axmol/samples/TestCpp/Classes/Box2DTestBed/Tests/Gears.h

/*
* Copyright (c) 2007-2009 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 GEARS_H
#define GEARS_H

class Gears : public Test
{
public:
    Gears()
    {
        b2Body* ground = NULL;
        {
            b2BodyDef bd;
            ground = m_world->CreateBody(&bd);

            b2EdgeShape shape;
            shape.Set(b2Vec2(50.0f, 0.0f), b2Vec2(-50.0f, 0.0f));
            ground->CreateFixture(&shape, 0.0f);
        }

        // Gears co
        {
            b2CircleShape circle1;
            circle1.m_radius = 1.0f;

            b2PolygonShape box;
            box.SetAsBox(0.5f, 5.0f);

            b2CircleShape circle2;
            circle2.m_radius = 2.0f;
            
            b2BodyDef bd1;
            bd1.type = b2_staticBody;
            bd1.position.Set(10.0f, 9.0f);
            b2Body* body1 = m_world->CreateBody(&bd1);
            body1->CreateFixture(&circle1, 0.0f);

            b2BodyDef bd2;
            bd2.type = b2_dynamicBody;
            bd2.position.Set(10.0f, 8.0f);
            b2Body* body2 = m_world->CreateBody(&bd2);
            body2->CreateFixture(&box, 5.0f);

            b2BodyDef bd3;
            bd3.type = b2_dynamicBody;
            bd3.position.Set(10.0f, 6.0f);
            b2Body* body3 = m_world->CreateBody(&bd3);
            body3->CreateFixture(&circle2, 5.0f);

            b2RevoluteJointDef jd1;
            jd1.Initialize(body2, body1, bd1.position);
            b2Joint* joint1 = m_world->CreateJoint(&jd1);

            b2RevoluteJointDef jd2;
            jd2.Initialize(body2, body3, bd3.position);
            b2Joint* joint2 = m_world->CreateJoint(&jd2);

            b2GearJointDef jd4;
            jd4.bodyA = body1;
            jd4.bodyB = body3;
            jd4.joint1 = joint1;
            jd4.joint2 = joint2;
            jd4.ratio = circle2.m_radius / circle1.m_radius;
            m_world->CreateJoint(&jd4);
        }

        {
            b2CircleShape circle1;
            circle1.m_radius = 1.0f;

            b2CircleShape circle2;
            circle2.m_radius = 2.0f;
            
            b2PolygonShape box;
            box.SetAsBox(0.5f, 5.0f);

            b2BodyDef bd1;
            bd1.type = b2_dynamicBody;
            bd1.position.Set(-3.0f, 12.0f);
            b2Body* body1 = m_world->CreateBody(&bd1);
            body1->CreateFixture(&circle1, 5.0f);

            b2RevoluteJointDef jd1;
            jd1.bodyA = ground;
            jd1.bodyB = body1;
            jd1.localAnchorA = ground->GetLocalPoint(bd1.position);
            jd1.localAnchorB = body1->GetLocalPoint(bd1.position);
            jd1.referenceAngle = body1->GetAngle() - ground->GetAngle();
            m_joint1 = (b2RevoluteJoint*)m_world->CreateJoint(&jd1);

            b2BodyDef bd2;
            bd2.type = b2_dynamicBody;
            bd2.position.Set(0.0f, 12.0f);
            b2Body* body2 = m_world->CreateBody(&bd2);
            body2->CreateFixture(&circle2, 5.0f);

            b2RevoluteJointDef jd2;
            jd2.Initialize(ground, body2, bd2.position);
            m_joint2 = (b2RevoluteJoint*)m_world->CreateJoint(&jd2);

            b2BodyDef bd3;
            bd3.type = b2_dynamicBody;
            bd3.position.Set(2.5f, 12.0f);
            b2Body* body3 = m_world->CreateBody(&bd3);
            body3->CreateFixture(&box, 5.0f);

            b2PrismaticJointDef jd3;
            jd3.Initialize(ground, body3, bd3.position, b2Vec2(0.0f, 1.0f));
            jd3.lowerTranslation = -5.0f;
            jd3.upperTranslation = 5.0f;
            jd3.enableLimit = true;

            m_joint3 = (b2PrismaticJoint*)m_world->CreateJoint(&jd3);

            b2GearJointDef jd4;
            jd4.bodyA = body1;
            jd4.bodyB = body2;
            jd4.joint1 = m_joint1;
            jd4.joint2 = m_joint2;
            jd4.ratio = circle2.m_radius / circle1.m_radius;
            m_joint4 = (b2GearJoint*)m_world->CreateJoint(&jd4);

            b2GearJointDef jd5;
            jd5.bodyA = body2;
            jd5.bodyB = body3;
            jd5.joint1 = m_joint2;
            jd5.joint2 = m_joint3;
            jd5.ratio = -1.0f / circle2.m_radius;
            m_joint5 = (b2GearJoint*)m_world->CreateJoint(&jd5);
        }
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case 0:
            break;
        }
    }

    void Step(Settings* settings)
    {
        Test::Step(settings);

        float32 ratio, value;
        
        ratio = m_joint4->GetRatio();
        value = m_joint1->GetJointAngle() + ratio * m_joint2->GetJointAngle();
        m_debugDraw.DrawString(5, m_textLine, "theta1 + %4.2f * theta2 = %4.2f", (float) ratio, (float) value);
        m_textLine += 15;

        ratio = m_joint5->GetRatio();
        value = m_joint2->GetJointAngle() + ratio * m_joint3->GetJointTranslation();
        m_debugDraw.DrawString(5, m_textLine, "theta2 + %4.2f * delta = %4.2f", (float) ratio, (float) value);
        m_textLine += 15;
    }

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

    b2RevoluteJoint* m_joint1;
    b2RevoluteJoint* m_joint2;
    b2PrismaticJoint* m_joint3;
    b2GearJoint* m_joint4;
    b2GearJoint* m_joint5;
};

#endif