Line data    Source code

       1             : //* This file is part of the MOOSE framework
       2             : //* https://mooseframework.inl.gov
       3             : //*
       4             : //* All rights reserved, see COPYRIGHT for full restrictions
       5             : //* https://github.com/idaholab/moose/blob/master/COPYRIGHT
       6             : //*
       7             : //* Licensed under LGPL 2.1, please see LICENSE for details
       8             : //* https://www.gnu.org/licenses/lgpl-2.1.html
       9             : 
      10             : #include "Triangle.h"
      11             : #include "LineSegment.h"
      12             : 
      13             : #include <cmath>
      14             : 
      15             : using libMesh::Point;
      16             : using libMesh::Real;
      17             : 
      18           0 : Triangle::Triangle(const Point & p0, const Point & p1, const Point & p2) : _p0(p0), _p1(p1), _p2(p2)
      19             : {
      20           0 : }
      21             : 
      22             : Point
      23           0 : Triangle::normal() const
      24             : {
      25           0 :   const auto v1 = _p1 - _p0;
      26           0 :   const auto v2 = _p2 - _p0;
      27             : 
      28           0 :   auto n = v1.cross(v2);
      29           0 :   n /= n.norm();
      30             : 
      31           0 :   return n;
      32             : }
      33             : 
      34             : bool
      35           0 : Triangle::intersect(const LineSegment & line_segment, Point & intersect_p) const
      36             : {
      37           0 :   const auto & a = line_segment.start();
      38           0 :   const auto & b = line_segment.end();
      39             : 
      40             :   // (a) Build basic vectors and choose a robust tolerance
      41           0 :   const Point dir = b - a;
      42             : 
      43           0 :   const Point edge1 = _p1 - _p0;
      44           0 :   const Point edge2 = _p2 - _p0;
      45           0 :   constexpr Real eps = libMesh::TOLERANCE;
      46             : 
      47             :   // (b) Test for parallel or degenerate configuration
      48           0 :   const Point pvec = dir.cross(edge2);
      49           0 :   const Real det = edge1 * pvec;
      50           0 :   if (std::abs(det) < eps)
      51           0 :     return false; // ray nearly parallel to triangle
      52             : 
      53           0 :   const Real inv_det = 1.0 / det;
      54             : 
      55             :   // (c) Compute barycentric coordinate u and check 0 <= u <= 1
      56           0 :   const Point tvec = a - _p0;
      57           0 :   const Real u = (tvec * pvec) * inv_det;
      58           0 :   if (!MooseUtils::absoluteFuzzyGreaterEqual(u, 0.0, eps) ||
      59           0 :       !MooseUtils::absoluteFuzzyLessEqual(u, 1.0, eps))
      60           0 :     return false;
      61             : 
      62             :   // (d) Compute barycentric coordinate v and check 0 <= v and u + v <= 1
      63           0 :   const Point qvec = tvec.cross(edge1);
      64           0 :   const Real v = (dir * qvec) * inv_det;
      65           0 :   if (!MooseUtils::absoluteFuzzyGreaterEqual(v, 0.0, eps) ||
      66           0 :       !MooseUtils::absoluteFuzzyLessEqual(u + v, 1.0, eps))
      67           0 :     return false;
      68             : 
      69             :   // (e) Locate intersection along line segment (0 <= t <= 1 constrains to a--b)
      70           0 :   const Real t = (edge2 * qvec) * inv_det;
      71           0 :   if (!MooseUtils::absoluteFuzzyGreaterEqual(t, 0.0, eps) ||
      72           0 :       !MooseUtils::absoluteFuzzyLessEqual(t, 1.0, eps))
      73           0 :     return false;
      74             : 
      75             :   // (f) Intersection lies inside both the triangle and the segment
      76           0 :   intersect_p = a + dir * t;
      77           0 :   return true;
      78             : }
      79             : 
      80             : bool
      81           0 : Triangle::intersect(const LineSegment & line_segment) const
      82             : {
      83           0 :   libMesh::Point p;
      84           0 :   return intersect(line_segment, p);
      85             : }
      86             : 
      87             : Ball
      88           0 : Triangle::computeBoundingBall() const
      89             : {
      90           0 :   const Point centroid = (_p0 + _p1 + _p2) / 3.0;
      91             : 
      92           0 :   Real max_sq_dist = 0.0;
      93           0 :   for (const auto * p : {&_p0, &_p1, &_p2})
      94             :   {
      95           0 :     const Real dist_sq = (*p - centroid).norm_sq();
      96           0 :     if (dist_sq > max_sq_dist)
      97           0 :       max_sq_dist = dist_sq;
      98             :   }
      99             : 
     100           0 :   const Real radius = std::sqrt(max_sq_dist);
     101           0 :   return Ball(centroid, radius);
     102             : }