Line data Source code
1 : /* Copyright (C) 2011 Wildfire Games.
2 : * This file is part of 0 A.D.
3 : *
4 : * 0 A.D. is free software: you can redistribute it and/or modify
5 : * it under the terms of the GNU General Public License as published by
6 : * the Free Software Foundation, either version 2 of the License, or
7 : * (at your option) any later version.
8 : *
9 : * 0 A.D. is distributed in the hope that it will be useful,
10 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 : * GNU General Public License for more details.
13 : *
14 : * You should have received a copy of the GNU General Public License
15 : * along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
16 : */
17 :
18 : #ifndef INCLUDED_BOX
19 : #define INCLUDED_BOX
20 :
21 : #include "maths/Vector3D.h"
22 :
23 : class CBoundingBoxAligned;
24 :
25 : /*
26 : * Generic oriented box. Originally intended to be used an Oriented Bounding Box (OBB),
27 : * as opposed to CBoundingBoxAligned which is always aligned to the world-space axes (AABB).
28 : * However, it could also be used to represent more generic shapes, such as parallelepipeds.
29 : */
30 : class CBoundingBoxOriented
31 : {
32 : public:
33 :
34 : /// Empty constructor; creates an empty box
35 8 : CBoundingBoxOriented() { SetEmpty(); }
36 :
37 : /**
38 : * Constructs a new oriented box centered at @p center and with normalized side vectors @p u,
39 : * @p v and @p w. These vectors should be mutually orthonormal for a proper rectangular box.
40 : * The half-widths of the box in each dimension are given by the corresponding components of
41 : * @p halfSizes.
42 : */
43 : CBoundingBoxOriented(const CVector3D& center, const CVector3D& u, const CVector3D& v, const CVector3D& w, const CVector3D& halfSizes)
44 : : m_Center(center), m_HalfSizes(halfSizes)
45 : {
46 : m_Basis[0] = u;
47 : m_Basis[1] = v;
48 : m_Basis[2] = w;
49 : }
50 :
51 : /// Constructs a new box from an axis-aligned bounding box (AABB).
52 : explicit CBoundingBoxOriented(const CBoundingBoxAligned& bound);
53 :
54 : /**
55 : * Check if a given ray intersects this box. Must not be used if IsEmpty() is true.
56 : * See Real-Time Rendering, Third Edition by T. Akenine-Moller, p. 741--744.
57 : *
58 : * @param[in] origin Origin of the ray.
59 : * @param[in] dir Direction vector of the ray, defining the positive direction of the ray.
60 : * Must be of unit length.
61 : * @param[out] tMin,tMax Distance in the positive direction from the origin of the ray to the
62 : * entry and exit points in the box, provided that the ray intersects the box. if
63 : * the ray does not intersect the box, no values are written to these variables.
64 : * If the origin is inside the box, then this is counted as an intersection and one
65 : * of @p tMin and @p tMax may be negative.
66 : *
67 : * @return true If the ray originating in @p origin and with unit direction vector @p dir intersects
68 : * this box, false otherwise.
69 : */
70 : bool RayIntersect(const CVector3D& origin, const CVector3D& dir, float& tMin, float& tMax) const;
71 :
72 : /**
73 : * Returns the corner at coordinate (@p u, @p v, @p w). Each of @p u, @p v and @p w must be exactly 1 or -1.
74 : * Must not be used if IsEmpty() is true.
75 : */
76 0 : void GetCorner(int u, int v, int w, CVector3D& out) const
77 : {
78 0 : out = m_Center + m_Basis[0]*(u*m_HalfSizes[0]) + m_Basis[1]*(v*m_HalfSizes[1]) + m_Basis[2]*(w*m_HalfSizes[2]);
79 0 : }
80 :
81 9 : void SetEmpty()
82 : {
83 : // everything is zero
84 9 : m_Center = CVector3D();
85 9 : m_Basis[0] = CVector3D();
86 9 : m_Basis[1] = CVector3D();
87 9 : m_Basis[2] = CVector3D();
88 9 : m_HalfSizes = CVector3D();
89 9 : }
90 :
91 3 : bool IsEmpty() const
92 : {
93 3 : CVector3D empty;
94 6 : return (m_Center == empty &&
95 5 : m_Basis[0] == empty &&
96 4 : m_Basis[1] == empty &&
97 7 : m_Basis[2] == empty &&
98 5 : m_HalfSizes == empty);
99 : }
100 :
101 : public:
102 : CVector3D m_Center; ///< Centroid location of the box
103 : CVector3D m_HalfSizes; ///< Half the sizes of the box in each dimension (u,v,w). Positive values are expected.
104 : /// Basis vectors (u,v,w) of the sides. Must always be normalized, and should be
105 : /// orthogonal for a proper rectangular cuboid.
106 : CVector3D m_Basis[3];
107 :
108 : static const CBoundingBoxOriented EMPTY;
109 : };
110 :
111 : #endif // INCLUDED_BOX
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