axmol/external/Box2D/Dynamics/b2Fixture.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 B2_FIXTURE_H
#define B2_FIXTURE_H

#include <Box2D/Dynamics/b2Body.h>
#include <Box2D/Collision/b2Collision.h>
#include <Box2D/Collision/Shapes/b2Shape.h>

class b2BlockAllocator;
class b2Body;
class b2BroadPhase;
class b2Fixture;

/// This holds contact filtering data.
struct b2Filter
{
    b2Filter()
    {
        categoryBits = 0x0001;
        maskBits = 0xFFFF;
        groupIndex = 0;
    }

    /// The collision category bits. Normally you would just set one bit.
    uint16 categoryBits;

    /// The collision mask bits. This states the categories that this
    /// shape would accept for collision.
    uint16 maskBits;

    /// Collision groups allow a certain group of objects to never collide (negative)
    /// or always collide (positive). Zero means no collision group. Non-zero group
    /// filtering always wins against the mask bits.
    int16 groupIndex;
};

/// A fixture definition is used to create a fixture. This class defines an
/// abstract fixture definition. You can reuse fixture definitions safely.
struct b2FixtureDef
{
    /// The constructor sets the default fixture definition values.
    b2FixtureDef()
    {
        shape = NULL;
        userData = NULL;
        friction = 0.2f;
        restitution = 0.0f;
        density = 0.0f;
        isSensor = false;
    }

    /// The shape, this must be set. The shape will be cloned, so you
    /// can create the shape on the stack.
    const b2Shape* shape;

    /// Use this to store application specific fixture data.
    void* userData;

    /// The friction coefficient, usually in the range [0,1].
    float32 friction;

    /// The restitution (elasticity) usually in the range [0,1].
    float32 restitution;

    /// The density, usually in kg/m^2.
    float32 density;

    /// A sensor shape collects contact information but never generates a collision
    /// response.
    bool isSensor;

    /// Contact filtering data.
    b2Filter filter;
};

/// This proxy is used internally to connect fixtures to the broad-phase.
struct b2FixtureProxy
{
    b2AABB aabb;
    b2Fixture* fixture;
    int32 childIndex;
    int32 proxyId;
};

/// A fixture is used to attach a shape to a body for collision detection. A fixture
/// inherits its transform from its parent. Fixtures hold additional non-geometric data
/// such as friction, collision filters, etc.
/// Fixtures are created via b2Body::CreateFixture.
/// @warning you cannot reuse fixtures.
class b2Fixture
{
public:
    /// Get the type of the child shape. You can use this to down cast to the concrete shape.
    /// @return the shape type.
    b2Shape::Type GetType() const;

    /// Get the child shape. You can modify the child shape, however you should not change the
    /// number of vertices because this will crash some collision caching mechanisms.
    /// Manipulating the shape may lead to non-physical behavior.
    b2Shape* GetShape();
    const b2Shape* GetShape() const;

    /// Set if this fixture is a sensor.
    void SetSensor(bool sensor);

    /// Is this fixture a sensor (non-solid)?
    /// @return the true if the shape is a sensor.
    bool IsSensor() const;

    /// Set the contact filtering data. This will not update contacts until the next time
    /// step when either parent body is active and awake.
    /// This automatically calls Refilter.
    void SetFilterData(const b2Filter& filter);

    /// Get the contact filtering data.
    const b2Filter& GetFilterData() const;

    /// Call this if you want to establish collision that was previously disabled by b2ContactFilter::ShouldCollide.
    void Refilter();

    /// Get the parent body of this fixture. This is NULL if the fixture is not attached.
    /// @return the parent body.
    b2Body* GetBody();
    const b2Body* GetBody() const;

    /// Get the next fixture in the parent body's fixture list.
    /// @return the next shape.
    b2Fixture* GetNext();
    const b2Fixture* GetNext() const;

    /// Get the user data that was assigned in the fixture definition. Use this to
    /// store your application specific data.
    void* GetUserData() const;

    /// Set the user data. Use this to store your application specific data.
    void SetUserData(void* data);

    /// Test a point for containment in this fixture.
    /// @param p a point in world coordinates.
    bool TestPoint(const b2Vec2& p) const;

    /// Cast a ray against this shape.
    /// @param output the ray-cast results.
    /// @param input the ray-cast input parameters.
    bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, int32 childIndex) const;

