1 /* 2 * Copyright (c) 2006-2009 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 #ifndef APPLY_FORCE_H 20 #define APPLY_FORCE_H 21 22 class ApplyForce : public Test 23 { 24 public: ApplyForce()25 ApplyForce() 26 { 27 m_world->SetGravity(b2Vec2(0.0f, 0.0f)); 28 29 const float32 k_restitution = 0.4f; 30 31 b2Body* ground; 32 { 33 b2BodyDef bd; 34 bd.position.Set(0.0f, 20.0f); 35 ground = m_world->CreateBody(&bd); 36 37 b2EdgeShape shape; 38 39 b2FixtureDef sd; 40 sd.shape = &shape; 41 sd.density = 0.0f; 42 sd.restitution = k_restitution; 43 44 // Left vertical 45 shape.Set(b2Vec2(-20.0f, -20.0f), b2Vec2(-20.0f, 20.0f)); 46 ground->CreateFixture(&sd); 47 48 // Right vertical 49 shape.Set(b2Vec2(20.0f, -20.0f), b2Vec2(20.0f, 20.0f)); 50 ground->CreateFixture(&sd); 51 52 // Top horizontal 53 shape.Set(b2Vec2(-20.0f, 20.0f), b2Vec2(20.0f, 20.0f)); 54 ground->CreateFixture(&sd); 55 56 // Bottom horizontal 57 shape.Set(b2Vec2(-20.0f, -20.0f), b2Vec2(20.0f, -20.0f)); 58 ground->CreateFixture(&sd); 59 } 60 61 { 62 b2Transform xf1; 63 xf1.q.Set(0.3524f * b2_pi); 64 xf1.p = xf1.q.GetXAxis(); 65 66 b2Vec2 vertices[3]; 67 vertices[0] = b2Mul(xf1, b2Vec2(-1.0f, 0.0f)); 68 vertices[1] = b2Mul(xf1, b2Vec2(1.0f, 0.0f)); 69 vertices[2] = b2Mul(xf1, b2Vec2(0.0f, 0.5f)); 70 71 b2PolygonShape poly1; 72 poly1.Set(vertices, 3); 73 74 b2FixtureDef sd1; 75 sd1.shape = &poly1; 76 sd1.density = 4.0f; 77 78 b2Transform xf2; 79 xf2.q.Set(-0.3524f * b2_pi); 80 xf2.p = -xf2.q.GetXAxis(); 81 82 vertices[0] = b2Mul(xf2, b2Vec2(-1.0f, 0.0f)); 83 vertices[1] = b2Mul(xf2, b2Vec2(1.0f, 0.0f)); 84 vertices[2] = b2Mul(xf2, b2Vec2(0.0f, 0.5f)); 85 86 b2PolygonShape poly2; 87 poly2.Set(vertices, 3); 88 89 b2FixtureDef sd2; 90 sd2.shape = &poly2; 91 sd2.density = 2.0f; 92 93 b2BodyDef bd; 94 bd.type = b2_dynamicBody; 95 bd.angularDamping = 5.0f; 96 bd.linearDamping = 0.1f; 97 98 bd.position.Set(0.0f, 2.0f); 99 bd.angle = b2_pi; 100 bd.allowSleep = false; 101 m_body = m_world->CreateBody(&bd); 102 m_body->CreateFixture(&sd1); 103 m_body->CreateFixture(&sd2); 104 } 105 106 { 107 b2PolygonShape shape; 108 shape.SetAsBox(0.5f, 0.5f); 109 110 b2FixtureDef fd; 111 fd.shape = &shape; 112 fd.density = 1.0f; 113 fd.friction = 0.3f; 114 115 for (int i = 0; i < 10; ++i) 116 { 117 b2BodyDef bd; 118 bd.type = b2_dynamicBody; 119 120 bd.position.Set(0.0f, 5.0f + 1.54f * i); 121 b2Body* body = m_world->CreateBody(&bd); 122 123 body->CreateFixture(&fd); 124 125 float32 gravity = 10.0f; 126 float32 I = body->GetInertia(); 127 float32 mass = body->GetMass(); 128 129 // For a circle: I = 0.5 * m * r * r ==> r = sqrt(2 * I / m) 130 float32 radius = b2Sqrt(2.0f * I / mass); 131 132 b2FrictionJointDef jd; 133 jd.localAnchorA.SetZero(); 134 jd.localAnchorB.SetZero(); 135 jd.bodyA = ground; 136 jd.bodyB = body; 137 jd.collideConnected = true; 138 jd.maxForce = mass * gravity; 139 jd.maxTorque = mass * radius * gravity; 140 141 m_world->CreateJoint(&jd); 142 } 143 } 144 } 145 Keyboard(unsigned char key)146 void Keyboard(unsigned char key) 147 { 148 switch (key) 149 { 150 case 'w': 151 { 152 b2Vec2 f = m_body->GetWorldVector(b2Vec2(0.0f, -200.0f)); 153 b2Vec2 p = m_body->GetWorldPoint(b2Vec2(0.0f, 2.0f)); 154 m_body->ApplyForce(f, p); 155 } 156 break; 157 158 case 'a': 159 { 160 m_body->ApplyTorque(50.0f); 161 } 162 break; 163 164 case 'd': 165 { 166 m_body->ApplyTorque(-50.0f); 167 } 168 break; 169 170 default: 171 break; 172 } 173 } 174 Create()175 static Test* Create() 176 { 177 return new ApplyForce; 178 } 179 180 b2Body* m_body; 181 }; 182 183 #endif 184