#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>

U8G2_SH1106_128X64_NONAME_1_HW_I2C U8G2(U8G2_R0, 5, 4, U8X8_PIN_NONE);

int values[120];                                            // array for sine values
int buffer[120];                                            // buffer array used to shift sine values

void initArrays(void){
// fill arrays
for (int i = 0; i < 120; i++){
    float angle = i * 3;                                    // 3 * 120 = 360
    values[i] = (32 + (sin(angle * (M_PI / 180)) * 30));    // values shifted upwards by 32 for easier visualization
    buffer[i] = values[i];                                  // initialize buffer with the same values
  }
}

void setup(void) {
  U8G2.begin();                                             // initialize and clear display
  initArrays();                                             // initialize arrays
}

void loop(void) {
// constantly repeating code
  U8G2.firstPage();
  do {
    U8G2.drawVLine(0, 0, 64);                               // draw Y-axis
    U8G2.drawHLine(0, 63, 128);                             // draw X-axis

    for (int j = 0 ; j < 120; j++){
      values[j] = buffer[j];                                // transfer values from buffer to output array
      U8G2.drawPixel(j+4, values[j]);                       // draw the sine wave with values from the array shifted 4 pixels to the right
    }

    for (int x = 0 ; x < 120; x++){                         // loop array via buffer
      if(x-1 < 0){
        buffer[x] = values[119];
      } else {
      buffer[x] = values[x-1];
      }
    }
  }
  while ( U8G2.nextPage() );
  delay(50);                                                // control scroll speed of the sine wave
}