Multiple loop problem dealing with boolean subtraction

Hi, all,

I'm trying to do multiple loops in hoopsnake to generate a pattern. The process has the following steps:

1. Define a boundary B_0 with a closed polyline.

2. Randomly put some rectangles R_1 into the boundary B_0.

3. Define a new boundary B_1 and compute the region C_1 = R_1 - B_1 (boolean operation); save C_1 for the next iteration.

4. Repeat Steps 2 and 3. In each iteration, C_i = C_(i-1) - B_i, in which B_i is a new boundary.

Now I managed to iterate step 2, and I have trouble putting step 3 into the iteration. Could anyone help me out?

I have two hoopsnake components. The one on the right does step 2. When it finishes, it triggers the one on the left, which generates a new boundary. At this moment, I feed the new boundary to another iteration (step 2), but I should add a boolean subtraction here and somehow pass the boolean result to the next iteration (please see diagram 3 and 4). I cannot figure where to do this boolean and how to pass it on.

I have my files here. Please take a look. Thank you for your time!