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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/*
* 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.
*/
#ifndef CHARACTER_COLLISION_H
#define CHARACTER_COLLISION_H
/// This is a test of typical character collision scenarios. This does not
/// show how you should implement a character in your application.
/// Instead this is used to test smooth collision on edge chains.
class CharacterCollision : public Test
{
public:
CharacterCollision()
{
// Ground body
{
b2BodyDef bd;
b2Body* ground = m_world->CreateBody(&bd);
b2EdgeShape shape;
shape.Set(b2Vec2(-20.0f, 0.0f), b2Vec2(20.0f, 0.0f));
ground->CreateFixture(&shape, 0.0f);
}
// Collinear edges with no adjacency information.
// This shows the problematic case where a box shape can hit
// an internal vertex.
{
b2BodyDef bd;
b2Body* ground = m_world->CreateBody(&bd);
b2EdgeShape shape;
shape.Set(b2Vec2(-8.0f, 1.0f), b2Vec2(-6.0f, 1.0f));
ground->CreateFixture(&shape, 0.0f);
shape.Set(b2Vec2(-6.0f, 1.0f), b2Vec2(-4.0f, 1.0f));
ground->CreateFixture(&shape, 0.0f);
shape.Set(b2Vec2(-4.0f, 1.0f), b2Vec2(-2.0f, 1.0f));
ground->CreateFixture(&shape, 0.0f);
}
// Chain shape
{
b2BodyDef bd;
bd.angle = 0.25f * b2_pi;
b2Body* ground = m_world->CreateBody(&bd);
b2Vec2 vs[4];
vs[0].Set(5.0f, 7.0f);
vs[1].Set(6.0f, 8.0f);
vs[2].Set(7.0f, 8.0f);
vs[3].Set(8.0f, 7.0f);
b2ChainShape shape;
shape.CreateChain(vs, 4);
ground->CreateFixture(&shape, 0.0f);
}
// Square tiles. This shows that adjacency shapes may
// have non-smooth collision. There is no solution
// to this problem.
{
b2BodyDef bd;
b2Body* ground = m_world->CreateBody(&bd);
b2PolygonShape shape;
shape.SetAsBox(1.0f, 1.0f, b2Vec2(4.0f, 3.0f), 0.0f);
ground->CreateFixture(&shape, 0.0f);
shape.SetAsBox(1.0f, 1.0f, b2Vec2(6.0f, 3.0f), 0.0f);
ground->CreateFixture(&shape, 0.0f);
shape.SetAsBox(1.0f, 1.0f, b2Vec2(8.0f, 3.0f), 0.0f);
ground->CreateFixture(&shape, 0.0f);
}
// Square made from an edge loop. Collision should be smooth.
{
b2BodyDef bd;
b2Body* ground = m_world->CreateBody(&bd);
b2Vec2 vs[4];
vs[0].Set(-1.0f, 3.0f);
vs[1].Set(1.0f, 3.0f);
vs[2].Set(1.0f, 5.0f);
vs[3].Set(-1.0f, 5.0f);
b2ChainShape shape;
shape.CreateLoop(vs, 4);
ground->CreateFixture(&shape, 0.0f);
}
// Edge loop. Collision should be smooth.
{
b2BodyDef bd;
bd.position.Set(-10.0f, 4.0f);
b2Body* ground = m_world->CreateBody(&bd);
b2Vec2 vs[10];
vs[0].Set(0.0f, 0.0f);
vs[1].Set(6.0f, 0.0f);
vs[2].Set(6.0f, 2.0f);
vs[3].Set(4.0f, 1.0f);
vs[4].Set(2.0f, 2.0f);
vs[5].Set(0.0f, 2.0f);
vs[6].Set(-2.0f, 2.0f);
vs[7].Set(-4.0f, 3.0f);
vs[8].Set(-6.0f, 2.0f);
vs[9].Set(-6.0f, 0.0f);
b2ChainShape shape;
shape.CreateLoop(vs, 10);
ground->CreateFixture(&shape, 0.0f);
}
// Square character 1
{
b2BodyDef bd;
bd.position.Set(-3.0f, 8.0f);
bd.type = b2_dynamicBody;
bd.fixedRotation = true;
bd.allowSleep = false;
b2Body* body = m_world->CreateBody(&bd);
b2PolygonShape shape;
shape.SetAsBox(0.5f, 0.5f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
body->CreateFixture(&fd);
}
// Square character 2
{
b2BodyDef bd;
bd.position.Set(-5.0f, 5.0f);
bd.type = b2_dynamicBody;
bd.fixedRotation = true;
bd.allowSleep = false;
b2Body* body = m_world->CreateBody(&bd);
b2PolygonShape shape;
shape.SetAsBox(0.25f, 0.25f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
body->CreateFixture(&fd);
}
// Hexagon character
{
b2BodyDef bd;
bd.position.Set(-5.0f, 8.0f);
bd.type = b2_dynamicBody;
bd.fixedRotation = true;
bd.allowSleep = false;
b2Body* body = m_world->CreateBody(&bd);
float32 angle = 0.0f;
float32 delta = b2_pi / 3.0f;
b2Vec2 vertices[6];
for (int32 i = 0; i < 6; ++i)
{
vertices[i].Set(0.5f * cosf(angle), 0.5f * sinf(angle));
angle += delta;
}
b2PolygonShape shape;
shape.Set(vertices, 6);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
body->CreateFixture(&fd);
}
// Circle character
{
b2BodyDef bd;
bd.position.Set(3.0f, 5.0f);
bd.type = b2_dynamicBody;
bd.fixedRotation = true;
bd.allowSleep = false;
b2Body* body = m_world->CreateBody(&bd);
b2CircleShape shape;
shape.m_radius = 0.5f;
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
body->CreateFixture(&fd);
}
// Circle character
{
b2BodyDef bd;
bd.position.Set(-7.0f, 6.0f);
bd.type = b2_dynamicBody;
bd.allowSleep = false;
m_character = m_world->CreateBody(&bd);
b2CircleShape shape;
shape.m_radius = 0.25f;
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 20.0f;
fd.friction = 1.0f;
m_character->CreateFixture(&fd);
}
}
void Step(Settings* settings)
{
b2Vec2 v = m_character->GetLinearVelocity();
v.x = -5.0f;
m_character->SetLinearVelocity(v);
Test::Step(settings);
m_debugDraw.DrawString(5, m_textLine, "This tests various character collision shapes.");
m_textLine += 15;
m_debugDraw.DrawString(5, m_textLine, "Limitation: square and hexagon can snag on aligned boxes.");
m_textLine += 15;
m_debugDraw.DrawString(5, m_textLine, "Feature: edge chains have smooth collision inside and out.");
m_textLine += 15;
}
static Test* Create()
{
return new CharacterCollision;
}
b2Body* m_character;
};
#endif
|
