JUCE/examples/Demo/Source/Demos/Box2DTests/Car.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 CAR_H
#define CAR_H

// This is a fun demo that shows off the wheel joint
class Car : public Test
{
public:
    Car()
    {
        m_hz = 4.0f;
        m_zeta = 0.7f;
        m_speed = 50.0f;

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

            b2EdgeShape shape;

            b2FixtureDef fd;
            fd.shape = &shape;
            fd.density = 0.0f;
            fd.friction = 0.6f;

            shape.Set(b2Vec2(-20.0f, 0.0f), b2Vec2(20.0f, 0.0f));
            ground->CreateFixture(&fd);

            float32 hs[10] = {0.25f, 1.0f, 4.0f, 0.0f, 0.0f, -1.0f, -2.0f, -2.0f, -1.25f, 0.0f};

            float32 x = 20.0f, y1 = 0.0f, dx = 5.0f;

            for (int32 i = 0; i < 10; ++i)
            {
                float32 y2 = hs[i];
                shape.Set(b2Vec2(x, y1), b2Vec2(x + dx, y2));
                ground->CreateFixture(&fd);
                y1 = y2;
                x += dx;
            }

            for (int32 i = 0; i < 10; ++i)
            {
                float32 y2 = hs[i];
                shape.Set(b2Vec2(x, y1), b2Vec2(x + dx, y2));
                ground->CreateFixture(&fd);
                y1 = y2;
                x += dx;
            }

            shape.Set(b2Vec2(x, 0.0f), b2Vec2(x + 40.0f, 0.0f));
            ground->CreateFixture(&fd);

            x += 80.0f;
            shape.Set(b2Vec2(x, 0.0f), b2Vec2(x + 40.0f, 0.0f));
            ground->CreateFixture(&fd);

            x += 40.0f;
            shape.Set(b2Vec2(x, 0.0f), b2Vec2(x + 10.0f, 5.0f));
            ground->CreateFixture(&fd);

            x += 20.0f;
            shape.Set(b2Vec2(x, 0.0f), b2Vec2(x + 40.0f, 0.0f));
            ground->CreateFixture(&fd);

            x += 40.0f;
            shape.Set(b2Vec2(x, 0.0f), b2Vec2(x, 20.0f));
            ground->CreateFixture(&fd);
        }

        // Teeter
        {
            b2BodyDef bd;
            bd.position.Set(140.0f, 1.0f);
            bd.type = b2_dynamicBody;
            b2Body* body = m_world->CreateBody(&bd);

            b2PolygonShape box;
            box.SetAsBox(10.0f, 0.25f);
            body->CreateFixture(&box, 1.0f);

            b2RevoluteJointDef jd;
            jd.Initialize(ground, body, body->GetPosition());
            jd.lowerAngle = -8.0f * b2_pi / 180.0f;
            jd.upperAngle = 8.0f * b2_pi / 180.0f;
            jd.enableLimit = true;
            m_world->CreateJoint(&jd);

            body->ApplyAngularImpulse(100.0f);
        }

        // Bridge
        {
            int32 N = 20;
            b2PolygonShape shape;
            shape.SetAsBox(1.0f, 0.125f);

            b2FixtureDef fd;
            fd.shape = &shape;
            fd.density = 1.0f;
            fd.friction = 0.6f;

            b2RevoluteJointDef jd;

            b2Body* prevBody = ground;
            for (int32 i = 0; i < N; ++i)
            {
                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(161.0f + 2.0f * i, -0.125f);
                b2Body* body = m_world->CreateBody(&bd);
                body->CreateFixture(&fd);

                b2Vec2 anchor(160.0f + 2.0f * i, -0.125f);
                jd.Initialize(prevBody, body, anchor);
                m_world->CreateJoint(&jd);

                prevBody = body;
            }

            b2Vec2 anchor(160.0f + 2.0f * N, -0.125f);
            jd.Initialize(prevBody, ground, anchor);
            m_world->CreateJoint(&jd);
        }

