mpri-graphics-project/periodic_updates.cpp

#include "periodic_updates.hpp"

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

struct Movement {
    Movement()  :
        fwd(false),
        bck(false),
        left(false),
        right(false),
        turn_l(false),
        turn_r(false),
        sight_angle(3.14159)
    {}

    bool
        fwd,
        bck,
        left,
        right,
        turn_l,
        turn_r;

    double sight_angle;

    void tick() {
        sight_angle += (turn_l - turn_r) * .05;
    }

    Point movement() {
        Point front_dir = Point(-sin(sight_angle), 0, -cos(sight_angle)),
              left_dir = Point(-cos(sight_angle), 0, sin(sight_angle));
        return (fwd - bck) * front_dir
            + (left - right) * left_dir;
    }
    Point sight() {
        return Point(-sin(sight_angle), 0., -cos(sight_angle));
    }
};

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.;
static KeyMappings _keymap = KeyMappings::qwerty();
static Movement _movement;
static Point _position(0., 2.5, -10.);
static GlutRender* _render = nullptr;

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

void set_key_mapping(const KeyMappings& mapping) {
    _keymap = mapping;
}

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() {
    auto now = std::chrono::steady_clock::now();

    if(!is_paused)
        _ball->update_pos(speed_factor * ellapsed_double(_last_time, now));

    _movement.tick();
    _position += _movement.movement();
    Point look_at = _position + _movement.sight();

    _render->set_camera(_position, look_at);

    _last_time = now;
    glutPostRedisplay();
}

void mvt_keys_update(bool up, unsigned key) {
    if(key == _keymap.mv_fwd)
        _movement.fwd = !up;
    else if(key == _keymap.mv_bck)
        _movement.bck = !up;
    else if(key == _keymap.mv_left)
        _movement.left = !up;
    else if(key == _keymap.mv_right)
        _movement.right = !up;
    else if(key == _keymap.turn_left)
        _movement.turn_l = !up;
    else if(key == _keymap.turn_right)
        _movement.turn_r = !up;
}

void periodic_kb_handler(unsigned char key, int, int) {
    if(key == ' ')
        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.;
    }
    mvt_keys_update(false, key);
}

void periodic_kb_up_handler(unsigned char key, int, int) {
    mvt_keys_update(true, key);
}