script.js

//main script


const frame_rate = 1000 / 60;
var frame_number = 0;
var first_frame_date = Date.now();
var current_frame_rate = 0;

var language = "en";

const sound = true;
var context = new AudioContext();

const first_car_index = 2;

var air_resistance = true;
var rolling_resistance = true;
var angle = 0;



//functions for frequently needed calculations
var calculator = {
    speed_from_rpm: function(car, rpm) {
        var smooth_shift_progress = Math.sin(car.data.shift_progress / 2 * Math.PI);

        var wheel_rpm = rpm / (smooth_shift_progress * car.properties.gear_ratios[car.data.gear - 1]
                        + (1 - smooth_shift_progress) * car.properties.gear_ratios[car.data.previous_gear - 1])
                        / car.properties.final_drive;
        var wheel_rps = wheel_rpm / 60;
        var wheel_speed =  Math.PI * car.properties.tire_diameter * wheel_rps;

        return wheel_speed;
    },

    rpm_from_speed: function(car, speed) {
        var smooth_shift_progress = Math.sin(car.data.shift_progress / 2 * Math.PI);

        var wheel_rps = speed / (Math.PI * car.properties.tire_diameter);
        var wheel_rpm = wheel_rps * 60;
        var engine_rpm = wheel_rpm * car.properties.final_drive* (smooth_shift_progress
                         * car.properties.gear_ratios[car.data.gear - 1] + (1 - smooth_shift_progress)
                         * car.properties.gear_ratios[car.data.previous_gear - 1]);

        return engine_rpm;
    },

    wheel_torque: function(tcar) {
        var smooth_shift_progress = Math.sin(tcar.data.shift_progress / 2 * Math.PI);

        var temp_car = JSON.parse(JSON.stringify(tcar));
        temp_car.data.shift_progress = 1;
        temp_car.data.rpm = calculator.rpm_from_speed(temp_car, temp_car.data.speed);

        var engine_rpm_new = temp_car.data.rpm;
        var engine_rpm_old = temp_car.data.rpm * (car.properties.gear_ratios[car.data.previous_gear - 1]
                             / car.properties.gear_ratios[car.data.gear - 1]);

        var wheel_torque_new = car.engine_torque(engine_rpm_new, tcar.data.throttle)
                               * tcar.properties.gear_ratios[tcar.data.gear - 1] * car.properties.final_drive;
        var wheel_torque_old = car.engine_torque(engine_rpm_old, tcar.data.throttle)
                               * tcar.properties.gear_ratios[tcar.data.previous_gear - 1] * car.properties.final_drive;

        var wheel_torque = (1 - smooth_shift_progress) * wheel_torque_old + smooth_shift_progress * wheel_torque_new;

        return wheel_torque; 
    },

    wheel_force: function(tcar) {
        return calculator.wheel_torque(tcar) / (tcar.properties.tire_diameter / 2);
    },

    acceleration: function(tcar) {
        var car_accel = (calculator.wheel_force(tcar)) / tcar.properties.mass
                        - tcar.data.brake * tcar.properties.maximum_brake_deceleration;

        var angle_accel = -1 * Math.sin(angle * Math.PI/180) * 9.81;
        var air_accel = 0;
        var rolling_accel = 0;

        if (air_resistance === true) {
            air_accel = (-1 * 0.5 * 1.204 * (tcar.data.speed ** 2)
                        * tcar.properties.drag_coefficient * tcar.properties.frontal_area) / tcar.properties.mass;
        }

        if (rolling_resistance === true) {
            rolling_accel = -1 * (0.01 * Math.cos((angle * 2 * Math.PI) / 360) * tcar.properties.mass * 9.81)
                            / tcar.properties.mass;
        }

        return car_accel + angle_accel + air_accel + rolling_accel;
    }
};





//setup; execution after all files have been loaded
window.onload = function() {
    car.properties = car_data[first_car_index].properties;

	gauges.initialize();
    stopwatch.reset();

    if (sound === true) {
        car.sound.setup_sound();

        window.onclick = function() {
            context.resume();
        };
    }

	setInterval(main, frame_rate);
};



