Physics_RigidBody.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_RIGIDBODY_H__
#define __PHYSICS_RIGIDBODY_H__

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

        Rigid body physics

        Employs an impulse based dynamic simulation which is not very accurate but
        relatively fast and still reliable due to the continuous collision detection.

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

extern const float      RB_VELOCITY_MAX;
extern const int        RB_VELOCITY_TOTAL_BITS;
extern const int        RB_VELOCITY_EXPONENT_BITS;
extern const int        RB_VELOCITY_MANTISSA_BITS;

typedef struct rididBodyIState_s {
        idVec3                                  position;                                       // position of trace model
        idMat3                                  orientation;                            // orientation of trace model
        idVec3                                  linearMomentum;                         // translational momentum relative to center of mass
        idVec3                                  angularMomentum;                        // rotational momentum relative to center of mass
} rigidBodyIState_t;

typedef struct rigidBodyPState_s {
        int                                             atRest;                                         // set when simulation is suspended
        float                                   lastTimeStep;                           // length of last time step
        idVec3                                  localOrigin;                            // origin relative to master
        idMat3                                  localAxis;                                      // axis relative to master
        idVec6                                  pushVelocity;                           // push velocity
        idVec3                                  externalForce;                          // external force relative to center of mass
        idVec3                                  externalTorque;                         // external torque relative to center of mass
        rigidBodyIState_t               i;                                                      // state used for integration
} rigidBodyPState_t;

class idPhysics_RigidBody : public idPhysics_Base {

public:

        CLASS_PROTOTYPE( idPhysics_RigidBody );

                                                        idPhysics_RigidBody( void );
                                                        ~idPhysics_RigidBody( void );

        void                                    Save( idSaveGame *savefile ) const;
        void                                    Restore( idRestoreGame *savefile );

                                                        // initialisation
        void                                    SetFriction( const float linear, const float angular, const float contact );
        void                                    SetBouncyness( const float b );
                                                        // same as above but drop to the floor first
        void                                    DropToFloor( void );
                                                        // no contact determination and contact friction
        void                                    NoContact( void );
                                                        // enable/disable activation by impact
        void                                    EnableImpact( void );
        void                                    DisableImpact( void );

public: // common physics interface
        void                                    SetClipModel( idClipModel *model, float density, int id = 0, bool freeOld = true );
        idClipModel *                   GetClipModel( int id = 0 ) const;
        int                                             GetNumClipModels( void ) const;

        void                                    SetMass( float mass, int id = -1 );
        float                                   GetMass( int id = -1 ) const;

        void                                    SetContents( int contents, int id = -1 );
        int                                             GetContents( int id = -1 ) const;

        const idBounds &                GetBounds( int id = -1 ) const;
        const idBounds &                GetAbsBounds( int id = -1 ) const;

        bool                                    Evaluate( int timeStepMSec, int endTimeMSec );
        void                                    UpdateTime( int endTimeMSec );
        int                                             GetTime( void ) const;

        void                                    GetImpactInfo( const int id, const idVec3 &point, impactInfo_t *info ) const;
        void                                    ApplyImpulse( const int id, const idVec3 &point, const idVec3 &impulse );
        void                                    AddForce( const int id, const idVec3 &point, const idVec3 &force );
        void                                    Activate( void );
        void                                    PutToRest( void );
        bool                                    IsAtRest( void ) const;
        int                                             GetRestStartTime( void ) const;
        bool                                    IsPushable( void ) const;

        void                                    SaveState( void );
        void                                    RestoreState( void );

        void                                    SetOrigin( const idVec3 &newOrigin, int id = -1 );
        void                                    SetAxis( const idMat3 &newAxis, int id = -1 );

        void                                    Translate( const idVec3 &translation, int id = -1 );
        void                                    Rotate( const idRotation &rotation, int id = -1 );

        const idVec3 &                  GetOrigin( int id = 0 ) const;
        const idMat3 &                  GetAxis( int id = 0 ) const;

        void                                    SetLinearVelocity( const idVec3 &newLinearVelocity, int id = 0 );
        void                                    SetAngularVelocity( const idVec3 &newAngularVelocity, int id = 0 );

        const idVec3 &                  GetLinearVelocity( int id = 0 ) const;
        const idVec3 &                  GetAngularVelocity( int id = 0 ) const;

        void                                    ClipTranslation( trace_t &results, const idVec3 &translation, const idClipModel *model ) const;
        void                                    ClipRotation( trace_t &results, const idRotation &rotation, const idClipModel *model ) const;
        int                                             ClipContents( const idClipModel *model ) const;

        void                                    DisableClip( void );
        void                                    EnableClip( void );

        void                                    UnlinkClip( void );
        void                                    LinkClip( void );

        bool                                    EvaluateContacts( void );

        void                                    SetPushed( int deltaTime );
        const idVec3 &                  GetPushedLinearVelocity( const int id = 0 ) const;
        const idVec3 &                  GetPushedAngularVelocity( const int id = 0 ) const;

        void                                    SetMaster( idEntity *master, const bool orientated );

        void                                    WriteToSnapshot( idBitMsgDelta &msg ) const;
        void                                    ReadFromSnapshot( const idBitMsgDelta &msg );

private:
        // state of the rigid body
        rigidBodyPState_t               current;
        rigidBodyPState_t               saved;

        // rigid body properties
        float                                   linearFriction;                         // translational friction
        float                                   angularFriction;                        // rotational friction
        float                                   contactFriction;                        // friction with contact surfaces
        float                                   bouncyness;                                     // bouncyness
        idClipModel *                   clipModel;                                      // clip model used for collision detection

        // derived properties
        float                                   mass;                                           // mass of body
        float                                   inverseMass;                            // 1 / mass
        idVec3                                  centerOfMass;                           // center of mass of trace model
        idMat3                                  inertiaTensor;                          // mass distribution
        idMat3                                  inverseInertiaTensor;           // inverse inertia tensor

        idODE *                                 integrator;                                     // integrator
        bool                                    dropToFloor;                            // true if dropping to the floor and putting to rest
        bool                                    testSolid;                                      // true if testing for solid when dropping to the floor
        bool                                    noImpact;                                       // if true do not activate when another object collides
        bool                                    noContact;                                      // if true do not determine contacts and no contact friction

        // master
        bool                                    hasMaster;
        bool                                    isOrientated;

private:
        friend void                             RigidBodyDerivatives( const float t, const void *clientData, const float *state, float *derivatives );
        void                                    Integrate( const float deltaTime, rigidBodyPState_t &next );
        bool                                    CheckForCollisions( const float deltaTime, rigidBodyPState_t &next, trace_t &collision );
        bool                                    CollisionImpulse( const trace_t &collision, idVec3 &impulse );
        void                                    ContactFriction( float deltaTime );
        void                                    DropToFloorAndRest( void );
        bool                                    TestIfAtRest( void ) const;
        void                                    Rest( void );
        void                                    DebugDraw( void );
};

#endif /* !__PHYSICS_RIGIDBODY_H__ */