b2_contact.h

// MIT License
 
// Copyright (c) 2019 Erin Catto
 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
 
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
 
#ifndef B2_CONTACT_H
#define B2_CONTACT_H
 
#include "b2_api.h"
#include "b2_collision.h"
#include "b2_fixture.h"
#include "b2_math.h"
#include "b2_shape.h"
 
class b2Body;
class b2Contact;
class b2Fixture;
class b2World;
class b2BlockAllocator;
class b2StackAllocator;
class b2ContactListener;
 
inline float b2MixFriction(float friction1, float friction2)
{
    return b2Sqrt(friction1 * friction2);
}
 
inline float b2MixRestitution(float restitution1, float restitution2)
{
    return restitution1 > restitution2 ? restitution1 : restitution2;
}
 
inline float b2MixRestitutionThreshold(float threshold1, float threshold2)
{
    return threshold1 < threshold2 ? threshold1 : threshold2;
}
 
typedef b2Contact* b2ContactCreateFcn(  b2Fixture* fixtureA, int32 indexA,
                                        b2Fixture* fixtureB, int32 indexB,
                                        b2BlockAllocator* allocator);
typedef void b2ContactDestroyFcn(b2Contact* contact, b2BlockAllocator* allocator);
 
struct B2_API b2ContactRegister
{
    b2ContactCreateFcn* createFcn;
    b2ContactDestroyFcn* destroyFcn;
    bool primary;
};
 
struct B2_API b2ContactEdge
{
    b2Body* other;          
    b2Contact* contact;     
    b2ContactEdge* prev;    
    b2ContactEdge* next;    
};
 
class B2_API b2Contact
{
public:
 
    b2Manifold* GetManifold();
    const b2Manifold* GetManifold() const;
 
    void GetWorldManifold(b2WorldManifold* worldManifold) const;
 
    bool IsTouching() const;
 
    void SetEnabled(bool flag);
 
    bool IsEnabled() const;
 
    b2Contact* GetNext();
    const b2Contact* GetNext() const;
 
    b2Fixture* GetFixtureA();
    const b2Fixture* GetFixtureA() const;
 
    int32 GetChildIndexA() const;
 
    b2Fixture* GetFixtureB();
    const b2Fixture* GetFixtureB() const;
 
    int32 GetChildIndexB() const;
 
    void SetFriction(float friction);
 
    float GetFriction() const;
 
    void ResetFriction();
 
    void SetRestitution(float restitution);
 
    float GetRestitution() const;
 
    void ResetRestitution();
 
    void SetRestitutionThreshold(float threshold);
 
    float GetRestitutionThreshold() const;
 
    void ResetRestitutionThreshold();
 
    void SetTangentSpeed(float speed);
 
    float GetTangentSpeed() const;
 
    virtual void Evaluate(b2Manifold* manifold, const b2Transform& xfA, const b2Transform& xfB) = 0;
 
protected:
    friend class b2ContactManager;
    friend class b2World;
    friend class b2ContactSolver;
    friend class b2Body;
    friend class b2Fixture;
 
    // Flags stored in m_flags
    enum
    {
        // Used when crawling contact graph when forming islands.
        e_islandFlag        = 0x0001,
 
        // Set when the shapes are touching.
        e_touchingFlag      = 0x0002,
 
        // This contact can be disabled (by user)
        e_enabledFlag       = 0x0004,
 
        // This contact needs filtering because a fixture filter was changed.
        e_filterFlag        = 0x0008,
 
        // This bullet contact had a TOI event
        e_bulletHitFlag     = 0x0010,
 
        // This contact has a valid TOI in m_toi
        e_toiFlag           = 0x0020
    };
 
    void FlagForFiltering();
 
    static void AddType(b2ContactCreateFcn* createFcn, b2ContactDestroyFcn* destroyFcn,
                        b2Shape::Type typeA, b2Shape::Type typeB);
    static void InitializeRegisters();
    static b2Contact* Create(b2Fixture* fixtureA, int32 indexA, b2Fixture* fixtureB, int32 indexB, b2BlockAllocator* allocator);
    static void Destroy(b2Contact* contact, b2Shape::Type typeA, b2Shape::Type typeB, b2BlockAllocator* allocator);
    static void Destroy(b2Contact* contact, b2BlockAllocator* allocator);
 
    b2Contact() : m_fixtureA(nullptr), m_fixtureB(nullptr) {}
    b2Contact(b2Fixture* fixtureA, int32 indexA, b2Fixture* fixtureB, int32 indexB);
    virtual ~b2Contact() {}
 
    void Update(b2ContactListener* listener);
 
    static b2ContactRegister s_registers[b2Shape::e_typeCount][b2Shape::e_typeCount];
    static bool s_initialized;
 
    uint32 m_flags;
 
