oxygine-framework/examples/DemoBox2D/src/example.cpp

#include "oxygine-framework.h"
#include "Box2D/Box2D.h"
#include "Box2DDebugDraw.h"

using namespace oxygine;

//it is our resources
//in real project you would have more than one Resources declarations. It is important on mobile devices with limited memory and you would load/unload them
Resources gameResources;

//DECLARE_SMART is helper, it does forward declaration and declares intrusive_ptr typedef for your class
DECLARE_SMART(MainActor, spMainActor);


const float SCALE = 100.0f;
b2Vec2 convert(const Vector2& pos)
{
    return b2Vec2(pos.x / SCALE, pos.y / SCALE);
}

Vector2 convert(const b2Vec2& pos)
{
    return Vector2(pos.x * SCALE, pos.y * SCALE);
}


DECLARE_SMART(Circle, spCircle);
class Circle : public Sprite
{
public:
    Circle(b2World* world, const Vector2& pos, float scale = 1)
    {
        setResAnim(gameResources.getResAnim("circle"));
        setAnchor(Vector2(0.5f, 0.5f));
        setTouchChildrenEnabled(false);

        b2BodyDef bodyDef;
        bodyDef.type = b2_dynamicBody;
        bodyDef.position = convert(pos);

        b2Body* body = world->CreateBody(&bodyDef);

        setUserData(body);

        setScale(scale);

        b2CircleShape shape;
        shape.m_radius = getWidth() / SCALE / 2 * scale;

        b2FixtureDef fixtureDef;
        fixtureDef.shape = &shape;
        fixtureDef.density = 1.0f;
        fixtureDef.friction = 0.3f;

        body->CreateFixture(&fixtureDef);
        body->SetUserData(this);
    }
};

DECLARE_SMART(Static, spStatic);
class Static : public Box9Sprite
{
public:
    Static(b2World* world, const RectF& rc)
    {
        //setHorizontalMode(Box9Sprite::TILING_FULL);
        //setVerticalMode(Box9Sprite::TILING_FULL);
        setResAnim(gameResources.getResAnim("pen"));
        setSize(rc.getSize());
        setPosition(rc.getLeftTop());
        setAnchor(Vector2(0.5f, 0.5f));

        b2BodyDef groundBodyDef;
        groundBodyDef.position = convert(getPosition());

        b2Body* groundBody = world->CreateBody(&groundBodyDef);

        b2PolygonShape groundBox;
        b2Vec2 sz = convert(getSize() / 2);
        groundBox.SetAsBox(sz.x, sz.y);
        groundBody->CreateFixture(&groundBox, 0.0f);
    }
};

class MainActor: public Actor
{
public:
    b2World* _world;
    spBox2DDraw _debugDraw;

    MainActor(): _world(0)
    {
        setSize(getStage()->getSize());

        spButton btn = new Button;
        btn->setX(getWidth() - btn->getWidth() - 3);
        btn->setY(3);
        btn->attachTo(this);
        btn->addEventListener(TouchEvent::CLICK, CLOSURE(this, &MainActor::showHideDebug));

        addEventListener(TouchEvent::CLICK, CLOSURE(this, &MainActor::click));


        _world = new b2World(b2Vec2(0, 10));


        spStatic ground = new Static(_world, RectF(getWidth() / 2, getHeight() - 10, getWidth() - 100, 30));
        addChild(ground);

        spCircle circle = new Circle(_world, getSize() / 2, 1);
        addChild(circle);
    }

    void doUpdate(const UpdateState& us)
    {
        //in real project you should make steps with fixed dt, check box2d documentation
        _world->Step(us.dt / 1000.0f, 6, 2);

        //update each body position on display
        b2Body* body = _world->GetBodyList();
        while (body)
        {
            Actor* actor = (Actor*)body->GetUserData();
            b2Body* next = body->GetNext();
            if (actor)
            {
                const b2Vec2& pos = body->GetPosition();
                actor->setPosition(convert(pos));
                actor->setRotation(body->GetAngle());

                //remove fallen bodies
                if (actor->getY() > getHeight() + 50)
                {
                    body->SetUserData(0);
                    _world->DestroyBody(body);

                    actor->detach();
                }
            }

            body = next;
        }
    }

    void showHideDebug(Event* event)
    {
        TouchEvent* te = safeCast<TouchEvent*>(event);
        te->stopsImmediatePropagation = true;
        if (_debugDraw)
        {
            _debugDraw->detach();
            _debugDraw = 0;
            return;
        }

        _debugDraw = new Box2DDraw;
        _debugDraw->SetFlags(b2Draw::e_shapeBit | b2Draw::e_jointBit | b2Draw::e_pairBit | b2Draw::e_centerOfMassBit);
        _debugDraw->attachTo(this);
        _debugDraw->setWorld(SCALE, _world);
        _debugDraw->setPriority(1);
    }

    void click(Event* event)
    {
        TouchEvent* te = safeCast<TouchEvent*>(event);

        if (event->target.get() == this)
        {
            spCircle circle = new Circle(_world, te->localPosition);
            circle->attachTo(this);
        }

        if (event->target->getUserData())
        {
            //shot to circle
            spActor actor = safeSpCast<Actor>(event->target);
            b2Body* body = (b2Body*)actor->getUserData();

            Vector2 dir = actor->getPosition() - te->localPosition;
            dir = dir / dir.length() * body->GetMass() * 200;

            body->ApplyForceToCenter(b2Vec2(dir.x, dir.y), true);

            spSprite sprite = new Sprite();
            sprite->setResAnim(gameResources.getResAnim("shot"));
            Vector2 local = actor->parent2local(te->localPosition);
            sprite->setPosition(local);
            sprite->setAnchor(Vector2(0.5f, 0.5f));
            sprite->attachTo(actor);
        }
    }
};

void example_preinit()
{
}

void example_init()
{
    //load xml file with resources definition
    gameResources.loadXML("res.xml");

    //lets create our client code simple actor
    //prefix 'sp' here means it is intrusive Smart Pointer
    //it would be deleted automatically when you lost ref to it
    spMainActor actor = new MainActor;
    //and add it to Stage as child
    getStage()->addChild(actor);
}

void example_destroy()
{
    gameResources.free();
}

void example_update()
{

}