1 /*
2 * Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
3 *
4 * This software is provided 'as-is', without any express or implied
5 * warranty. In no event will the authors be held liable for any damages
6 * arising from the use of this software.
7 * Permission is granted to anyone to use this software for any purpose,
8 * including commercial applications, and to alter it and redistribute it
9 * freely, subject to the following restrictions:
10 * 1. The origin of this software must not be misrepresented; you must not
11 * claim that you wrote the original software. If you use this software
12 * in a product, an acknowledgment in the product documentation would be
13 * appreciated but is not required.
14 * 2. Altered source versions must be plainly marked as such, and must not be
15 * misrepresented as being the original software.
16 * 3. This notice may not be removed or altered from any source distribution.
17 */
18
19 #include <Box2D/Collision/Shapes/b2ChainShape.h>
20 #include <Box2D/Collision/Shapes/b2EdgeShape.h>
21 #include <new>
22 #include <string.h>
23
~b2ChainShape()24 b2ChainShape::~b2ChainShape()
25 {
26 Clear();
27 }
28
Clear()29 void b2ChainShape::Clear()
30 {
31 b2Free(m_vertices);
32 m_vertices = NULL;
33 m_count = 0;
34 }
35
CreateLoop(const b2Vec2 * vertices,int32 count)36 void b2ChainShape::CreateLoop(const b2Vec2* vertices, int32 count)
37 {
38 b2Assert(m_vertices == NULL && m_count == 0);
39 b2Assert(count >= 3);
40 for (int32 i = 1; i < count; ++i)
41 {
42 b2Vec2 v1 = vertices[i-1];
43 b2Vec2 v2 = vertices[i];
44 // If the code crashes here, it means your vertices are too close together.
45 b2Assert(b2DistanceSquared(v1, v2) > b2_linearSlop * b2_linearSlop);
46 }
47
48 m_count = count + 1;
49 m_vertices = (b2Vec2*)b2Alloc(m_count * sizeof(b2Vec2));
50 memcpy(m_vertices, vertices, count * sizeof(b2Vec2));
51 m_vertices[count] = m_vertices[0];
52 m_prevVertex = m_vertices[m_count - 2];
53 m_nextVertex = m_vertices[1];
54 m_hasPrevVertex = true;
55 m_hasNextVertex = true;
56 }
57
CreateChain(const b2Vec2 * vertices,int32 count)58 void b2ChainShape::CreateChain(const b2Vec2* vertices, int32 count)
59 {
60 b2Assert(m_vertices == NULL && m_count == 0);
61 b2Assert(count >= 2);
62 for (int32 i = 1; i < count; ++i)
63 {
64 // If the code crashes here, it means your vertices are too close together.
65 b2Assert(b2DistanceSquared(vertices[i-1], vertices[i]) > b2_linearSlop * b2_linearSlop);
66 }
67
68 m_count = count;
69 m_vertices = (b2Vec2*)b2Alloc(count * sizeof(b2Vec2));
70 memcpy(m_vertices, vertices, m_count * sizeof(b2Vec2));
71
72 m_hasPrevVertex = false;
73 m_hasNextVertex = false;
74
75 m_prevVertex.SetZero();
76 m_nextVertex.SetZero();
77 }
78
SetPrevVertex(const b2Vec2 & prevVertex)79 void b2ChainShape::SetPrevVertex(const b2Vec2& prevVertex)
80 {
81 m_prevVertex = prevVertex;
82 m_hasPrevVertex = true;
83 }
84
SetNextVertex(const b2Vec2 & nextVertex)85 void b2ChainShape::SetNextVertex(const b2Vec2& nextVertex)
86 {
87 m_nextVertex = nextVertex;
88 m_hasNextVertex = true;
89 }
90
Clone(b2BlockAllocator * allocator) const91 b2Shape* b2ChainShape::Clone(b2BlockAllocator* allocator) const
92 {
93 void* mem = allocator->Allocate(sizeof(b2ChainShape));
94 b2ChainShape* clone = new (mem) b2ChainShape;
95 clone->CreateChain(m_vertices, m_count);
96 clone->m_prevVertex = m_prevVertex;
97 clone->m_nextVertex = m_nextVertex;
98 clone->m_hasPrevVertex = m_hasPrevVertex;
99 clone->m_hasNextVertex = m_hasNextVertex;
100 return clone;
101 }
102
GetChildCount() const103 int32 b2ChainShape::GetChildCount() const
104 {
105 // edge count = vertex count - 1
106 return m_count - 1;
107 }
108
GetChildEdge(b2EdgeShape * edge,int32 index) const109 void b2ChainShape::GetChildEdge(b2EdgeShape* edge, int32 index) const
110 {
111 b2Assert(0 <= index && index < m_count - 1);
112 edge->m_type = b2Shape::e_edge;
113 edge->m_radius = m_radius;
114
115 edge->m_vertex1 = m_vertices[index + 0];
116 edge->m_vertex2 = m_vertices[index + 1];
117
118 if (index > 0)
119 {
120 edge->m_vertex0 = m_vertices[index - 1];
121 edge->m_hasVertex0 = true;
122 }
123 else
124 {
125 edge->m_vertex0 = m_prevVertex;
126 edge->m_hasVertex0 = m_hasPrevVertex;
127 }
128
129 if (index < m_count - 2)
130 {
131 edge->m_vertex3 = m_vertices[index + 2];
132 edge->m_hasVertex3 = true;
133 }
134 else
135 {
136 edge->m_vertex3 = m_nextVertex;
137 edge->m_hasVertex3 = m_hasNextVertex;
138 }
139 }
140
TestPoint(const b2Transform & xf,const b2Vec2 & p) const141 bool b2ChainShape::TestPoint(const b2Transform& xf, const b2Vec2& p) const
142 {
143 B2_NOT_USED(xf);
144 B2_NOT_USED(p);
145 return false;
146 }
147
RayCast(b2RayCastOutput * output,const b2RayCastInput & input,const b2Transform & xf,int32 childIndex) const148 bool b2ChainShape::RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
149 const b2Transform& xf, int32 childIndex) const
150 {
151 b2Assert(childIndex < m_count);
152
153 b2EdgeShape edgeShape;
154
155 int32 i1 = childIndex;
156 int32 i2 = childIndex + 1;
157 if (i2 == m_count)
158 {
159 i2 = 0;
160 }
161
162 edgeShape.m_vertex1 = m_vertices[i1];
163 edgeShape.m_vertex2 = m_vertices[i2];
164
165 return edgeShape.RayCast(output, input, xf, 0);
166 }
167
ComputeAABB(b2AABB * aabb,const b2Transform & xf,int32 childIndex) const168 void b2ChainShape::ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) const
169 {
170 b2Assert(childIndex < m_count);
171
172 int32 i1 = childIndex;
173 int32 i2 = childIndex + 1;
174 if (i2 == m_count)
175 {
176 i2 = 0;
177 }
178
179 b2Vec2 v1 = b2Mul(xf, m_vertices[i1]);
180 b2Vec2 v2 = b2Mul(xf, m_vertices[i2]);
181
182 aabb->lowerBound = b2Min(v1, v2);
183 aabb->upperBound = b2Max(v1, v2);
184 }
185
ComputeMass(b2MassData * massData,float32 density) const186 void b2ChainShape::ComputeMass(b2MassData* massData, float32 density) const
187 {
188 B2_NOT_USED(density);
189
190 massData->mass = 0.0f;
191 massData->center.SetZero();
192 massData->I = 0.0f;
193 }
194