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"
#include "log.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);
}