Generate wall library.py

1. !/usr/bin/env python3

from pathlib import Path import sys import yaml import FreeCAD import Part

OUTPUT_DIR = Path("cad_library")

IN = 25.4

def load_yaml(path):

   with open(path, "r") as f:
       return yaml.safe_load(f)

def nominal_to_actual_lumber(nominal):

   table = {
       "2x2": (1.5, 1.5),
       "2x3": (1.5, 2.5),
       "2x4": (1.5, 3.5),
       "2x6": (1.5, 5.5),
       "2x8": (1.5, 7.25),
       "2x10": (1.5, 9.25),
       "2x12": (1.5, 11.25),
   }

   return table[nominal]

def in_to_mm(v):

   return v * IN

def ft_to_in(v):

   return v * 12

def derive_stud_positions(width_in, stud_thickness_in, spacing_oc_in):

   positions = [0.0]

   right_edge = width_in - stud_thickness_in
   current = spacing_oc_in

   while current + stud_thickness_in <= right_edge:
       positions.append(current)
       current += spacing_oc_in

   if positions[-1] != right_edge:
       positions.append(right_edge)

   return positions

def build_wall(instance):

   instance_id = instance["id"]
   params = instance["parameters"]

   width_ft = params["nominal_width_ft"]
   height_ft = params["nominal_height_ft"]
   stud_nominal = params["stud_lumber_nominal"]
   spacing_oc_in = params["stud_spacing_oc_in"]
   osb_thickness_in = params["osb_thickness_in"]

   stud_thickness_in, stud_depth_in = nominal_to_actual_lumber(stud_nominal)

   width_in = ft_to_in(width_ft)
   framed_height_in = ft_to_in(height_ft)

   plate_thickness_in = stud_thickness_in
   stud_length_in = framed_height_in - (2 * plate_thickness_in)

   width_mm = in_to_mm(width_in)
   stud_depth_mm = in_to_mm(stud_depth_in)
   plate_thickness_mm = in_to_mm(plate_thickness_in)
   stud_length_mm = in_to_mm(stud_length_in)
   osb_thickness_mm = in_to_mm(osb_thickness_in)
   framed_height_mm = in_to_mm(framed_height_in)

   shapes = []

   # bottom plate
   shapes.append(
       Part.makeBox(
           width_mm,
           stud_depth_mm,
           plate_thickness_mm
       )
   )

   # top plate
   top_plate = Part.makeBox(
       width_mm,
       stud_depth_mm,
       plate_thickness_mm
   )

   top_plate.translate(
       FreeCAD.Vector(
           0,
           0,
           framed_height_mm - plate_thickness_mm
       )
   )

   shapes.append(top_plate)

   # studs
   stud_positions = derive_stud_positions(width_in, stud_thickness_in, spacing_oc_in)

   for x in stud_positions:

       stud = Part.makeBox(
           in_to_mm(stud_thickness_in),
           stud_depth_mm,
           stud_length_mm
       )

       stud.translate(
           FreeCAD.Vector(
               in_to_mm(x),
               0,
               plate_thickness_mm
           )
       )

       shapes.append(stud)

   # OSB sheathing (south side = negative Y)
   osb = Part.makeBox(
       width_mm,
       osb_thickness_mm,
       framed_height_mm
   )

   osb.translate(
       FreeCAD.Vector(
           0,
           -osb_thickness_mm,
           0
       )
   )

   shapes.append(osb)

   # create compound module
   wall = Part.makeCompound(shapes)

   doc = FreeCAD.newDocument(instance_id)

   obj = doc.addObject("Part::Feature", "wall_module")

   obj.Shape = wall

   doc.recompute()

   return doc

def save_document(doc, path):

   path.parent.mkdir(exist_ok=True)

   doc.saveAs(str(path))

def main():

   if len(sys.argv) != 2:
       print("Usage: generate_wall_library.py instances.yaml")
       sys.exit(1)

   instances_doc = load_yaml(sys.argv[1])

   instances = instances_doc["instances"]

   OUTPUT_DIR.mkdir(exist_ok=True)

   for inst in instances:

       instance_id = inst["id"]

       print(f"Generating {instance_id}...")

       doc = build_wall(inst)

       out_path = OUTPUT_DIR / f"{instance_id}.FCStd"

       save_document(doc, out_path)

       print(f"Saved {out_path}")

   print(f"Generated {len(instances)} modules")

if __name__ == "__main__":

   main()