JUCE/examples/Demo/Source/Demos/Box2DTests/Cantilever.h

/*
* 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