Display simple graphics on OLED using ESP8266 NodeMCU.

ESP8266-NodeMCU-OLED-Graphics.ino

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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

#define OLED_MOSI   13
#define OLED_CLK   14
#define OLED_DC    5
#define OLED_CS    15
#define OLED_RESET 4
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT,
  OLED_MOSI, OLED_CLK, OLED_DC, OLED_RESET, OLED_CS);

void setup()
{
  Serial.begin(115200);
  if(!display.begin(SSD1306_SWITCHCAPVCC))
  {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  display.clearDisplay();
  display.display();
  delay(100);
}

void loop()
{
  DrawRectangle();
  DrawFilledRectangle();
  DrawRoundRectangle();
  DrawFilledRoundRectangle();
  DrawCircle();
  DrawFilledCircle();
  DrawTriangle();
  DrawFilledTriangle();
}


void DrawRectangle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.println("Rectangle");
  display.drawRect(0, 15, 90, 45, SSD1306_WHITE);
  display.display();
  delay(2000);
}

void DrawFilledRectangle()
{
  display.clearDisplay();  
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.println("Filled Rectangle");
  display.fillRect(0, 15, 90, 45, SSD1306_WHITE);
  display.display();
  delay(2000);
  
}

void DrawRoundRectangle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Round Rectangle");
  display.drawRoundRect(0, 15, 90, 45, 10, SSD1306_WHITE);
  display.display();
  delay(5000);
}

void DrawFilledRoundRectangle()
{
  display.clearDisplay();  
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Filled Round Rect");
  display.fillRoundRect(0, 15, 90, 45, 10, SSD1306_WHITE);
  display.display();
  delay(2000);
  
}

void DrawCircle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Circle");
  display.drawCircle(30, 36, 25, SSD1306_WHITE);
  display.display();
  delay(2000);
}
void DrawFilledCircle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Filled Circle");
  display.fillCircle(30, 36, 25, SSD1306_WHITE);
  display.display();
  delay(2000);
  
}

void DrawTriangle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Triangle");
  display.drawTriangle(30, 15, 0, 60, 60, 60, SSD1306_WHITE);
  display.display();
  delay(2000);  
}

void DrawFilledTriangle()
{
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0,0);
  display.println("Filled Triangle");
  display.fillTriangle(30, 15, 0, 60, 60, 60, SSD1306_WHITE);
  display.display();
  delay(2000);
}