#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

double radius = 27, x, y, endx = 128, centerx = endx / 2, endy = 64, centery = endy / 2;

void setup() {
  Serial.begin(115200);

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.display();

  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);

  display.drawPixel(centerx, centery, SSD1306_WHITE);
  display.drawRect(0, 0, endx, endy, SSD1306_WHITE);
}

void loop() {
  for (float i = 0; i < PI * 2; i += .05) {
    x = radius * cos(i);
    y = radius * sin(i);

    // draw buffer (with white)
    display.drawPixel(x + centerx, y + centery, SSD1306_WHITE);
    // display.setTextColor(SSD1306_WHITE);
    // display.setCursor(x + centerx, y + centery);
    // display.print("o");

    // display buffer
    display.display();

    // erase buffer (with black)
    display.drawPixel(x + centerx, y + centery, SSD1306_BLACK);
    // display.setTextColor(SSD1306_BLACK);
    // display.setCursor(x + centerx, y + centery);
    // display.print("o");
  }
}