1st tile for floor generator question

Hello community,
please check my definition. I want to make some floor generator (like 3ds max flugin) connected with Archicad. It work fine but I don’t know hot to fix some bugs.
Tiles generator_QA.gh (26.4 KB)
As you can see I have starting point and starting tile:

The problem is:
starting tile located outside the base surface. I want to have starting tile inside the base surface.
Consequently generator start from seam. Not from tile

if I understand your question correctly…

yes… thanks