/* * Copyright (c) 2006-2011 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 CANTILEVER_H #define CANTILEVER_H // It is difficult to make a cantilever made of links completely rigid with weld joints. // You will have to use a high number of iterations to make them stiff. // So why not go ahead and use soft weld joints? They behave like a revolute // joint with a rotational spring. class Cantilever : public Test { public: enum { e_count = 8 }; Cantilever() { b2Body* ground = NULL; { b2BodyDef bd; ground = m_world->CreateBody(&bd); b2EdgeShape shape; shape.Set(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f)); ground->CreateFixture(&shape, 0.0f); } { b2PolygonShape shape; shape.SetAsBox(0.5f, 0.125f); b2FixtureDef fd; fd.shape = &shape; fd.density = 20.0f; b2WeldJointDef jd; b2Body* prevBody = ground; for (int32 i = 0; i < e_count; ++i) { b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-14.5f + 1.0f * i, 5.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); b2Vec2 anchor(-15.0f + 1.0f * i, 5.0f); jd.Initialize(prevBody, body, anchor); m_world->CreateJoint(&jd); prevBody = body; } } { b2PolygonShape shape; shape.SetAsBox(1.0f, 0.125f); b2FixtureDef fd; fd.shape = &shape; fd.density = 20.0f; b2WeldJointDef jd; jd.frequencyHz = 5.0f; jd.dampingRatio = 0.7f; b2Body* prevBody = ground; for (int32 i = 0; i < 3; ++i) { b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-14.0f + 2.0f * i, 15.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); b2Vec2 anchor(-15.0f + 2.0f * i, 15.0f); jd.Initialize(prevBody, body, anchor); m_world->CreateJoint(&jd); prevBody = body; } } { b2PolygonShape shape; shape.SetAsBox(0.5f, 0.125f); b2FixtureDef fd; fd.shape = &shape; fd.density = 20.0f; b2WeldJointDef jd; b2Body* prevBody = ground; for (int32 i = 0; i < e_count; ++i) { b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-4.5f + 1.0f * i, 5.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); if (i > 0) { b2Vec2 anchor(-5.0f + 1.0f * i, 5.0f); jd.Initialize(prevBody, body, anchor); m_world->CreateJoint(&jd); } prevBody = body; } } { b2PolygonShape shape; shape.SetAsBox(0.5f, 0.125f); b2FixtureDef fd; fd.shape = &shape; fd.density = 20.0f; b2WeldJointDef jd; jd.frequencyHz = 8.0f; jd.dampingRatio = 0.7f; b2Body* prevBody = ground; for (int32 i = 0; i < e_count; ++i) { b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(5.5f + 1.0f * i, 10.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); if (i > 0) { b2Vec2 anchor(5.0f + 1.0f * i, 10.0f); jd.Initialize(prevBody, body, anchor); m_world->CreateJoint(&jd); } prevBody = body; } } for (int32 i = 0; i < 2; ++i) { b2Vec2 vertices[3]; vertices[0].Set(-0.5f, 0.0f); vertices[1].Set(0.5f, 0.0f); vertices[2].Set(0.0f, 1.5f); b2PolygonShape shape; shape.Set(vertices, 3); b2FixtureDef fd; fd.shape = &shape; fd.density = 1.0f; b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-8.0f + 8.0f * i, 12.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); } for (int32 i = 0; i < 2; ++i) { b2CircleShape shape; shape.m_radius = 0.5f; b2FixtureDef fd; fd.shape = &shape; fd.density = 1.0f; b2BodyDef bd; bd.type = b2_dynamicBody; bd.position.Set(-6.0f + 6.0f * i, 10.0f); b2Body* body = m_world->CreateBody(&bd); body->CreateFixture(&fd); } } static Test* Create() { return new Cantilever; } b2Body* m_middle; }; #endif