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

/*
* 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 SLIDER_CRANK_H
#define SLIDER_CRANK_H

// A motor driven slider crank with joint friction.

class SliderCrank : public Test
{
public:
    SliderCrank()
    {
        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);
        }

        {
            b2Body* prevBody = ground;

            // Define crank.
            {
                b2PolygonShape shape;
                shape.SetAsBox(0.5f, 2.0f);

                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(0.0f, 7.0f);
                b2Body* body = m_world->CreateBody(&bd);
                body->CreateFixture(&shape, 2.0f);

                b2RevoluteJointDef rjd;
                rjd.Initialize(prevBody, body, b2Vec2(0.0f, 5.0f));
                rjd.motorSpeed = 1.0f * b2_pi;
                rjd.maxMotorTorque = 10000.0f;
                rjd.enableMotor = true;
                m_joint1 = (b2RevoluteJoint*)m_world->CreateJoint(&rjd);

                prevBody = body;
            }

            // Define follower.
            {
                b2PolygonShape shape;
                shape.SetAsBox(0.5f, 4.0f);

                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(0.0f, 13.0f);
                b2Body* body = m_world->CreateBody(&bd);
                body->CreateFixture(&shape, 2.0f);

                b2RevoluteJointDef rjd;
                rjd.Initialize(prevBody, body, b2Vec2(0.0f, 9.0f));
                rjd.enableMotor = false;
                m_world->CreateJoint(&rjd);

                prevBody = body;
            }

            // Define piston
            {
                b2PolygonShape shape;
                shape.SetAsBox(1.5f, 1.5f);

                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.fixedRotation = true;
                bd.position.Set(0.0f, 17.0f);
                b2Body* body = m_world->CreateBody(&bd);
                body->CreateFixture(&shape, 2.0f);

                b2RevoluteJointDef rjd;
                rjd.Initialize(prevBody, body, b2Vec2(0.0f, 17.0f));
                m_world->CreateJoint(&rjd);

                b2PrismaticJointDef pjd;
                pjd.Initialize(ground, body, b2Vec2(0.0f, 17.0f), b2Vec2(0.0f, 1.0f));

                pjd.maxMotorForce = 1000.0f;
                pjd.enableMotor = true;

                m_joint2 = (b2PrismaticJoint*)m_world->CreateJoint(&pjd);
            }

            // Create a payload
            {
                b2PolygonShape shape;
                shape.SetAsBox(1.5f, 1.5f);

                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(0.0f, 23.0f);
                b2Body* body = m_world->CreateBody(&bd);
                body->CreateFixture(&shape, 2.0f);
            }
        }
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case 'f':
            m_joint2->EnableMotor(!m_joint2->IsMotorEnabled());
            m_joint2->GetBodyB()->SetAwake(true);
            break;

        case 'm':
            m_joint1->EnableMotor(!m_joint1->IsMotorEnabled());
            m_joint1->GetBodyB()->SetAwake(true);
            break;
        }
    }

    void Step(Settings* settings)
    {
        Test::Step(settings);
        m_debugDraw.DrawString(5, m_textLine, "Keys: (f) toggle friction, (m) toggle motor");
        m_textLine += 15;
        float32 torque = m_joint1->GetMotorTorque(settings->hz);
        m_debugDraw.DrawString(5, m_textLine, "Motor Torque = %5.0f", (float) torque);
        m_textLine += 15;
    }

    static Test* Create()
    {
        return new SliderCrank;
    }

    b2RevoluteJoint* m_joint1;
    b2PrismaticJoint* m_joint2;
};

#endif