// PROGRAM rc
// 交流電圧源の接続された RC 回路のシミュレーション

#include "TrueBASIC.h"
#include "csgraphics.h"

#define V(V0,omega,t) ((V0)*cos((omega)*(t)))

int main();
void initial(double *Q, double *R, double *tau, double *V0, double *omega, 
             double *tmax, double *t, double *dt);
void set_up_windows(int IC1_, int IC2_, double V0, double tmax);
void scope(double *Q, double *I, double R, double tau, double V0, double omega, 
           double t, double dt);
void source_voltage(int IC1_, double V0, double omega, double t);
void output_voltage(int IC2_, double I, double R, double t);

int main()
{
    int IC1_ = 1, IC2_ = 2;
    double I, Q, R, V0, dt, omega, t, tau, tmax;

    GWopen(0);

    initial(&Q, &R, &tau, &V0, &omega, &tmax, &t, &dt);
    set_up_windows(IC1_, IC2_, V0, tmax);
    source_voltage(IC1_, V0, omega, t);
    output_voltage(IC2_, I, R, t);
    while(t <= tmax)
    {
        scope(&Q, &I, R, tau, V0, omega, t, dt);
        t += dt;
        source_voltage(IC1_, V0, omega, t);
        output_voltage(IC2_, I, R, t);
    }

    GWquit();
    return 0;
}

void initial(double *Q, double *R, double *tau, double *V0, double *omega, 
             double *tmax, double *t, double *dt)
{
    double C, f, period;
    char Stmp1_[_LBUFF_];

    (*t) = 0;
    (*V0) = 1;                              // 外部電圧の振幅
    printf("external voltage frequency (Hertz) = ");
    fgets(Stmp1_, _LBUFF_, stdin);
    sscanf(Stmp1_, "%lg", &f);
    (*omega) = 2*pi*f;                      // 角振動数
    printf("resistance (ohms) = ");
    fgets(Stmp1_, _LBUFF_, stdin);
    sscanf(Stmp1_, "%lg", R);
    printf("capacitance (farads) = ");
    fgets(Stmp1_, _LBUFF_, stdin);
    sscanf(Stmp1_, "%lg", &C);
    printf("time step dt = ");
    fgets(Stmp1_, _LBUFF_, stdin);
    sscanf(Stmp1_, "%lg", dt);
    (*Q) = 0;
    (*tau) = (*R)*C;                        // 緩和時間
    period = 1/f;                           // 外部振動数の周期
    if(period > (*tau))
        (*tmax) = 2*period;
    else
        (*tmax) = 2*(*tau);
}

void set_up_windows(int IC1_, int IC2_, double V0, double tmax)
{
    double Vmin, tmin;

    GWvport(0.0f, 0.0f, GWaspect(1), 0.5f);
    tmin = 0;
    Vmin = -V0;
    draw_axes((float)tmin, (float)tmax, (float)Vmin, (float)V0);
    GWputtxt((float)tmin, (float)(V0), "source voltage");
    GWsavevp(IC1_);
    GWvport(0.0f, 0.5f, GWaspect(1), 1.0f);
    draw_axes((float)tmin, (float)tmax, (float)Vmin, (float)V0);
    GWputtxt((float)tmin, (float)(V0), "voltage drop across resistor");
    GWsavevp(IC2_);
}

void scope(double *Q, double *I, double R, double tau, double V0, double omega, 
           double t, double dt)
{
    // 電圧降下の計算
    (*I) = V(V0, omega, t)/R - (*Q)/tau;
    (*Q) += (*I)*dt;
}

void source_voltage(int IC1_, double V0, double omega, double t)
{
    static float x = -100.0f, y = -100.0f;
    GWselvp(IC1_);
    GWsetpen(BLUE, -1, -1, -1);
    GWmove2(x, y);
    x = (float)(t);
    y = (float)(V(V0, omega, t));
    GWline2(x, y);
}

void output_voltage(int IC2_, double I, double R, double t)
// 抵抗器の電圧降下
{
    static float x = -100.0f, y = -100.0f;
    GWselvp(IC2_);
    GWsetpen(RED, -1, -1, -1);
    GWmove2(x, y);
    x = (float)(t);
    y = (float)(I*R);
    GWline2(x, y);
}