IEngineTrace.h

enum TraceType_t /* Taken from GamerFood's TraceEngine. Credits to him! */
{
    TRACE_EVERYTHING = 0,
    TRACE_WORLD_ONLY,				// NOTE: This does *not* test static props!!!
    TRACE_ENTITIES_ONLY,			// NOTE: This version will *not* test static props
    TRACE_EVERYTHING_FILTER_PROPS,	// NOTE: This version will pass the IHandleEntity for props through the filter, unlike all other filters
};

struct Ray_t
{
    Ray_t( ) { }
    
    VectorAligned		m_Start;
    VectorAligned		m_Delta;
    VectorAligned		m_StartOffset;
    VectorAligned		m_Extents;
    const matrix3x4_t	*m_pWorldAxisTransform;
    bool				m_IsRay;
    bool				m_IsSwept;
    
    void Init( Vector vecStart, Vector vecEnd )
    {
        m_Delta = VectorAligned( vecEnd - vecStart );
        m_IsSwept = ( m_Delta.LengthSqr( ) != 0 );
        m_Extents.Zero( );
        m_pWorldAxisTransform = NULL;
        m_IsRay = true;
        m_StartOffset.Zero( );
        m_Start = vecStart;
    }
};


class ITraceFilter
{
public:
    virtual bool ShouldHitEntity( C_BaseEntity* pEntityHandle, int contentsMask )
    {
        return !( pEntityHandle == pSkip );
    }
    virtual TraceType_t	GetTraceType( )
    {
        return TRACE_EVERYTHING;
    }
    void* pSkip;
};

class CTraceFilter : public ITraceFilter
{
public:
    virtual bool ShouldHitEntity( C_BaseEntity* pEntityHandle, int contentsMask )
    {
        return !( pEntityHandle == pSkip );
    }
    
    virtual TraceType_t	GetTraceType( ) const
    {
        return TRACE_EVERYTHING;
    }
    void* pSkip;
};

class CTraceFilterSkipTwoEntities : public ITraceFilter
{
public:
    CTraceFilterSkipTwoEntities( void *pPassEnt1, void *pPassEnt2 )
    {
        pPassEntity1 = pPassEnt1;
        pPassEntity2 = pPassEnt2;
    }
    
    virtual bool ShouldHitEntity( C_BaseEntity *pEntityHandle, int contentsMask )
    {
        return !( pEntityHandle == pPassEntity1 || pEntityHandle == pPassEntity2 );
    }
    
    virtual TraceType_t GetTraceType( ) const
    {
        return TRACE_EVERYTHING;
    }
    
    void *pPassEntity1;
    void *pPassEntity2;
};

typedef bool( *ShouldHitFunc_t )( IHandleEntity *pHandleEntity, int contentsMask );

class CTraceFilterSimple : public CTraceFilter
{
public:
    // It does have a base, but we'll never network anything below here..
    CTraceFilterSimple( const IHandleEntity *passentity, int collisionGroup, ShouldHitFunc_t pExtraShouldHitCheckFn = NULL );
    virtual bool ShouldHitEntity( IHandleEntity *pHandleEntity, int contentsMask );
    virtual void SetPassEntity( const IHandleEntity *pPassEntity ) { m_pPassEnt = pPassEntity; }
    virtual void SetCollisionGroup( int iCollisionGroup ) { m_collisionGroup = iCollisionGroup; }
    
    const IHandleEntity *GetPassEntity( void ){ return m_pPassEnt; }
    
private:
    const IHandleEntity *m_pPassEnt;
    int m_collisionGroup;
    ShouldHitFunc_t m_pExtraShouldHitCheckFunction;
    
};

class CBaseTrace
{
public:
    Vector			startpos;
    Vector			endpos;
    cplane_t		plane;
    
    float			fraction;
    
    int				contents;
    unsigned short	dispFlags;
    
    bool			allsolid;
    bool			startsolid;
    
    CBaseTrace( ) {}
};

struct csurface_t
{
    const char*		name;
    short			surfaceProps;
    unsigned short	flags;
};

class CGameTrace : public CBaseTrace
{
public:
    bool                    DidHitWorld() const;
    bool                    DidHitNonWorldEntity() const;
    int                     GetEntityIndex() const;
    bool                    DidHit() const;
    bool					IsVisible() const;
    
public:
    
    float                   fractionleftsolid;
    csurface_t              surface;
    int                     hitgroup;
    short                   physicsbone;
    unsigned short          worldSurfaceIndex;
    C_BaseEntity*            m_pEnt;
    int                     hitbox;
    
    CGameTrace() { }
    
private:
    CGameTrace( const CGameTrace& vOther );
};

typedef CGameTrace trace_t;

class IEngineTrace {
public:
    // Returns the contents mask + entity at a particular world-space position
    virtual int GetPointContents(const Vector &vecAbsPosition, int contentsMask = MASK_ALL, IHandleEntity** ppEntity = NULL) = 0;
    
    // Returns the contents mask of the world only @ the world-space position (static props are ignored)
    virtual int GetPointContents_WorldOnly(const Vector &vecAbsPosition, int contentsMask = MASK_ALL) = 0;
    
    // Get the point contents, but only test the specific entity. This works
    // on static props and brush models.
    //
    // If the entity isn't a static prop or a brush model, it returns CONTENTS_EMPTY and sets
    // bFailed to true if bFailed is non-null.
    virtual int GetPointContents_Collideable(ICollideable *pCollide, const Vector &vecAbsPosition) = 0;
    
    // Traces a ray against a particular entity
    virtual void ClipRayToEntity(const Ray_t &ray, unsigned int fMask, IHandleEntity *pEnt, trace_t *pTrace) = 0;
    
    // Traces a ray against a particular entity
    virtual void ClipRayToCollideable(const Ray_t &ray, unsigned int fMask, ICollideable *pCollide, trace_t *pTrace) = 0;
    
    // A version that simply accepts a ray (can work as a traceline or tracehull)
    virtual void TraceRay(const Ray_t &ray, unsigned int fMask, ITraceFilter *pTraceFilter, trace_t *pTrace) = 0;
};