        // Boxes
        {
            b2PolygonShape box;
            box.SetAsBox(0.5f, 0.5f);

            b2Body* body = NULL;
            b2BodyDef bd;
            bd.type = b2_dynamicBody;

            bd.position.Set(230.0f, 0.5f);
            body = m_world->CreateBody(&bd);
            body->CreateFixture(&box, 0.5f);

            bd.position.Set(230.0f, 1.5f);
            body = m_world->CreateBody(&bd);
            body->CreateFixture(&box, 0.5f);

            bd.position.Set(230.0f, 2.5f);
            body = m_world->CreateBody(&bd);
            body->CreateFixture(&box, 0.5f);

            bd.position.Set(230.0f, 3.5f);
            body = m_world->CreateBody(&bd);
            body->CreateFixture(&box, 0.5f);

            bd.position.Set(230.0f, 4.5f);
            body = m_world->CreateBody(&bd);
            body->CreateFixture(&box, 0.5f);
        }

        // Car
        {
            b2PolygonShape chassis;
            b2Vec2 vertices[8];
            vertices[0].Set(-1.5f, -0.5f);
            vertices[1].Set(1.5f, -0.5f);
            vertices[2].Set(1.5f, 0.0f);
            vertices[3].Set(0.0f, 0.9f);
            vertices[4].Set(-1.15f, 0.9f);
            vertices[5].Set(-1.5f, 0.2f);
            chassis.Set(vertices, 6);

            b2CircleShape circle;
            circle.m_radius = 0.4f;

            b2BodyDef bd;
            bd.type = b2_dynamicBody;
            bd.position.Set(0.0f, 1.0f);
            m_car = m_world->CreateBody(&bd);
            m_car->CreateFixture(&chassis, 1.0f);

            b2FixtureDef fd;
            fd.shape = &circle;
            fd.density = 1.0f;
            fd.friction = 0.9f;

            bd.position.Set(-1.0f, 0.35f);
            m_wheel1 = m_world->CreateBody(&bd);
            m_wheel1->CreateFixture(&fd);

            bd.position.Set(1.0f, 0.4f);
            m_wheel2 = m_world->CreateBody(&bd);
            m_wheel2->CreateFixture(&fd);

            b2WheelJointDef jd;
            b2Vec2 axis(0.0f, 1.0f);

            jd.Initialize(m_car, m_wheel1, m_wheel1->GetPosition(), axis);
            jd.motorSpeed = 0.0f;
            jd.maxMotorTorque = 20.0f;
            jd.enableMotor = true;
            jd.frequencyHz = m_hz;
            jd.dampingRatio = m_zeta;
            m_spring1 = (b2WheelJoint*)m_world->CreateJoint(&jd);

            jd.Initialize(m_car, m_wheel2, m_wheel2->GetPosition(), axis);
            jd.motorSpeed = 0.0f;
            jd.maxMotorTorque = 10.0f;
            jd.enableMotor = false;
            jd.frequencyHz = m_hz;
            jd.dampingRatio = m_zeta;
            m_spring2 = (b2WheelJoint*)m_world->CreateJoint(&jd);
        }
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case 'a':
            m_spring1->SetMotorSpeed(m_speed);
            break;

        case 's':
            m_spring1->SetMotorSpeed(0.0f);
            break;

        case 'd':
            m_spring1->SetMotorSpeed(-m_speed);
            break;

        case 'q':
            m_hz = b2Max(0.0f, m_hz - 1.0f);
            m_spring1->SetSpringFrequencyHz(m_hz);
            m_spring2->SetSpringFrequencyHz(m_hz);
            break;

        case 'e':
            m_hz += 1.0f;
            m_spring1->SetSpringFrequencyHz(m_hz);
            m_spring2->SetSpringFrequencyHz(m_hz);
            break;
        }
    }

    void Step(Settings* settings)
    {
        m_debugDraw.DrawString(5, m_textLine, "Keys: left = a, brake = s, right = d, hz down = q, hz up = e");
        m_textLine += 15;
        m_debugDraw.DrawString(5, m_textLine, "frequency = %g hz, damping ratio = %g", m_hz, m_zeta);
        m_textLine += 15;

        settings->viewCenter.x = m_car->GetPosition().x;
        Test::Step(settings);
    }

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

    b2Body* m_car;
    b2Body* m_wheel1;
    b2Body* m_wheel2;

    float32 m_hz;
    float32 m_zeta;
    float32 m_speed;
    b2WheelJoint* m_spring1;
    b2WheelJoint* m_spring2;
};

#endif