Shield.cpp

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/*  Project Starshatter 5.0
        Destroyer Studios LLC
        Copyright © 1997-2007. All Rights Reserved.

        SUBSYSTEM:    Stars.exe
        FILE:         Shield.cpp
        AUTHOR:       John DiCamillo


        OVERVIEW
        ========
        Weapon class
*/

#include "MemDebug.h"
#include "Shield.h"
#include "Shot.h"
#include "WeaponDesign.h"

#include "Game.h"

// +----------------------------------------------------------------------+

static char*   shield_name[] = {
        "sys.shield.none",
        "sys.shield.deflector",
        "sys.shield.grav",
        "sys.shield.hyper"
};

static int     shield_value[] = {
        0, 2, 2, 3
};

// +----------------------------------------------------------------------+

Shield::Shield(SUBTYPE shield_type)
: System(SHIELD, shield_type, "shield", shield_value[shield_type], 100, 0),
shield_cutoff(0.0f), shield_capacitor(false), shield_bubble(false),
deflection_cost(1.0f), shield_curve(0.05f)
{
        name = Game::GetText(shield_name[shield_type]);
        abrv = Game::GetText("sys.shield.abrv");

        power_flags  = POWER_WATTS | POWER_CRITICAL;
        energy       = 0.0f;
        power_level  = 0.0f;
        shield_level = 0.0f;

        switch (shield_type) {
        default:
        case DEFLECTOR:
                capacity = sink_rate = 2.0e3f;
                shield_factor        = 0.05f;
                break;

        case GRAV_SHIELD:
                capacity = sink_rate = 7.0e3f;
                shield_factor        = 0.01f;
                break;

        case HYPER_SHIELD:
                capacity = sink_rate = 10.0e3f;
                shield_factor        = 0.003f;
                break;
        }

        emcon_power[0] = 0;
        emcon_power[1] = 0;
        emcon_power[2] = 100;
}

// +----------------------------------------------------------------------+

Shield::Shield(const Shield& s)
: System(s), shield_factor(s.shield_factor), requested_power_level(0.0f),
shield_cutoff(s.shield_cutoff), shield_capacitor(s.shield_capacitor),
shield_bubble(s.shield_bubble), deflection_cost(s.deflection_cost),
shield_curve(s.shield_curve)
{
        power_flags  = s.power_flags;
        energy       = 0.0f;
        power_level  = 0.0f;
        shield_level = 0.0f;

        Mount(s);
}

// +--------------------------------------------------------------------+

Shield::~Shield()
{ }

void
Shield::SetShieldCapacitor(bool c)
{
        shield_capacitor = c;

        if (shield_capacitor) {
                power_flags = POWER_CRITICAL;
                shield_curve = 0.05f;
        }
        else {
                power_flags = POWER_WATTS | POWER_CRITICAL;
                shield_curve = 0.25f;
        }
}

// +--------------------------------------------------------------------+

void
Shield::ExecFrame(double seconds)
{
        System::ExecFrame(seconds);

        if (power_level < requested_power_level) {
                power_level += (float) (seconds * 0.10);     // ten seconds to charge up

                if (power_level > requested_power_level)
                power_level = (float) requested_power_level;
        }
        else if (power_level > requested_power_level) {
                power_level -= (float) (seconds * 0.20);     // five seconds to power down

                if (power_level < requested_power_level)
                power_level = (float) requested_power_level;
        }

        if (power_level < 0.01 && !shield_capacitor) {
                shield_level = 0.0f;
                energy       = 0.0f;
        }
}

// +----------------------------------------------------------------------+

void
Shield::Distribute(double delivered_energy, double seconds)
{
        System::Distribute(delivered_energy, seconds);

        if (shield_capacitor) {
                if (shield_cutoff > 0 && shield_cutoff < 0.999) {
                        float cutoff = shield_cutoff * capacity;

                        if (energy > cutoff)
                        shield_level = (energy-cutoff)/(capacity-cutoff);
                        else
                        shield_level = 0.0f;
                }

                else {
                        shield_level = energy/capacity;
                }
        }
        else {
                shield_level = energy/sink_rate;
                energy       = 0.0f;
        }

        if (shield_level < 0)
        shield_level = 0;
}

// +--------------------------------------------------------------------+

double
Shield::DeflectDamage(Shot* shot, double damage)
{
        double filter      = 1;
        double penetration = 5;
        double leak        = 0;

        if (shot)
        penetration = shot->Design()->penetration;

        filter = 1 - shield_factor * penetration;

        if (filter < 0)
        filter = 0;

        else if (filter > 1)
        filter = 1;

        if (shield_capacitor) {
                if (shield_cutoff > 0 && shield_level < 1e-6) {
                        leak = damage;
                        energy -= (float) (damage * deflection_cost);
                }

                else {
                        leak = damage * (1 - pow(shield_level, shield_curve) * filter * availability);

                        double deflected = damage - leak;
                        energy -= (float) deflected * deflection_cost;
                }

        }
        else {
                leak = damage * (1 - pow(shield_level, shield_curve) * filter * availability);
        }

        return leak;
}

// +--------------------------------------------------------------------+

void
Shield::SetPowerLevel(double level)
{
        if (level > 100)
        level = 100;
        else if (level < 0)
        level = 0;

        level /= 100;

        if (requested_power_level != level) {
                // if the system is on emergency override power,
                // do not let the EMCON system use this method
                // to drop it back to normal power:
                if (power_level > 1 && level == 1) {
                        requested_power_level = (float) power_level;
                        return;
                }

                requested_power_level = (float) level;
        }
}

void
Shield::SetNetShieldLevel(int level)
{
        if (level > 100)     level = 100;
        else if (level < 0)  level =   0;

        requested_power_level = (float) (level/100.0);
        power_level           = requested_power_level;
}

void
Shield::DoEMCON(int index)
{
        int e = GetEMCONPower(index);

        if (power_level * 100 > e || emcon != index) {
                if (e == 0) {
                        PowerOff();
                }
                else if (emcon != index) {
                        PowerOn();

                        if (power_level * 100 > e)
                        SetPowerLevel(e);
                }
        }

        emcon = index;
}