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
|
/*
* Copyright (c) 2006-2009 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 APPLY_FORCE_H
#define APPLY_FORCE_H
class ApplyForce : public Test
{
public:
ApplyForce()
{
m_world->SetGravity(b2Vec2(0.0f, 0.0f));
const float32 k_restitution = 0.4f;
b2Body* ground;
{
b2BodyDef bd;
bd.position.Set(0.0f, 20.0f);
ground = m_world->CreateBody(&bd);
b2EdgeShape shape;
b2FixtureDef sd;
sd.shape = &shape;
sd.density = 0.0f;
sd.restitution = k_restitution;
// Left vertical
shape.Set(b2Vec2(-20.0f, -20.0f), b2Vec2(-20.0f, 20.0f));
ground->CreateFixture(&sd);
// Right vertical
shape.Set(b2Vec2(20.0f, -20.0f), b2Vec2(20.0f, 20.0f));
ground->CreateFixture(&sd);
// Top horizontal
shape.Set(b2Vec2(-20.0f, 20.0f), b2Vec2(20.0f, 20.0f));
ground->CreateFixture(&sd);
// Bottom horizontal
shape.Set(b2Vec2(-20.0f, -20.0f), b2Vec2(20.0f, -20.0f));
ground->CreateFixture(&sd);
}
{
b2Transform xf1;
xf1.q.Set(0.3524f * b2_pi);
xf1.p = xf1.q.GetXAxis();
b2Vec2 vertices[3];
vertices[0] = b2Mul(xf1, b2Vec2(-1.0f, 0.0f));
vertices[1] = b2Mul(xf1, b2Vec2(1.0f, 0.0f));
vertices[2] = b2Mul(xf1, b2Vec2(0.0f, 0.5f));
b2PolygonShape poly1;
poly1.Set(vertices, 3);
b2FixtureDef sd1;
sd1.shape = &poly1;
sd1.density = 4.0f;
b2Transform xf2;
xf2.q.Set(-0.3524f * b2_pi);
xf2.p = -xf2.q.GetXAxis();
vertices[0] = b2Mul(xf2, b2Vec2(-1.0f, 0.0f));
vertices[1] = b2Mul(xf2, b2Vec2(1.0f, 0.0f));
vertices[2] = b2Mul(xf2, b2Vec2(0.0f, 0.5f));
b2PolygonShape poly2;
poly2.Set(vertices, 3);
b2FixtureDef sd2;
sd2.shape = &poly2;
sd2.density = 2.0f;
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.angularDamping = 5.0f;
bd.linearDamping = 0.1f;
bd.position.Set(0.0f, 2.0f);
bd.angle = b2_pi;
bd.allowSleep = false;
m_body = m_world->CreateBody(&bd);
m_body->CreateFixture(&sd1);
m_body->CreateFixture(&sd2);
}
{
b2PolygonShape shape;
shape.SetAsBox(0.5f, 0.5f);
b2FixtureDef fd;
fd.shape = &shape;
fd.density = 1.0f;
fd.friction = 0.3f;
for (int i = 0; i < 10; ++i)
{
b2BodyDef bd;
bd.type = b2_dynamicBody;
bd.position.Set(0.0f, 5.0f + 1.54f * i);
b2Body* body = m_world->CreateBody(&bd);
body->CreateFixture(&fd);
float32 gravity = 10.0f;
float32 I = body->GetInertia();
float32 mass = body->GetMass();
// For a circle: I = 0.5 * m * r * r ==> r = sqrt(2 * I / m)
float32 radius = b2Sqrt(2.0f * I / mass);
b2FrictionJointDef jd;
jd.localAnchorA.SetZero();
jd.localAnchorB.SetZero();
jd.bodyA = ground;
jd.bodyB = body;
jd.collideConnected = true;
jd.maxForce = mass * gravity;
jd.maxTorque = mass * radius * gravity;
m_world->CreateJoint(&jd);
}
}
}
void Keyboard(unsigned char key)
{
switch (key)
{
case 'w':
{
b2Vec2 f = m_body->GetWorldVector(b2Vec2(0.0f, -200.0f));
b2Vec2 p = m_body->GetWorldPoint(b2Vec2(0.0f, 2.0f));
m_body->ApplyForce(f, p);
}
break;
case 'a':
{
m_body->ApplyTorque(50.0f);
}
break;
case 'd':
{
m_body->ApplyTorque(-50.0f);
}
break;
}
}
static Test* Create()
{
return new ApplyForce;
}
b2Body* m_body;
};
#endif
|
