Physics.h

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/*
===========================================================================

Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company. 

This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).  

Doom 3 Source Code is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Doom 3 Source Code is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Doom 3 Source Code.  If not, see <http://www.gnu.org/licenses/>.

In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code.  If not, please request a copy in writing from id Software at the address below.

If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.

===========================================================================
*/

#ifndef __PHYSICS_H__
#define __PHYSICS_H__

/*
===============================================================================

        Physics abstract class

        A physics object is a tool to manipulate the position and orientation of
        an entity. The physics object is a container for idClipModels used for
        collision detection. The physics deals with moving these collision models
        through the world according to the laws of physics or other rules.

        The mass of a clip model is the volume of the clip model times the density.
        An arbitrary mass can however be set for specific clip models or the
        whole physics object. The contents of a clip model is a set of bit flags
        that define the contents. The clip mask defines the contents a clip model
        collides with.

        The linear velocity of a physics object is a vector that defines the
        translation of the center of mass in units per second. The angular velocity
        of a physics object is a vector that passes through the center of mass. The
        direction of this vector defines the axis of rotation and the magnitude
        defines the rate of rotation about the axis in radians per second.
        The gravity is the change in velocity per second due to gravitational force.

        Entities update their visual position and orientation from the physics
        using GetOrigin() and GetAxis(). Direct origin and axis changes of
        entities should go through the physics. In other words the physics origin
        and axis are updated first and the entity updates it's visual position
        from the physics.

===============================================================================
*/

#define CONTACT_EPSILON                 0.25f                           // maximum contact seperation distance

class idEntity;

typedef struct impactInfo_s {
        float                                           invMass;                        // inverse mass
        idMat3                                          invInertiaTensor;       // inverse inertia tensor
        idVec3                                          position;                       // impact position relative to center of mass
        idVec3                                          velocity;                       // velocity at the impact position
} impactInfo_t;


class idPhysics : public idClass {

public:
        ABSTRACT_PROTOTYPE( idPhysics );

        virtual                                         ~idPhysics( void );
        static int                                      SnapTimeToPhysicsFrame( int t );

        // Must not be virtual
        void                                            Save( idSaveGame *savefile ) const;
        void                                            Restore( idRestoreGame *savefile );

