/usr/include/dolfin/geometry/IntersectionConstruction.h is in libdolfin-dev 2017.2.0.post0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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//
// This file is part of DOLFIN.
//
// DOLFIN is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// DOLFIN is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with DOLFIN. If not, see <http://www.gnu.org/licenses/>.
//
// First added: 2014-02-03
// Last changed: 2017-09-29
#ifndef __INTERSECTION_CONSTRUCTION_H
#define __INTERSECTION_CONSTRUCTION_H
#include <vector>
#include <dolfin/log/log.h>
#include "Point.h"
namespace dolfin
{
// Forward declarations
class MeshEntity;
/// This class implements algorithms for computing pairwise
/// intersections of simplices. The computed intersection is always
/// convex and represented as a set of points s.t. the intersection
/// is the convex hull of these points.
class IntersectionConstruction
{
public:
/// Compute intersection of two entities.
///
/// *Arguments*
/// entity_0 (_MeshEntity_)
/// The first entity.
/// entity_1 (_MeshEntity_)
/// The second entity.
///
/// *Returns*
/// std::vector<Pointdouble>
/// A vector of points s.t. the intersection is the convex hull of
/// these points.
static std::vector<Point>
intersection(const MeshEntity& entity_0,
const MeshEntity& entity_1);
/// Compute intersection of two entities.
/// This version takes two vectors of points representing the entities.
///
/// *Arguments*
/// points_0 (std::vector<Point>)
/// The vertex coordinates of the first entity.
/// points_1 (std::vector<Point>)
/// The vertex coordinates of the second entity.
/// gdim (std::size_t)
/// The geometric dimension.
///
/// *Returns*
/// std::vector<Point>
/// A vector of points s.t. the intersection is the convex hull of
/// these points.
static std::vector<Point>
intersection(const std::vector<Point>& points_0,
const std::vector<Point>& points_1,
std::size_t gdim);
//--- Low-level intersection construction functions ---
// There are 19 different intersections to consider. Initially, we have
// 4 different entities: point, segment, triangle, tetrahedron, and thus
// 16 combinations. Because of symmetry, these are reduced to 10. However,
// some of the combination are relevant in both 1D, 2D and 3D, and thus
// the total number of intersections lands at 19. The table indicates the
// number of versions (1D, 2D, 3D) for each relevant combination.
//
// | 0 1 2 3
// --------------
// 0 | 3 x x x point-foo (1D, 2D, 3D)
// 1 | 3 3 x x segment-foo (1D, 2D, 3D)
// 2 | 2 2 2 x triangle-foo (--, 2D, 3D)
// 3 | 1 1 1 1 tetrahedron-foo (--, --, 3D)
//
// The intersection construction functions can be grouped into
// three classes:
//
// [P] Use point collision predicates (9)
// [C] Compute collision by solving for intersection points (3)
// [D] Delegate computation to [P] or [C] for subsimplices (7)
//
// [P] intersection_point_point_1d
// [P] intersection_point_point_2d
// [P] intersection_point_point_3d
// [P] intersection_segment_point_1d
// [P] intersection_segment_point_2d
// [P] intersection_segment_point_3d
// [P] intersection_triangle_point_2d
// [P] intersection_triangle_point_3d
// [P] intersection_tetrahedron_point_3d
// [D] intersection_segment_segment_1d
// [C] intersection_segment_segment_2d
// [C] intersection_segment_segment_3d <-- not used/implemented
// [D] intersection_triangle_segment_2d
// [C] intersection_triangle_segment_3d <-- needs review
// [D] intersection_tetrahedron_segment_3d
// [D] intersection_triangle_triangle_2d
// [D] intersection_triangle_triangle_3d
// [D] intersection_tetrahedron_triangle_3d
// [D] intersection_tetrahedron_tetrahedron_3d
//
// Note that intersection_segment_segment_3d is not used/implemented.
