JUCE/examples/Assets/Box2DTests/SensorTest.h

/*
* Copyright (c) 2008-2009 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 SENSOR_TEST_H
#define SENSOR_TEST_H

// This is used to test sensor shapes.
class SensorTest : public Test
{
public:

    enum
    {
        e_count = 7
    };

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

            {
                b2EdgeShape shape;
                shape.Set(b2Vec2(-40.0f, 0.0f), b2Vec2(40.0f, 0.0f));
                ground->CreateFixture(&shape, 0.0f);
            }

#if 0
            {
                b2FixtureDef sd;
                sd.SetAsBox(10.0f, 2.0f, b2Vec2(0.0f, 20.0f), 0.0f);
                sd.isSensor = true;
                m_sensor = ground->CreateFixture(&sd);
            }
#else
            {
                b2CircleShape shape;
                shape.m_radius = 5.0f;
                shape.m_p.Set(0.0f, 10.0f);

                b2FixtureDef fd;
                fd.shape = &shape;
                fd.isSensor = true;
                m_sensor = ground->CreateFixture(&fd);
            }
#endif
        }

        {
            b2CircleShape shape;
            shape.m_radius = 1.0f;

            for (int32 i = 0; i < e_count; ++i)
            {
                b2BodyDef bd;
                bd.type = b2_dynamicBody;
                bd.position.Set(-10.0f + 3.0f * i, 20.0f);
                bd.userData = m_touching + i;

                m_touching[i] = false;
                m_bodies[i] = m_world->CreateBody(&bd);

                m_bodies[i]->CreateFixture(&shape, 1.0f);
            }
        }
    }

    // Implement contact listener.
    void BeginContact(b2Contact* contact)
    {
        b2Fixture* fixtureA = contact->GetFixtureA();
        b2Fixture* fixtureB = contact->GetFixtureB();

        if (fixtureA == m_sensor)
        {
            void* userData = fixtureB->GetBody()->GetUserData();
            if (userData)
            {
                bool* touching = (bool*)userData;
                *touching = true;
            }
        }

        if (fixtureB == m_sensor)
        {
            void* userData = fixtureA->GetBody()->GetUserData();
            if (userData)
            {
                bool* touching = (bool*)userData;
                *touching = true;
            }
        }
    }

    // Implement contact listener.
    void EndContact(b2Contact* contact)
    {
        b2Fixture* fixtureA = contact->GetFixtureA();
        b2Fixture* fixtureB = contact->GetFixtureB();

        if (fixtureA == m_sensor)
        {
            void* userData = fixtureB->GetBody()->GetUserData();
            if (userData)
            {
                bool* touching = (bool*)userData;
                *touching = false;
            }
        }

        if (fixtureB == m_sensor)
        {
            void* userData = fixtureA->GetBody()->GetUserData();
            if (userData)
            {
                bool* touching = (bool*)userData;
                *touching = false;
            }
        }
    }

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

        // Traverse the contact results. Apply a force on shapes
        // that overlap the sensor.
        for (int32 i = 0; i < e_count; ++i)
        {
            if (m_touching[i] == false)
            {
                continue;
            }

            b2Body* body = m_bodies[i];
            b2Body* ground = m_sensor->GetBody();

            b2CircleShape* circle = (b2CircleShape*)m_sensor->GetShape();
            b2Vec2 center = ground->GetWorldPoint(circle->m_p);

            b2Vec2 position = body->GetPosition();

            b2Vec2 d = center - position;
            if (d.LengthSquared() < FLT_EPSILON * FLT_EPSILON)
            {
                continue;
            }

            d.Normalize();
            b2Vec2 F = 100.0f * d;
            body->ApplyForce(F, position);
        }
    }

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

    b2Fixture* m_sensor;
    b2Body* m_bodies[e_count];
    bool m_touching[e_count];
};

#endif