JUCE/examples/Demo/Source/Demos/Box2DTests/PolyShapes.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 POLY_SHAPES_H
#define POLY_SHAPES_H

/// This tests stacking. It also shows how to use b2World::Query
/// and b2TestOverlap.

const int32 k_maxBodies = 256;

/// This callback is called by b2World::QueryAABB. We find all the fixtures
/// that overlap an AABB. Of those, we use b2TestOverlap to determine which fixtures
/// overlap a circle. Up to 4 overlapped fixtures will be highlighted with a yellow border.
class PolyShapesCallback : public b2QueryCallback
{
public:

    enum
    {
        e_maxCount = 4
    };

    PolyShapesCallback()
    {
        m_count = 0;
    }

    void DrawFixture(b2Fixture* fixture)
    {
        b2Color color(0.95f, 0.95f, 0.6f);
        const b2Transform& xf = fixture->GetBody()->GetTransform();

        switch (fixture->GetType())
        {
        case b2Shape::e_circle:
            {
                b2CircleShape* circle = (b2CircleShape*)fixture->GetShape();

                b2Vec2 center = b2Mul(xf, circle->m_p);
                float32 radius = circle->m_radius;

                m_debugDraw->DrawCircle(center, radius, color);
            }
            break;

        case b2Shape::e_polygon:
            {
                b2PolygonShape* poly = (b2PolygonShape*)fixture->GetShape();
                int32 vertexCount = poly->m_vertexCount;
                b2Assert(vertexCount <= b2_maxPolygonVertices);
                b2Vec2 vertices[b2_maxPolygonVertices];

                for (int32 i = 0; i < vertexCount; ++i)
                {
                    vertices[i] = b2Mul(xf, poly->m_vertices[i]);
                }

                m_debugDraw->DrawPolygon(vertices, vertexCount, color);
            }
            break;

        default:
            break;
        }
    }

    /// Called for each fixture found in the query AABB.
    /// @return false to terminate the query.
    bool ReportFixture(b2Fixture* fixture)
    {
        if (m_count == e_maxCount)
        {
            return false;
        }

        b2Body* body = fixture->GetBody();
        b2Shape* shape = fixture->GetShape();

        bool overlap = b2TestOverlap(shape, 0, &m_circle, 0, body->GetTransform(), m_transform);

        if (overlap)
        {
            DrawFixture(fixture);
            ++m_count;
        }

        return true;
    }

    b2CircleShape m_circle;
    b2Transform m_transform;
    b2Draw* m_debugDraw;
    int32 m_count;
};

class PolyShapes : public Test
{
public:
    PolyShapes()
    {
        // Ground body
        {
            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);
        }

        {
            b2Vec2 vertices[3];
            vertices[0].Set(-0.5f, 0.0f);
            vertices[1].Set(0.5f, 0.0f);
            vertices[2].Set(0.0f, 1.5f);
            m_polygons[0].Set(vertices, 3);
        }

        {
            b2Vec2 vertices[3];
            vertices[0].Set(-0.1f, 0.0f);
            vertices[1].Set(0.1f, 0.0f);
            vertices[2].Set(0.0f, 1.5f);
            m_polygons[1].Set(vertices, 3);
        }

        {
            float32 w = 1.0f;
            float32 b = w / (2.0f + b2Sqrt(2.0f));
            float32 s = b2Sqrt(2.0f) * b;

            b2Vec2 vertices[8];
            vertices[0].Set(0.5f * s, 0.0f);
            vertices[1].Set(0.5f * w, b);
            vertices[2].Set(0.5f * w, b + s);
            vertices[3].Set(0.5f * s, w);
            vertices[4].Set(-0.5f * s, w);
            vertices[5].Set(-0.5f * w, b + s);
            vertices[6].Set(-0.5f * w, b);
            vertices[7].Set(-0.5f * s, 0.0f);

            m_polygons[2].Set(vertices, 8);
        }

        {
            m_polygons[3].SetAsBox(0.5f, 0.5f);
        }

        {
            m_circle.m_radius = 0.5f;
        }

        m_bodyIndex = 0;
        memset(m_bodies, 0, sizeof(m_bodies));
    }

    void Create(int32 index)
    {
        if (m_bodies[m_bodyIndex] != NULL)
        {
            m_world->DestroyBody(m_bodies[m_bodyIndex]);
            m_bodies[m_bodyIndex] = NULL;
        }

        b2BodyDef bd;
        bd.type = b2_dynamicBody;

        float32 x = RandomFloat(-2.0f, 2.0f);
        bd.position.Set(x, 10.0f);
        bd.angle = RandomFloat(-b2_pi, b2_pi);

        if (index == 4)
        {
            bd.angularDamping = 0.02f;
        }

        m_bodies[m_bodyIndex] = m_world->CreateBody(&bd);

        if (index < 4)
        {
            b2FixtureDef fd;
            fd.shape = m_polygons + index;
            fd.density = 1.0f;
            fd.friction = 0.3f;
            m_bodies[m_bodyIndex]->CreateFixture(&fd);
        }
        else
        {
            b2FixtureDef fd;
            fd.shape = &m_circle;
            fd.density = 1.0f;
            fd.friction = 0.3f;

            m_bodies[m_bodyIndex]->CreateFixture(&fd);
        }

        m_bodyIndex = (m_bodyIndex + 1) % k_maxBodies;
    }

    void DestroyBody()
    {
        for (int32 i = 0; i < k_maxBodies; ++i)
        {
            if (m_bodies[i] != NULL)
            {
                m_world->DestroyBody(m_bodies[i]);
                m_bodies[i] = NULL;
                return;
            }
        }
    }

    void Keyboard(unsigned char key)
    {
        switch (key)
        {
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
            Create(key - '1');
            break;

        case 'a':
            for (int32 i = 0; i < k_maxBodies; i += 2)
            {
                if (m_bodies[i])
                {
                    bool active = m_bodies[i]->IsActive();
                    m_bodies[i]->SetActive(!active);
                }
            }
            break;

        case 'd':
            DestroyBody();
            break;
        }
    }

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

        PolyShapesCallback callback;
        callback.m_circle.m_radius = 2.0f;
        callback.m_circle.m_p.Set(0.0f, 1.1f);
        callback.m_transform.SetIdentity();
        callback.m_debugDraw = &m_debugDraw;

        b2AABB aabb;
        callback.m_circle.ComputeAABB(&aabb, callback.m_transform, 0);

        m_world->QueryAABB(&callback, aabb);

        b2Color color(0.4f, 0.7f, 0.8f);
        m_debugDraw.DrawCircle(callback.m_circle.m_p, callback.m_circle.m_radius, color);

        m_debugDraw.DrawString(5, m_textLine, "Press 1-5 to drop stuff");
        m_textLine += 15;
        m_debugDraw.DrawString(5, m_textLine, "Press 'a' to (de)activate some bodies");
        m_textLine += 15;
        m_debugDraw.DrawString(5, m_textLine, "Press 'd' to destroy a body");
        m_textLine += 15;
    }

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

    int32 m_bodyIndex;
    b2Body* m_bodies[k_maxBodies];
    b2PolygonShape m_polygons[4];
    b2CircleShape m_circle;
};

#endif