1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
/*
* Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
#include "Box2D/Collision/Shapes/b2EdgeShape.h"
#include <new>
void b2EdgeShape::Set(const b2Vec2& v1, const b2Vec2& v2)
{
m_vertex1 = v1;
m_vertex2 = v2;
m_hasVertex0 = false;
m_hasVertex3 = false;
}
b2Shape* b2EdgeShape::Clone(b2BlockAllocator* allocator) const
{
void* mem = allocator->Allocate(sizeof(b2EdgeShape));
b2EdgeShape* clone = new (mem) b2EdgeShape;
*clone = *this;
return clone;
}
int32 b2EdgeShape::GetChildCount() const
{
return 1;
}
bool b2EdgeShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
{
B2_NOT_USED(xf);
B2_NOT_USED(p);
return false;
}
// p = p1 + t * d
// v = v1 + s * e
// p1 + t * d = v1 + s * e
// s * e - t * d = p1 - v1
bool b2EdgeShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
// Put the ray into the edge's frame of reference.
b2Vec2 p1 = b2MulT(xf.q, input.p1 - xf.p);
b2Vec2 p2 = b2MulT(xf.q, input.p2 - xf.p);
b2Vec2 d = p2 - p1;
b2Vec2 v1 = m_vertex1;
b2Vec2 v2 = m_vertex2;
b2Vec2 e = v2 - v1;
b2Vec2 normal(e.y, -e.x);
normal.Normalize();
// q = p1 + t * d
// dot(normal, q - v1) = 0
// dot(normal, p1 - v1) + t * dot(normal, d) = 0
float32 numerator = b2Dot(normal, v1 - p1);
float32 denominator = b2Dot(normal, d);
if (denominator == 0.0f)
{
return false;
}
float32 t = numerator / denominator;
if (t < 0.0f || input.maxFraction < t)
{
return false;
}
b2Vec2 q = p1 + t * d;
// q = v1 + s * r
// s = dot(q - v1, r) / dot(r, r)
b2Vec2 r = v2 - v1;
float32 rr = b2Dot(r, r);
if (rr == 0.0f)
{
return false;
}
float32 s = b2Dot(q - v1, r) / rr;
if (s < 0.0f || 1.0f < s)
{
return false;
}
output->fraction = t;
if (numerator > 0.0f)
{
output->normal = -b2Mul(xf.q, normal);
}
else
{
output->normal = b2Mul(xf.q, normal);
}
return true;
}
void b2EdgeShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
{
B2_NOT_USED(childIndex);
b2Vec2 v1 = b2Mul(xf, m_vertex1);
b2Vec2 v2 = b2Mul(xf, m_vertex2);
b2Vec2 lower = b2Min(v1, v2);
b2Vec2 upper = b2Max(v1, v2);
b2Vec2 r(m_radius, m_radius);
aabb->lowerBound = lower - r;
aabb->upperBound = upper + r;
}
void b2EdgeShape::ComputeMass(b2MassData* massData, float32 density) const
{
B2_NOT_USED(density);
massData->mass = 0.0f;
massData->center = 0.5f * (m_vertex1 + m_vertex2);
massData->I = 0.0f;
}
|
