Processing 1

void setup()
{
  size(800, 600);
}

void flaga(int x, int y, int szer, int wys)
{
  for (int i=x; i <szer; i++)
  {
    for (int j = y; j < wys/3; j++)
    {
      color c = color(0, 0, 0);
      set(i, j, c);
    }
  }
 for (int i=x; i <szer; i++)
 {
   for (int j= wys/3; j < 2*wys/3-y; j++)
   {
     color c = color(255, 0, 0);
     set(i, j, c);
   }
 }
 for (int i=x; i <szer; i++)
 {
   for (int j= 2*wys/3-y; j < wys-2*y; j++)
   {
     color c = color(255, 255, 0);
     set(i, j, c);
   }
 }
}

void putPixel(int x, int y, int r, int g, int b)
{
  r &=255;
  g &=255;
  b &=255;
  int a =y + width * x;
  int k=255000000 | (r<<16) | (g<<8) | (b) ;
  pixels[a] = k;
}

void draw()
{
//flaga (10, 50, 500, 400);
loadPixels();
putPixel(10, 10, 255, 0, 0);
}