    /// Get the mass data for this fixture. The mass data is based on the density and
    /// the shape. The rotational inertia is about the shape's origin. This operation
    /// may be expensive.
    void GetMassData(b2MassData* massData) const;

    /// Set the density of this fixture. This will _not_ automatically adjust the mass
    /// of the body. You must call b2Body::ResetMassData to update the body's mass.
    void SetDensity(float32 density);

    /// Get the density of this fixture.
    float32 GetDensity() const;

    /// Get the coefficient of friction.
    float32 GetFriction() const;

    /// Set the coefficient of friction. This will _not_ change the friction of
    /// existing contacts.
    void SetFriction(float32 friction);

    /// Get the coefficient of restitution.
    float32 GetRestitution() const;

    /// Set the coefficient of restitution. This will _not_ change the restitution of
    /// existing contacts.
    void SetRestitution(float32 restitution);

    /// Get the fixture's AABB. This AABB may be enlarge and/or stale.
    /// If you need a more accurate AABB, compute it using the shape and
    /// the body transform.
    const b2AABB& GetAABB(int32 childIndex) const;

    /// Dump this fixture to the log file.
    void Dump(int32 bodyIndex);

protected:

    friend class b2Body;
    friend class b2World;
    friend class b2Contact;
    friend class b2ContactManager;

    b2Fixture();

    // We need separation create/destroy functions from the constructor/destructor because
    // the destructor cannot access the allocator (no destructor arguments allowed by C++).
    void Create(b2BlockAllocator* allocator, b2Body* body, const b2FixtureDef* def);
    void Destroy(b2BlockAllocator* allocator);

    // These support body activation/deactivation.
    void CreateProxies(b2BroadPhase* broadPhase, const b2Transform& xf);
    void DestroyProxies(b2BroadPhase* broadPhase);

    void Synchronize(b2BroadPhase* broadPhase, const b2Transform& xf1, const b2Transform& xf2);

    float32 m_density;

    b2Fixture* m_next;
    b2Body* m_body;

    b2Shape* m_shape;

    float32 m_friction;
    float32 m_restitution;

    b2FixtureProxy* m_proxies;
    int32 m_proxyCount;

    b2Filter m_filter;

    bool m_isSensor;

    void* m_userData;
};

inline b2Shape::Type b2Fixture::GetType() const
{
    return m_shape->GetType();
}

inline b2Shape* b2Fixture::GetShape()
{
    return m_shape;
}

inline const b2Shape* b2Fixture::GetShape() const
{
    return m_shape;
}

inline bool b2Fixture::IsSensor() const
{
    return m_isSensor;
}

inline const b2Filter& b2Fixture::GetFilterData() const
{
    return m_filter;
}

inline void* b2Fixture::GetUserData() const
{
    return m_userData;
}

inline void b2Fixture::SetUserData(void* data)
{
    m_userData = data;
}

inline b2Body* b2Fixture::GetBody()
{
    return m_body;
}

inline const b2Body* b2Fixture::GetBody() const
{
    return m_body;
}

inline b2Fixture* b2Fixture::GetNext()
{
    return m_next;
}

inline const b2Fixture* b2Fixture::GetNext() const
{
    return m_next;
}

inline void b2Fixture::SetDensity(float32 density)
{
    b2Assert(b2IsValid(density) && density >= 0.0f);
    m_density = density;
}

inline float32 b2Fixture::GetDensity() const
{
    return m_density;
}

inline float32 b2Fixture::GetFriction() const
{
    return m_friction;
}

inline void b2Fixture::SetFriction(float32 friction)
{
    m_friction = friction;
}

inline float32 b2Fixture::GetRestitution() const
{
    return m_restitution;
}

inline void b2Fixture::SetRestitution(float32 restitution)
{
    m_restitution = restitution;
}

inline bool b2Fixture::TestPoint(const b2Vec2& p) const
{
    return m_shape->TestPoint(m_body->GetTransform(), p);
}

inline bool b2Fixture::RayCast(b2RayCastOutput* output, const b2RayCastInput& input, int32 childIndex) const
{
    return m_shape->RayCast(output, input, m_body->GetTransform(), childIndex);
}

inline void b2Fixture::GetMassData(b2MassData* massData) const
{
    m_shape->ComputeMass(massData, m_density);
}

inline const b2AABB& b2Fixture::GetAABB(int32 childIndex) const
{
    b2Assert(0 <= childIndex && childIndex < m_proxyCount);
    return m_proxies[childIndex].aabb;
}

#endif