/Users/frarees/Desktop/rv1/source/inc/Wheel.h

#ifndef __WHEEL_H__
#define __WHEEL_H__


// Skid mark stuff
typedef struct {
  VEC     Corner[4];
  VEC     Centre;
  long      RGB;
  VISIMASK    VisiMask;
} SKIDMARK;


typedef struct {
  long  Started;
  REAL  LastSmokeTime;

  VEC Pos;
  VEC Dir;
  VEC Normal;
  REAL  Width;

  MATERIAL *Material;
  SKIDMARK *CurrentSkid;
} SKIDMARK_START;

#ifdef _PSX
  #define SKID_MAX_SKIDS  (128)       // Max number of skids allowed
#else
  #define SKID_MAX_SKIDS  (1000)        // Max number of skids allowed
#endif

#define SKID_MAX_LEN  TO_LENGTH(Real(128))      // Max length of a skidmark
#define SKID_HALF_LEN TO_LENGTH(Real(64))     // Half the max length
#define SKID_MIN_LEN  TO_LENGTH(Real(10))     // Min length of a skidmark
#define SKID_MAX_DOT  (Real(0.98))    // Dot product of skid direction cannot change below this
#define SKID_RAISE    TO_LENGTH(Real(0.2))      // Distance above floor of skidmarks
#define SKID_FADE_NUM (100)       // number of skids to fade out
#define SKID_FADE_START (SKID_MAX_SKIDS - SKID_FADE_NUM)
#define SKID_FADE_FACTOR (2)        // Amount to reduce fading skids alpha by
#ifdef _PC
#define SKID_SMOKE_TIME (Real(0.03))    // Amount of time between smoke generations
#endif
#ifdef _N64
#define SKID_SMOKE_TIME (Real(0.01))    // Amount of time between smoke generations
#endif

// Spring Stuff
typedef struct {
  REAL  Stiffness;
  REAL  Damping;
  REAL  Restitution;
} SPRING;

#define SpringForce(spring, extension) \
  ( - (spring)->Stiffness * (extension) )


// WheelInfo: structure to hold initialisation data for a wheel
typedef struct {
  long  ModelNum;
  VEC Offset1;
  VEC Offset2;
  REAL  Radius;
  REAL  Mass;
  REAL  Gravity;
  REAL  Grip;
  REAL  StaticFriction;
  REAL  KineticFriction;
  REAL  AxleFriction;
  REAL  SteerRatio;
  REAL  EngineRatio;
  REAL  MaxPos;
  REAL  SkidWidth;

  bool  IsPresent;
  bool  IsTurnable;
  bool  IsPowered;

} WHEEL_INFO;

// SPRING_INFO: hold data for a spring with dampers
typedef struct {
  long  ModelNum;
  VEC Offset;
  REAL  Length;
  REAL  Stiffness;
  REAL  Damping;
  REAL  Restitution;
} SPRING_INFO;

// Wheel Stuff
typedef struct {

  unsigned long Status; // Status flags

  REAL  Mass, InvMass;
  REAL  Inertia, InvInertia;
  REAL  Radius;
  REAL  Gravity;

  REAL  Grip;
  REAL  StaticFriction;
  REAL  KineticFriction;

  REAL  SteerRatio;   // To get turn angle from car's steering wheel angle
  REAL  EngineRatio;  // To get the torque from the engine voltage
  REAL  AxleFriction; // Guess

  BBOX  BBox;     // Bounding box
  REAL  BBRadius;   // Bounding sphere radius

  REAL  Pos;      // Position relative to axle
  REAL  AngPos;     // Rotational angle of the wheel 0 < AngPos < 2 PI
  REAL  Vel;      // Velocity along suspension axis (car's up vector)
  REAL  AngVel;     // Rotational Velocity
  REAL  Acc;      // Linear acceleration along axis
  REAL  AngAcc;     // Rotational acceleration
  REAL  Impulse;    // Linear impulse along axis
  REAL  AngImpulse;   // Rotational impulse

  REAL  MaxPos;     // Maximum offset allowed for wheels
  REAL  MaxAngVel;    // To reduce torque

  REAL  SpinAngImp;   // Angular impulse applied to wheel when it is spinning

  MAT WMatrix;    // World matrix
  VEC WPos;     // World position of fix point
  VEC OldWPos;
  VEC CentrePos;    // World position of wheel centre
  VEC OldCentrePos; 
  MAT Axes;     // 

