int x = 0;
int y = 0;

void setup()
{
size(500,500);
}

void draw()
{

int rect_width = int(random(100));
fill(int(random(255)),int(random(255)),int(random(255)));
rect(x,y,rect_width,100);
x = x + rect_width;

if (x > 500) {
  
y = y+15;
x = 0;
}
}