Generating a random office building

[RoKr93]

I'm trying to write a program that generates a randomized city scene (with respect to the color/height/width/placement of the buildings in it) and am currently focusing on generating one office building with random height, width, color, and number of windows.

I'm having a spot of trouble figuring out how to constrain my number of rows/columns of windows to fit nicely within the office building. This seems like some relatively simple math that I'm just not wrapping my head around, but if there's a cleaner way to do this programming-wise I'd welcome suggestions about that as well.

Here's my code so far:

#include "library.h"

void one_window(int x, int y, int width, int height)
{
	fill_rectangle(x,y,width,height);
}
void row_windows(int x, int y, int width, int height, int n)
{
	one_window(x,y,width,height);
	if(n>1)
	{
		row_windows(x+(1.5*width),y,width,height,n-1);
	}
}
void block_windows(int x, int y, int width, int height, int n, int floors)
{
	row_windows(x,y,width,height,n);
	if(floors>1)
	{
		block_windows(x,y+(1.5*height),width,height,n,floors-1);
	}
}
void office_building(int x, int y, int width, int height, int n, int floors)
{
	double R = (random_in_range(0,30))/100.0;
	double G = (random_in_range(0,30))/100.0;
	double B = (random_in_range(0,30))/100.0;
	set_pen_color(R,G,B);
	fill_rectangle(x,y,width,height);
	double Gw = (random_in_range(10,25))/100.0;
	double Bw = (random_in_range(10,25))/100.0;
	set_pen_color(0,Gw,Bw);
	block_windows(x+(n),y+(floors),((width/n)-n),((height/floors)-floors),n,floors);
}
void main()
{
	int width = random_in_range(100,300);
	int height = random_in_range(100,300);
	int n = random_in_range(4,6);
	int floors = random_in_range(5,20);
	make_window(600,600);
	office_building(100,200,width,height,n,floors);
}

Thanks!