  MAT EyeMatrix;    // 
  VEC EyeTrans;   //

  REAL  TurnAngle;    // Angle of wheel in car's look-right plane

  SKIDMARK_START  Skid; // Skid mark creation data
  REAL  SkidWidth;    // Max width of the skid mark

  REAL  OilTime;    // Time that wheel has been in oil

} WHEEL;

#define WHEEL_PRESENT (1)
#define WHEEL_STEERED (2)
#define WHEEL_POWERED (4)
#define WHEEL_CONTACT (8)
#define WHEEL_SPIN    (16)
#define WHEEL_SLIDE   (32)
#define WHEEL_LOCKED  (64)
#define WHEEL_OIL   (128)
#define WHEEL_SKID    (WHEEL_SPIN | WHEEL_SLIDE)


#define IsWheelPresent(wheel) ((wheel)->Status & WHEEL_PRESENT)
#define IsWheelTurnable(wheel) ((wheel)->Status & WHEEL_STEERED)
#define IsWheelPowered(wheel) ((wheel)->Status & WHEEL_POWERED)
#define IsWheelInContact(wheel) ((wheel)->Status & WHEEL_CONTACT)
#define IsWheelSpinning(wheel) ((wheel)->Status & WHEEL_SPIN)
#define IsWheelSliding(wheel) ((wheel)->Status & WHEEL_SLIDE)
#define IsWheelSkidding(wheel) ((wheel)->Status & WHEEL_SKID)
#define IsWheelLocked(wheel) ((wheel)->Status & WHEEL_LOCKED)
#define IsWheelinOil(wheel) ((wheel)->Status & WHEEL_OIL)
#define SetWheelPresent(wheel) {(wheel)->Status |= WHEEL_PRESENT;}
#define SetWheelTurnable(wheel) {(wheel)->Status |= WHEEL_STEERED;}
#define SetWheelPowered(wheel) {(wheel)->Status |= WHEEL_POWERED;}
#define SetWheelInContact(wheel) {(wheel)->Status |= WHEEL_CONTACT;}
#define SetWheelSpinning(wheel) {(wheel)->Status |= WHEEL_SPIN;}
#define SetWheelSliding(wheel) {(wheel)->Status |= WHEEL_SLIDE;}
#define SetWheelLocked(wheel) {(wheel)->Status |= WHEEL_LOCKED;}
#define SetWheelInOil(wheel) {(wheel)->Status |= WHEEL_OIL;}
#define SetWheelNotPresent(wheel) {(wheel)->Status &= ~WHEEL_PRESENT;}
#define SetWheelNotTurnable(wheel) {(wheel)->Status &= ~WHEEL_STEERED;}
#define SetWheelNotPowered(wheel) {(wheel)->Status &= ~WHEEL_POWERED;}
#define SetWheelNotInContact(wheel) {(wheel)->Status &= ~WHEEL_CONTACT;}
#define SetWheelNotSpinning(wheel) {(wheel)->Status &= ~WHEEL_SPIN;}
#define SetWheelNotSliding(wheel) {(wheel)->Status &= ~WHEEL_SLIDE;}
#define SetWheelNotLocked(wheel) {(wheel)->Status &= ~WHEEL_LOCKED;}
#define SetWheelNotInOil(wheel) {(wheel)->Status &= ~WHEEL_OIL;}

#define SetWheelStatus(wheel, present, steered, powered) \
{(wheel)->Status |= ((present) | (steered) | (powered));}


extern void SetupWheel(WHEEL *wheel, WHEEL_INFO *wheelInfo); 
extern void SetupSuspension(SPRING *spring, SPRING_INFO *info);
extern REAL SpringDampedForce(SPRING *spring, REAL extension, REAL velocity);

extern SKIDMARK *AddSkid(SKIDMARK_START *skidStart, SKIDMARK_START *skidEnd, long rgb);
extern void MoveSkidEnd(SKIDMARK *skid, SKIDMARK_START *skidEnd);
extern void ClearSkids();
extern void FadeSkidMarks();

extern int WHL_NSkids;
extern int WHL_SkidHead;
extern SKIDMARK WHL_SkidMark[SKID_MAX_SKIDS];


#endif

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