//main function; execution each frame
function main() {
    //get inputs
    car.data.throttle = parseInt(document.getElementById("throttle_input").value) / 100;
    car.data.brake = parseInt(document.getElementById("brake_input").value) / 100;
    angle = parseInt(document.getElementById("angle_input").value);
    air_resistance = document.getElementById("air_resistance_input").checked;
    rolling_resistance = document.getElementById("rolling_resistance_input").checked;


    //adjust shift progress
    if (car.data.shift_progress < 1) {
        car.data.shift_progress += (frame_rate / 1000) / car.properties.shift_time;
    }

    if (car.data.shift_progress > 1) {
        car.data.shift_progress = 1;
    }


    //increase throttle if the engine is below idle_rpm
    if (car.data.rpm <= car.properties.idle_rpm && car.data.throttle <= car.properties.idle_throttle) {
        car.data.throttle = car.properties.idle_throttle;
    }


    //set speed and engine rpm
    car.data.speed = car.data.speed + calculator.acceleration(car) * (frame_rate / 1000);

    if (car.data.speed < 0) {
        car.data.speed = 0;
    }

    car.data.rpm = calculator.rpm_from_speed(car, car.data.speed);

    if (car.data.rpm > car.properties.rpm_limiter) {
        car.data.rpm = car.properties.rpm_limiter;
        car.data.speed = calculator.speed_from_rpm(car, car.properties.rpm_limiter);
    }


    //automatic shifting
    var strategy_input_value = document.getElementById("strategy_select").value;

    switch (strategy_input_value) {
        case "r1":
            autoshift_strategy_5_1();
            break;
        case "r2":
            autoshift_strategy_5_2();
            break;
        case "r3":
            autoshift_strategy_5_3();
            break;
        case "g1":
            autoshift_strategy_4();
            break;
        case "a1":
            autoshift_strategy_3();
            break;
    }


    //sound
    if (sound === true) {
        car.sound.update_sound();
    }


    //visualize
	var street = document.getElementById("street");
	street_position_relative = parseFloat(street.style.left);

    var scale = parseFloat(getComputedStyle(document.documentElement).getPropertyValue('--scale'));

	street.style.left = (street_position_relative - car.data.speed * frame_rate / 1000 * scale) % (10 * scale) + "vw";
    document.getElementById("simulation_container").style.transform = `rotate(${-angle}deg)`;


    //update stopwatch
    if (stopwatch.running === true) {
        stopwatch.update();
    }


    //calculate frame rate
    if (frame_number >= 50) {
        let current_date = Date.now();
        current_frame_rate = 1000 / ((current_date - first_frame_date) / 50);
        first_frame_date = Date.now();
        frame_number = 0;
    }

    frame_number += 1;


    //print information
    document.getElementById("velocity_label").innerText = (car.data.speed * 3.6).toFixed(2);
    document.getElementById("engine_speed_label").innerText = car.data.rpm.toFixed(2);
    document.getElementById("gear_label").innerText = car.data.gear;
    document.getElementById("previous_gear_label").innerText = car.data.previous_gear;
    document.getElementById("shift_progress_label").innerText = parseInt(car.data.shift_progress * 100);
    document.getElementById("acceleration_label").innerText = (calculator.acceleration(car)).toFixed(2);
    document.getElementById("engine_torque_label").innerText = car.engine_torque().toFixed(2);
    document.getElementById("wheel_torque_label").innerText = calculator.wheel_torque(car).toFixed(2);
    document.getElementById("load_label").innerText = (car.data.throttle * 100).toFixed(0);
    document.getElementById("brake_label").innerText = (car.data.brake * 100).toFixed(0);
    document.getElementById("slope_label").innerText = (Math.tan(angle * (2 * Math.PI) / 360) * 100).toFixed(2);
    document.getElementById("frame_rate_label").innerText = current_frame_rate.toFixed(0);

    gauges.update();
}