public: // common physics interface
                                                                // set pointer to entity using physics
        virtual void                            SetSelf( idEntity *e ) = 0;
                                                                // clip models
        virtual void                            SetClipModel( idClipModel *model, float density, int id = 0, bool freeOld = true ) = 0;
        virtual void                            SetClipBox( const idBounds &bounds, float density );
        virtual idClipModel *           GetClipModel( int id = 0 ) const = 0;
        virtual int                                     GetNumClipModels( void ) const = 0;
                                                                // get/set the mass of a specific clip model or the whole physics object
        virtual void                            SetMass( float mass, int id = -1 ) = 0;
        virtual float                           GetMass( int id = -1 ) const = 0;
                                                                // get/set the contents of a specific clip model or the whole physics object
        virtual void                            SetContents( int contents, int id = -1 ) = 0;
        virtual int                                     GetContents( int id = -1 ) const = 0;
                                                                // get/set the contents a specific clip model or the whole physics object collides with
        virtual void                            SetClipMask( int mask, int id = -1 ) = 0;
        virtual int                                     GetClipMask( int id = -1 ) const = 0;
                                                                // get the bounds of a specific clip model or the whole physics object
        virtual const idBounds &        GetBounds( int id = -1 ) const = 0;
        virtual const idBounds &        GetAbsBounds( int id = -1 ) const = 0;
                                                                // evaluate the physics with the given time step, returns true if the object moved
        virtual bool                            Evaluate( int timeStepMSec, int endTimeMSec ) = 0;
                                                                // update the time without moving
        virtual void                            UpdateTime( int endTimeMSec ) = 0;
                                                                // get the last physics update time
        virtual int                                     GetTime( void ) const = 0;
                                                                // collision interaction between different physics objects
        virtual void                            GetImpactInfo( const int id, const idVec3 &point, impactInfo_t *info ) const = 0;
        virtual void                            ApplyImpulse( const int id, const idVec3 &point, const idVec3 &impulse ) = 0;
        virtual void                            AddForce( const int id, const idVec3 &point, const idVec3 &force ) = 0;
        virtual void                            Activate( void ) = 0;
        virtual void                            PutToRest( void ) = 0;
        virtual bool                            IsAtRest( void ) const = 0;
        virtual int                                     GetRestStartTime( void ) const = 0;
        virtual bool                            IsPushable( void ) const = 0;
                                                                // save and restore the physics state
        virtual void                            SaveState( void ) = 0;
        virtual void                            RestoreState( void ) = 0;
                                                                // set the position and orientation in master space or world space if no master set
        virtual void                            SetOrigin( const idVec3 &newOrigin, int id = -1 ) = 0;
        virtual void                            SetAxis( const idMat3 &newAxis, int id = -1 ) = 0;
                                                                // translate or rotate the physics object in world space
        virtual void                            Translate( const idVec3 &translation, int id = -1 ) = 0;
        virtual void                            Rotate( const idRotation &rotation, int id = -1 ) = 0;
                                                                // get the position and orientation in world space
        virtual const idVec3 &          GetOrigin( int id = 0 ) const = 0;
        virtual const idMat3 &          GetAxis( int id = 0 ) const = 0;
                                                                // set linear and angular velocity
        virtual void                            SetLinearVelocity( const idVec3 &newLinearVelocity, int id = 0 ) = 0;
        virtual void                            SetAngularVelocity( const idVec3 &newAngularVelocity, int id = 0 ) = 0;
                                                                // get linear and angular velocity
        virtual const idVec3 &          GetLinearVelocity( int id = 0 ) const = 0;
        virtual const idVec3 &          GetAngularVelocity( int id = 0 ) const = 0;
                                                                // gravity
        virtual void                            SetGravity( const idVec3 &newGravity ) = 0;
        virtual const idVec3 &          GetGravity( void ) const = 0;
        virtual const idVec3 &          GetGravityNormal( void ) const = 0;
                                                                // get first collision when translating or rotating this physics object
        virtual void                            ClipTranslation( trace_t &results, const idVec3 &translation, const idClipModel *model ) const = 0;
        virtual void                            ClipRotation( trace_t &results, const idRotation &rotation, const idClipModel *model ) const = 0;
        virtual int                                     ClipContents( const idClipModel *model ) const = 0;
                                                                // disable/enable the clip models contained by this physics object
        virtual void                            DisableClip( void ) = 0;
        virtual void                            EnableClip( void ) = 0;
                                                                // link/unlink the clip models contained by this physics object
        virtual void                            UnlinkClip( void ) = 0;
        virtual void                            LinkClip( void ) = 0;
                                                                // contacts
        virtual bool                            EvaluateContacts( void ) = 0;
        virtual int                                     GetNumContacts( void ) const = 0;
        virtual const contactInfo_t &GetContact( int num ) const = 0;
        virtual void                            ClearContacts( void ) = 0;
        virtual void                            AddContactEntity( idEntity *e ) = 0;
        virtual void                            RemoveContactEntity( idEntity *e ) = 0;
                                                                // ground contacts
        virtual bool                            HasGroundContacts( void ) const = 0;
        virtual bool                            IsGroundEntity( int entityNum ) const = 0;
        virtual bool                            IsGroundClipModel( int entityNum, int id ) const = 0;
                                                                // set the master entity for objects bound to a master
        virtual void                            SetMaster( idEntity *master, const bool orientated = true ) = 0;
                                                                // set pushed state
        virtual void                            SetPushed( int deltaTime ) = 0;
        virtual const idVec3 &          GetPushedLinearVelocity( const int id = 0 ) const = 0;
        virtual const idVec3 &          GetPushedAngularVelocity( const int id = 0 ) const = 0;
                                                                // get blocking info, returns NULL if the object is not blocked
        virtual const trace_t *         GetBlockingInfo( void ) const = 0;
        virtual idEntity *                      GetBlockingEntity( void ) const = 0;
                                                                // movement end times in msec for reached events at the end of predefined motion
        virtual int                                     GetLinearEndTime( void ) const = 0;
        virtual int                                     GetAngularEndTime( void ) const = 0;
                                                                // networking
        virtual void                            WriteToSnapshot( idBitMsgDelta &msg ) const = 0;
        virtual void                            ReadFromSnapshot( const idBitMsgDelta &msg ) = 0;
};

#endif /* !__PHYSICS_H__ */