    // World pool and list pointers.
    b2Contact* m_prev;
    b2Contact* m_next;
 
    // Nodes for connecting bodies.
    b2ContactEdge m_nodeA;
    b2ContactEdge m_nodeB;
 
    b2Fixture* m_fixtureA;
    b2Fixture* m_fixtureB;
 
    int32 m_indexA;
    int32 m_indexB;
 
    b2Manifold m_manifold;
 
    int32 m_toiCount;
    float m_toi;
 
    float m_friction;
    float m_restitution;
    float m_restitutionThreshold;
 
    float m_tangentSpeed;
};
 
inline b2Manifold* b2Contact::GetManifold()
{
    return &m_manifold;
}
 
inline const b2Manifold* b2Contact::GetManifold() const
{
    return &m_manifold;
}
 
inline void b2Contact::GetWorldManifold(b2WorldManifold* worldManifold) const
{
    const b2Body* bodyA = m_fixtureA->GetBody();
    const b2Body* bodyB = m_fixtureB->GetBody();
    const b2Shape* shapeA = m_fixtureA->GetShape();
    const b2Shape* shapeB = m_fixtureB->GetShape();
 
    worldManifold->Initialize(&m_manifold, bodyA->GetTransform(), shapeA->m_radius, bodyB->GetTransform(), shapeB->m_radius);
}
 
inline void b2Contact::SetEnabled(bool flag)
{
    if (flag)
    {
        m_flags |= e_enabledFlag;
    }
    else
    {
        m_flags &= ~e_enabledFlag;
    }
}
 
inline bool b2Contact::IsEnabled() const
{
    return (m_flags & e_enabledFlag) == e_enabledFlag;
}
 
inline bool b2Contact::IsTouching() const
{
    return (m_flags & e_touchingFlag) == e_touchingFlag;
}
 
inline b2Contact* b2Contact::GetNext()
{
    return m_next;
}
 
inline const b2Contact* b2Contact::GetNext() const
{
    return m_next;
}
 
inline b2Fixture* b2Contact::GetFixtureA()
{
    return m_fixtureA;
}
 
inline const b2Fixture* b2Contact::GetFixtureA() const
{
    return m_fixtureA;
}
 
inline b2Fixture* b2Contact::GetFixtureB()
{
    return m_fixtureB;
}
 
inline int32 b2Contact::GetChildIndexA() const
{
    return m_indexA;
}
 
inline const b2Fixture* b2Contact::GetFixtureB() const
{
    return m_fixtureB;
}
 
inline int32 b2Contact::GetChildIndexB() const
{
    return m_indexB;
}
 
inline void b2Contact::FlagForFiltering()
{
    m_flags |= e_filterFlag;
}
 
inline void b2Contact::SetFriction(float friction)
{
    m_friction = friction;
}
 
inline float b2Contact::GetFriction() const
{
    return m_friction;
}
 
inline void b2Contact::ResetFriction()
{
    m_friction = b2MixFriction(m_fixtureA->m_friction, m_fixtureB->m_friction);
}
 
inline void b2Contact::SetRestitution(float restitution)
{
    m_restitution = restitution;
}
 
inline float b2Contact::GetRestitution() const
{
    return m_restitution;
}
 
inline void b2Contact::ResetRestitution()
{
    m_restitution = b2MixRestitution(m_fixtureA->m_restitution, m_fixtureB->m_restitution);
}
 
inline void b2Contact::SetRestitutionThreshold(float threshold)
{
    m_restitutionThreshold = threshold;
}
 
inline float b2Contact::GetRestitutionThreshold() const
{
    return m_restitutionThreshold;
}
 
inline void b2Contact::ResetRestitutionThreshold()
{
    m_restitutionThreshold = b2MixRestitutionThreshold(m_fixtureA->m_restitutionThreshold, m_fixtureB->m_restitutionThreshold);
}
 
inline void b2Contact::SetTangentSpeed(float speed)
{
    m_tangentSpeed = speed;
}
 
inline float b2Contact::GetTangentSpeed() const
{
    return m_tangentSpeed;
}
 
#endif