Claw  1.7.3
line_2d.tpp
1 /*
2  CLAW - a C++ Library Absolutely Wonderful
3 
4  CLAW is a free library without any particular aim but being useful to
5  anyone.
6 
7  Copyright (C) 2005-2011 Julien Jorge
8 
9  This library is free software; you can redistribute it and/or
10  modify it under the terms of the GNU Lesser General Public
11  License as published by the Free Software Foundation; either
12  version 2.1 of the License, or (at your option) any later version.
13 
14  This library is distributed in the hope that it will be useful,
15  but WITHOUT ANY WARRANTY; without even the implied warranty of
16  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  Lesser General Public License for more details.
18 
19  You should have received a copy of the GNU Lesser General Public
20  License along with this library; if not, write to the Free Software
21  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 
23  contact: julien.jorge@gamned.org
24 */
25 /**
26  * \file line_2d.tpp
27  * \brief Implementation of claw::math::line_2d class.
28  * \author Julien Jorge
29  */
30 
31 /*----------------------------------------------------------------------------*/
32 /**
33  * \brief Constructor.
34  */
35 template<class T>
36 claw::math::line_2d<T>::line_2d()
37 {
38 
39 } // line_2d::line_2d() [constructor]
40 
41 /*----------------------------------------------------------------------------*/
42 /**
43  * \brief Constructor.
44  * \param that Line to copy from.
45  */
46 template<class T>
47 template<class U>
48 claw::math::line_2d<T>::line_2d( const line_2d<U>& that )
49  : origin(that.origin), direction(that.direction)
50 {
51 
52 } // line_2d::line_2d() [copy constructor]
53 
54 /*----------------------------------------------------------------------------*/
55 /**
56  * \brief Constructor with initializations.
57  * \param _origin A point on the line.
58  * \param _direction The direction of the line.
59  */
60 template<class T>
61 claw::math::line_2d<T>::line_2d
62 ( const point_type& _origin, const direction_type& _direction )
63  : origin(_origin), direction(_direction)
64 {
65 
66 } // line_2d::line_2d() [constructor with values]
67 
68 /*----------------------------------------------------------------------------*/
69 /**
70  * \brief Constructor with initializations.
71  * \param ox X-coordinate of the origin.
72  * \param oy Y-coordinate of the origin.
73  * \param dx X direction of the line.
74  * \param dy Y direction of the line.
75  */
76 template<class T>
77 claw::math::line_2d<T>::line_2d( const value_type& ox, const value_type& oy,
78  const value_type& dx, const value_type& dy )
79  : origin(ox, oy), direction(dx, dy)
80 {
81 
82 } // line_2d::line_2d() [constructor with detailed origin & direction]
83 
84 /*----------------------------------------------------------------------------*/
85 /**
86  * \brief Tell if two lines are parallels.
87  * \param that The other line.
88  */
89 template<class T>
90 bool claw::math::line_2d<T>::parallel( const self_type& that ) const
91 {
92  return !( (direction.x * that.direction.y)
93  - (that.direction.x * direction.y) );
94 } // line_2d::parallel()
95 
96 /*----------------------------------------------------------------------------*/
97 /**
98  * \brief Tell if two lines are orthogonal.
99  * \param that The other line.
100  */
101 template<class T>
102 bool claw::math::line_2d<T>::orthogonal( const self_type& that ) const
103 {
104  return !( direction.dot_product( that.direction ) );
105 } // line_2d::orthogonal()
106 
107 /*----------------------------------------------------------------------------*/
108 /**
109  * \brief Get the point at the intersection of two lines.
110  * \param that The other line.
111  * \remark The result if unknow if the two lines are parallel.
112  */
113 template<class T>
114 typename claw::math::line_2d<T>::point_type
115 claw::math::line_2d<T>::intersection( const self_type& that ) const
116 {
117  point_type result;
118 
119  if ( ! parallel( that ) )
120  {
121  point_type delta( that.origin - origin );
122  value_type n, m;
123 
124  n = direction.x * delta.y - direction.y * delta.x;
125  m = that.direction.x * direction.y - direction.x * that.direction.y;
126 
127  result.x = that.origin.x + (n * that.direction.x) / m;
128  result.y = that.origin.y + (n * that.direction.y) / m;
129  }
130 
131  return result;
132 } // line_2d::intersection()
133 
134 /*----------------------------------------------------------------------------*/
135 /**
136  * \brief Get the y value of the point of the line at position \a x.
137  * \param x The X-coordinate for which we want the Y-coordinate.
138  */
139 template<class T>
140 typename claw::math::line_2d<T>::value_type
141 claw::math::line_2d<T>::y_value( const value_type& x ) const
142 {
143  return (direction.y * (x - origin.x) + direction.x * origin.y) / direction.x;
144 } // line_2d::y_value()