// In summary, this means that there are only two functions that require
// computation, other than simple checks for point collisions or delegation
// to lower-level intersection functions. These two functions are:
//
// [C] intersection_segment_segment_2d
// [C] intersection_triangle_segment_3d
/// Compute intersection of points p0 and q0 (1D)
static std::vector<double>
intersection_point_point_1d(double p0,
double q0);
/// Compute intersection of points p0 and q0 (2D)
static std::vector<Point>
intersection_point_point_2d(const Point& p0,
const Point& q0);
/// Compute intersection of points p0 and q0 (3D)
static std::vector<Point>
intersection_point_point_3d(const Point& p0,
const Point& q0);
/// Compute intersection of segment p0-p1 with point q0 (1D)
static std::vector<double>
intersection_segment_point_1d(double p0,
double p1,
double q0);
/// Compute intersection of segment p0-p1 with point q0 (2D)
static std::vector<Point>
intersection_segment_point_2d(const Point& p0,
const Point& p1,
const Point& q0);
/// Compute intersection of segment p0-p1 with point q0 (3D)
static std::vector<Point>
intersection_segment_point_3d(const Point& p0,
const Point& p1,
const Point& q0);
/// Compute intersection of triangle p0-p1-p2 with point q0 (2D)
static std::vector<Point>
intersection_triangle_point_2d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0);
/// Compute intersection of triangle p0-p1-p2 with point q0 (3D)
static std::vector<Point>
intersection_triangle_point_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0);
/// Compute intersection of tetrahedron p0-p1-p2-p3 with point q0 (3D)
static std::vector<Point>
intersection_tetrahedron_point_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& p3,
const Point& q0);
/// Compute intersection of segment p0-p1 with segment q0-q1 (1D)
static std::vector<double>
intersection_segment_segment_1d(double p0,
double p1,
double q0,
double q1);
/// Compute intersection of segment p0-p1 with segment q0-q1 (2D)
static std::vector<Point>
intersection_segment_segment_2d(const Point& p0,
const Point& p1,
const Point& q0,
const Point& q1);
/// Compute intersection of segment p0-p1 with segment q0-q1 (3D)
static std::vector<Point>
intersection_segment_segment_3d(const Point& p0,
const Point& p1,
const Point& q0,
const Point& q1);
/// Compute intersection of triangle p0-p1-p2 with segment q0-q1 (2D)
static std::vector<Point>
intersection_triangle_segment_2d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0,
const Point& q1);
/// Compute intersection of triangle p0-p1-p2 with segment q0-q1 (3D)
static std::vector<Point>
intersection_triangle_segment_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0,
const Point& q1);
/// Compute intersection of tetrahedron p0-p1-p2-p3 with segment q0-q1 (3D)
static std::vector<Point>
intersection_tetrahedron_segment_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& p3,
const Point& q0,
const Point& q1);
/// Compute intersection of triangle p0-p1-p2 with triangle q0-q1-q2 (2D)
static std::vector<Point>
intersection_triangle_triangle_2d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0,
const Point& q1,
const Point& q2);
/// Compute intersection of triangle p0-p1-p2 with triangle q0-q1-q2 (3D)
static std::vector<Point>
intersection_triangle_triangle_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0,
const Point& q1,
const Point& q2);
/// Compute intersection of tetrahedron p0-p1-p2-p3 with triangle q0-q1-q2 (3D)
static std::vector<Point>
intersection_tetrahedron_triangle_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& p3,
const Point& q0,
const Point& q1,
const Point& q2);
/// Compute intersection of tetrahedron p0-p1-p2-p3 with tetrahedron q0-q1-q2-q3 (3D)
static std::vector<Point>
intersection_tetrahedron_tetrahedron_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& p3,
const Point& q0,
const Point& q1,
const Point& q2,
const Point& q3);
private :
/// Compute intersection of triangle p0-p1-p2 with segment q0-q1 (3D)
static std::vector<Point>
_intersection_triangle_segment_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& q0,
const Point& q1);
static std::vector<Point>
_intersection_tetrahedron_tetrahedron_3d(const Point& p0,
const Point& p1,
const Point& p2,
const Point& p3,
const Point& q0,
const Point& q1,
const Point& q2,
const Point& q3);
};
}
#endif
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