Trig_Blog_Sample_3

#include <math.h>
#include <cstdio>
#include <unistd.h>

int main()
{
    struct ship
    {
        float x_pos;
        float y_pos;
        float x_dest;
        float y_dest;
        float spd;
    };

    ship my_ship;
    my_ship.spd = 10.0f;
    my_ship.x_pos = 0.0f;
    my_ship.y_pos = 0.0f;
    my_ship.x_dest = 2000.0f;
    my_ship.y_dest = 1500.0f;

    float x_dist = my_ship.x_dest - my_ship.x_pos;
    float y_dist = my_ship.y_dest - my_ship.y_pos;

    float angle = atan2f(y_dist, x_dist); // The differences in this and the following two lines.
    float x_ratio = cosf(angle);
    float y_ratio = sinf(angle);
    float x_spd_comp = my_ship.spd * x_ratio;
    float y_spd_comp = my_ship.spd * y_ratio;

    printf("Ship X_dest = %.2f,  Ship Y_dest = %.2f\n\n", my_ship.x_dest, my_ship.y_dest);

    while((my_ship.x_pos < (my_ship.x_dest - (my_ship.spd / 2.0f))) ||
          (my_ship.x_pos > (my_ship.x_dest + (my_ship.spd / 2.0f))) ||
          (my_ship.y_pos < (my_ship.y_dest - (my_ship.spd / 2.0f))) ||
          (my_ship.y_pos > (my_ship.y_dest + (my_ship.spd / 2.0f))))
    {
        my_ship.x_pos += x_spd_comp;
        my_ship.y_pos += y_spd_comp;
        printf("Ship X Pos = %.2f,  Ship Y Pos = %.2f\n", my_ship.x_pos, my_ship.y_pos);
        usleep(75000);
    }
    return 0;
}