundary. If the circle object and rectangle object
// overlap, the objects intersect.
struct Result
{
bool intersect;
};
Result operator()(OrientedBox2<Real> const& box, Circle2<Real> const& circle)
{
DCPQuery<Real, Vector2<Real>, OrientedBox2<Real>> pbQuery;
auto pbResult = pbQuery(circle.center, box);
Result result;
result.intersect = (pbResult.sqrDistance <= circle.radius * circle.radius);
return result;
}
};
template <typename Real>
class FIQuery<Real, OrientedBox2<Real>, Circle2<Real>>
:
public FIQuery<Real, AlignedBox2<Real>, Circle2<Real>>
{
public:
// See the base class for the definition of 'struct Result'.
typename FIQuery<Real, AlignedBox2<Real>, Circle2<Real>>::Result
operator()(OrientedBox2<Real> const& box, Vector2<Real> const& boxVelocity,
Circle2<Real> const& circle, Vector2<Real> const& circleVelocity)
{
// Transform the oriented box to an axis-aligned box centered at
// the origin and transform the circle accordingly. Compute the
// velocity of the circle relative to the box.
Real const zero(0), one(1), minusOne(-1);
Vector2<Real> cdiff = circle.center - box.center;
Vector2<Real> vdiff = circleVelocity - boxVelocity;
Vector2<Real> C, V;
for (int i = 0; i < 2; ++i)
{
C[i] = Dot(cdiff, box.axis[i]);
V[i] = Dot(vdiff, box.axis[i]);
}
// Change signs on components, if necessary, to transform C to the
// first quadrant. Adjust the velocity accordingly.
Real sign[2];
for (int i = 0; i < 2; ++i)
{
if (C[i] >= zero)
{
sign[i] = one;
}
else
{
C[i] = -C[i];
V[i] = -V[i];
sign[i] = minusOne;
}
}
typename FIQuery<Real, AlignedBox2<Real>, Circle2<Real>>::Result result = { 0, zero, { zero, zero } };
this->DoQuery(box.extent, C, circle.radius, V, result);
if (result.intersectionType != 0)
{
// Transform back to the original coordinate system.
result.contactPoint = box.center
+ (sign[0] * result.contactPoint[0]) * box.axis[0]
+ (sign[1] * result.contactPoint[1]) * box.axis[1];
}
return result;
}
};
}