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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

int x = 10;
int y = 32;
int radius = 8;

int speedX = 2;

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
}

void loop() {

  // clear previous frame
  display.clearDisplay();

  // draw circle
  display.drawCircle(x, y, radius, SSD1306_WHITE);

  // show frame
  display.display();

  // move circle
  x = x + speedX;

  // bounce on right edge
  if (x + radius >= 127) {
    speedX = -speedX;
  }

  // bounce on left edge
  if (x - radius <= 0) {
    speedX = -speedX;
  }

  delay(30);
}