JUCE/examples/Assets/Box2DTests/TheoJansen.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.
*/

// Inspired by a contribution by roman_m
// Dimensions scooped from APE (http://www.cove.org/ape/index.htm)

#ifndef THEO_JANSEN_H
#define THEO_JANSEN_H

class TheoJansen : public Test
{
public:

    void CreateLeg(float32 s, const b2Vec2& wheelAnchor)
    {
        b2Vec2 p1(5.4f * s, -6.1f);
        b2Vec2 p2(7.2f * s, -1.2f);
        b2Vec2 p3(4.3f * s, -1.9f);
        b2Vec2 p4(3.1f * s, 0.8f);
        b2Vec2 p5(6.0f * s, 1.5f);
        b2Vec2 p6(2.5f * s, 3.7f);

        b2FixtureDef fd1, fd2;
        fd1.filter.groupIndex = -1;
        fd2.filter.groupIndex = -1;
        fd1.density = 1.0f;
        fd2.density = 1.0f;

        b2PolygonShape poly1, poly2;

        if (s > 0.0f)
        {
            b2Vec2 vertices[3];

            vertices[0] = p1;
            vertices[1] = p2;
            vertices[2] = p3;
            poly1.Set(vertices, 3);

            vertices[0] = b2Vec2_zero;
            vertices[1] = p5 - p4;
            vertices[2] = p6 - p4;
            poly2.Set(vertices, 3);
        }
        else
        {
            b2Vec2 vertices[3];

            vertices[0] = p1;
            vertices[1] = p3;
            vertices[2] = p2;
            poly1.Set(vertices, 3);

            vertices[0] = b2Vec2_zero;
            vertices[1] = p6 - p4;
            vertices[2] = p5 - p4;
            poly2.Set(vertices, 3);
        }

        fd1.shape = &poly1;
        fd2.shape = &poly2;

        b2BodyDef bd1, bd2;
        bd1.type = b2_dynamicBody;
        bd2.type = b2_dynamicBody;
        bd1.position = m_offset;
        bd2.position = p4 + m_offset;

        bd1.angularDamping = 10.0f;
        bd2.angularDamping = 10.0f;

        b2Body* body1 = m_world->CreateBody(&bd1);
        b2Body* body2 = m_world->CreateBody(&bd2);

        body1->CreateFixture(&fd1);
        body2->CreateFixture(&fd2);

        b2DistanceJointDef djd;

        // Using a soft distance constraint can reduce some jitter.
        // It also makes the structure seem a bit more fluid by
        // acting like a suspension system.
        djd.dampingRatio = 0.5f;
        djd.frequencyHz = 10.0f;

        djd.Initialize(body1, body2, p2 + m_offset, p5 + m_offset);
        m_world->CreateJoint(&djd);

        djd.Initialize(body1, body2, p3 + m_offset, p4 + m_offset);
        m_world->CreateJoint(&djd);

        djd.Initialize(body1, m_wheel, p3 + m_offset, wheelAnchor + m_offset);
        m_world->CreateJoint(&djd);

        djd.Initialize(body2, m_wheel, p6 + m_offset, wheelAnchor + m_offset);
        m_world->CreateJoint(&djd);

        b2RevoluteJointDef rjd;

        rjd.Initialize(body2, m_chassis, p4 + m_offset);
        m_world->CreateJoint(&rjd);
    }

    TheoJansen()
    {
        m_offset.Set(0.0f, 8.0f);
        m_motorSpeed = 2.0f;
        m_motorOn = true;
        b2Vec2 pivot(0.0f, 0.8f);

        // Ground
        {
            b2BodyDef bd;
            b2Body* ground = m_world->CreateBody(&bd);

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

            shape.Set(b2Vec2(-50.0f, 0.0f), b2Vec2(-50.0f, 10.0f));
            ground->CreateFixture(&shape, 0.0f);

            shape.Set(b2Vec2(50.0f, 0.0f), b2Vec2(50.0f, 10.0f));
            ground->CreateFixture(&shape, 0.0f);
        }

        // Balls
        for (int32 i = 0; i < 40; ++i)
        {
            b2CircleShape shape;
            shape.m_radius = 0.25f;

            b2BodyDef bd;
            bd.type = b2_dynamicBody;
            bd.position.Set(-40.0f + 2.0f * i, 0.5f);

            b2Body* body = m_world->CreateBody(&bd);
            body->CreateFixture(&shape, 1.0f);
        }

        // Chassis
        {
            b2PolygonShape shape;
            shape.SetAsBox(2.5f, 1.0f);

            b2FixtureDef sd;
            sd.density = 1.0f;
            sd.shape = &shape;
            sd.filter.groupIndex = -1;
            b2BodyDef bd;
            bd.type = b2_dynamicBody;
            bd.position = pivot + m_offset;
            m_chassis = m_world->CreateBody(&bd);
            m_chassis->CreateFixture(&sd);
        }

        {
            b2CircleShape shape;
            shape.m_radius = 1.6f;

            b2FixtureDef sd;
            sd.density = 1.0f;
            sd.shape = &shape;
            sd.filter.groupIndex = -1;
            b2BodyDef bd;
            bd.type = b2_dynamicBody;
            bd.position = pivot + m_offset;
            m_wheel = m_world->CreateBody(&bd);
            m_wheel->CreateFixture(&sd);
        }

        {
            b2RevoluteJointDef jd;
            jd.Initialize(m_wheel, m_chassis, pivot + m_offset);
            jd.collideConnected = false;
            jd.motorSpeed = m_motorSpeed;
            jd.maxMotorTorque = 400.0f;
            jd.enableMotor = m_motorOn;
            m_motorJoint = (b2RevoluteJoint*)m_world->CreateJoint(&jd);
        }

        b2Vec2 wheelAnchor;

        wheelAnchor = pivot + b2Vec2(0.0f, -0.8f);

        CreateLeg(-1.0f, wheelAnchor);
        CreateLeg(1.0f, wheelAnchor);

        m_wheel->SetTransform(m_wheel->GetPosition(), 120.0f * b2_pi / 180.0f);
        CreateLeg(-1.0f, wheelAnchor);
        CreateLeg(1.0f, wheelAnchor);

        m_wheel->SetTransform(m_wheel->GetPosition(), -120.0f * b2_pi / 180.0f);
        CreateLeg(-1.0f, wheelAnchor);
        CreateLeg(1.0f, wheelAnchor);
    }

    void Step(Settings* settings)
    {
        m_debugDraw.DrawString(5, m_textLine, "Keys: left = a, brake = s, right = d, toggle motor = m");
        m_textLine += 15;

        Test::Step(settings);
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case 'a':
            m_motorJoint->SetMotorSpeed(-m_motorSpeed);
            break;

        case 's':
            m_motorJoint->SetMotorSpeed(0.0f);
            break;

        case 'd':
            m_motorJoint->SetMotorSpeed(m_motorSpeed);
            break;

        case 'm':
            m_motorJoint->EnableMotor(!m_motorJoint->IsMotorEnabled());
            break;
        }
    }

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

    b2Vec2 m_offset;
    b2Body* m_chassis;
    b2Body* m_wheel;
    b2RevoluteJoint* m_motorJoint;
    bool m_motorOn;
    float32 m_motorSpeed;
};

#endif // THEO_JANSEN_H