#include <Arduino.h>
#include <U8g2lib.h> // u8g2 library is used to draw graphics on the OLED display
#include <Wire.h> // library required for IIC communication

//Docs:  https://github.com/olikraus/u8g2/wiki/u8g2reference#drawbox

U8G2_SSD1306_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE); // initialization for the 128x64px OLED display

const int potPin = A0; // analog pin for potentiometer
int heading = 100; // predefined heading marker at 100 degrees

void setup() {
  u8g2.begin();
}

void loop() {
  int sensorValue = analogRead(potPin);
  int degrees = map(sensorValue, 0, 1023, 0, 360);

  u8g2.clearBuffer(); // clear the internal memory
  u8g2.setFont(u8g2_font_ncenB08_tr); // choose a suitable font
  u8g2.setCursor(50, 10);
  u8g2.print(degrees);
  //u8g2.print(" '");

  u8g2.drawLine(0, 15, 128, 15); // horizontal line for compass ticks

  // Draw compass ticks and heading marker
  for (int i = -90; i <= 90; i += 10) {
    int angle = degrees + i;
    if (angle < 0) angle += 360;
    if (angle >= 360) angle -= 360;

    int x = map(i, -90, 90, 0, 128);

    if (angle == heading) {
      //Syntex: u8g2.drawBox(x,y,w,h);
      u8g2.drawBox(x - 1, 20, 5, 5); // draw heading marker (small filled square)
    } else {
      //u8g2.drawLine(x, 15, x, 15);
      u8g2.drawPixel(x, 31); // draw compass tick
    }

//So if(i%30==0) means if i is divided by 30 and the remainder is equals 
//to 0 then the statement is true else it is false.
    if (i % 30 == 0) { // draw degree labels every 30 degrees
      u8g2.setCursor(x - 6, 45);
      u8g2.print(angle);
    }
  }

  u8g2.sendBuffer(); // transfer internal memory to the display
  delay(20); // add a small delay to avoid flickering
}