pilot_heat.c

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/*
 * See Licensing and Copyright notice in naev.h
 */

#include <math.h>
 
#include "naev.h"
 
#include "pilot_heat.h"
 
#include "array.h"
 
/*
 * Prototypes.
 */
static double pilot_heatOutfitMod( const Pilot *p, const Outfit *o );

void pilot_heatCalc( Pilot *p )
{
   double mass_kg;
   mass_kg      = 1000. * p->base_mass;
   p->heat_emis = 0.8; 
   p->heat_cond = STEEL_HEAT_CONDUCTIVITY;
   p->heat_C    = STEEL_HEAT_CAPACITY * mass_kg;
 
   /* We'll approximate area for a sphere.
    *
    * Sphere:
    *  V = 4/3*pi*r^3
    *  A = 4*pi*r^2
    *
    * Ship:
    *  V = mass/density
    *
    * We then equal the ship V and sphere V to obtain r:
    *  r = (3*mass)/(4*pi*density))^(1/3)
    *
    * Substituting r in A we get:
    *  A = 4*pi*((3*mass)/(4*pi*density))^(2/3)
    * */
   p->heat_area = 4. * M_PI *
                  pow( 3. / 4. * mass_kg / STEEL_DENSITY / M_PI, 2. / 3. ) *
                  p->stats.heat_dissipation;
}

double pilot_heatCalcOutfitC( const Outfit *o )
{
   /* Simple thermal mass. Put a floor on it so we get zero heat flux in case of
    * NaN for massless outfits. */
   return STEEL_HEAT_CAPACITY * MAX( 1000. * o->mass, 1. );
}

double pilot_heatCalcOutfitArea( const Outfit *o )
{
   double mass_kg = MAX( 1000. * o->mass, 1. ); /* Avoid it being 0. */
   /* We consider the effective area of outfits to be half of a sphere. */
   return 2. * M_PI * pow( 3. / 4. * mass_kg / STEEL_DENSITY / M_PI, 2. / 3. );
}

void pilot_heatCalcSlot( PilotOutfitSlot *o )
{
   o->heat_T     = CONST_SPACE_STAR_TEMP; /* Reset temperature. */
   o->heat_start = CONST_SPACE_STAR_TEMP; /* For cooldown purposes. */
   if ( o->outfit == NULL ) {
      o->heat_C    = 1.;
      o->heat_area = 0.;
      return;
   }
   o->heat_C    = pilot_heatCalcOutfitC( o->outfit );
   o->heat_area = pilot_heatCalcOutfitArea( o->outfit );
}

void pilot_heatReset( Pilot *p )
{
   p->heat_T = CONST_SPACE_STAR_TEMP;
   for ( int i = 0; i < array_size( p->outfits ); i++ )
      p->outfits[i]->heat_T = CONST_SPACE_STAR_TEMP;
}

static double pilot_heatOutfitMod( const Pilot *p, const Outfit *o )
{
   switch ( o->type ) {
   case OUTFIT_TYPE_BOLT:
   case OUTFIT_TYPE_BEAM:
      return p->stats.fwd_heat;
 
   case OUTFIT_TYPE_TURRET_BOLT:
   case OUTFIT_TYPE_TURRET_BEAM:
      return p->stats.tur_heat;
 
   default:
      return 1.;
   }
}

void pilot_heatAddSlot( const Pilot *p, PilotOutfitSlot *o )
{
   /* We consider that only 1% of the energy is lost in the form of heat,
    * this keeps numbers safe. */
   double hmod = pilot_heatOutfitMod( p, o->outfit );
 
   o->heat_T += hmod * outfit_heat( o->outfit ) / o->heat_C;
 
   /* Enforce a minimum value as a safety measure. */
   o->heat_T = MAX( o->heat_T, CONST_SPACE_STAR_TEMP );
}

void pilot_heatAddSlotTime( const Pilot *p, PilotOutfitSlot *o, double dt )
{
   double hmod = pilot_heatOutfitMod( p, o->outfit );
 
   o->heat_T += ( hmod * outfit_heat( o->outfit ) / o->heat_C ) * dt;
 
   /* Enforce a minimum value as a safety measure. */
   o->heat_T = MAX( o->heat_T, CONST_SPACE_STAR_TEMP );
}

double pilot_heatUpdateSlot( const Pilot *p, PilotOutfitSlot *o, double dt )
{
   /* Calculate energy leaving/entering ship chassis. */
   double Q = -p->heat_cond * ( o->heat_T - p->heat_T ) * o->heat_area * dt;
 
   /* Update current temperature. */
   o->heat_T += Q / o->heat_C;
 
   /* Return energy moved. */
   return Q;
}

void pilot_heatUpdateShip( Pilot *p, double Q_cond, double dt )
{
   double Q, Q_rad;
 
   /* Calculate radiation. */
   Q_rad = CONST_STEFAN_BOLTZMANN * p->heat_area * p->heat_emis *
           ( CONST_SPACE_STAR_TEMP_4 - pow( p->heat_T, 4. ) ) * dt;
 
   /* Total heat movement. */
   Q = Q_rad - Q_cond;
 
   /* Update ship temperature. */
   p->heat_T += Q / p->heat_C;
}

double pilot_heatEfficiencyMod( double T, double Tb, double Tc )
{
   return CLAMP( 0., 1., 1. - ( T - Tb ) / Tc );
}

void pilot_heatUpdateCooldown( Pilot *p )
{
   double t  = pow2( 1. - p->ctimer / p->cdelay );
   p->heat_T = p->heat_start - CONST_SPACE_STAR_TEMP -
               ( p->heat_start - CONST_SPACE_STAR_TEMP ) * t +
               CONST_SPACE_STAR_TEMP;
 
   for ( int i = 0; i < array_size( p->outfits ); i++ ) {
      int              ammo_threshold;
      PilotOutfitSlot *o = p->outfits[i];
      o->heat_T          = o->heat_start - CONST_SPACE_STAR_TEMP -
                  ( o->heat_start - CONST_SPACE_STAR_TEMP ) * t +
                  CONST_SPACE_STAR_TEMP;
 
      /* Refill ammo too (also part of Active Cooldown) */
      /* Must be valid outfit. */
      if ( o->outfit == NULL )
         continue;
 
      /* Initial (raw) ammo threshold */
      ammo_threshold = round( t * pilot_maxAmmoO( p, o->outfit ) );
 
      /* Adjust for deployed fighters if needed */
      if ( outfit_isFighterBay( o->outfit ) )
         ammo_threshold -= o->u.ammo.deployed;
 
      if ( o->u.ammo.quantity < ammo_threshold )
         pilot_addAmmo( p, p->outfits[i], ammo_threshold - o->u.ammo.quantity );
   }
}

double pilot_heatAccuracyMod( double T )
{
   return CLAMP( 0., 1., ( T - 500. ) / 600. );
}

double pilot_heatFireRateMod( double T )
{
   return CLAMP( 0., 1., ( 1100. - T ) / 300. );
}

double pilot_heatFirePercent( double T )
{
   return 2. * pilot_heatAccuracyMod( T );
}