mpri-graphics-project/periodic_updates.cpp

#include "periodic_updates.hpp"

#include <ctime>
#include <chrono>
#include <GL/glut.h>

static Ball* _ball = nullptr;
static std::chrono::time_point<std::chrono::steady_clock>
    _last_time, _init_clocks;

static bool is_paused = false;
static double speed_factor = 1.;

void init_periodic_static(Ball* ball) {
    _last_time = std::chrono::steady_clock::now();
    _init_clocks = std::chrono::steady_clock::now();
    _ball = ball;
}

double ellapsed_double(
        std::chrono::time_point<std::chrono::steady_clock> beg,
        std::chrono::time_point<std::chrono::steady_clock> end)
{
    std::chrono::duration<double> ellapsed_db = end - beg;
    return ellapsed_db.count();
}

void periodic_update() {
    if(is_paused)
        return;

    printf("%lf\n", speed_factor);
    auto now = std::chrono::steady_clock::now();
    _ball->update_pos(speed_factor * ellapsed_double(_last_time, now));

    _last_time = now;
    glutPostRedisplay();
}

void periodic_kb_handler(unsigned char key, int, int) {
    if(key == ' ') {
        if(is_paused)
            _last_time = std::chrono::steady_clock::now();
        is_paused = !is_paused;
    }
    else if(key == '<') {
        speed_factor -= .1;
        if(speed_factor <= 0.05)
            speed_factor = .1;
    }
    else if(key == '>') {
        speed_factor += .1;
    }
    else if(key == '0') {
        speed_factor = 1.;
    }
}