# Spur Gear 24T
# A 24-tooth, module 2.5 spur gear (60 mm pitch diameter) with a 6.4 mm bore and 12 mm hub.
#
# Generated by 3DBlend — https://github.com/alfredang/3dblend
# Run in Blender 3.6+ : Scripting workspace > Open > Run Script (Alt+P)
# Units are millimetres (scene unit scale is set to 0.001).
# The object is left on the build plate (min Z = 0, centred on origin) and is
# ready for File > Export > STL.

import bpy, bmesh
from math import radians, cos, sin, pi
from mathutils import Matrix, Vector, Euler

def _reset_scene():
    bpy.ops.object.select_all(action='SELECT')
    bpy.ops.object.delete(use_global=False)
    scn = bpy.context.scene
    scn.unit_settings.system = 'METRIC'
    scn.unit_settings.scale_length = 0.001
    scn.unit_settings.length_unit = 'MILLIMETERS'

_reset_scene()

def _apply_all(o):
    bpy.context.view_layer.objects.active = o
    o.select_set(True)
    for m in list(o.modifiers):
        bpy.ops.object.modifier_apply(modifier=m.name)
    o.select_set(False)
    return o

def _obj_from_bmesh(bm, name):
    me = bpy.data.meshes.new(name)
    bm.to_mesh(me); bm.free()
    o = bpy.data.objects.new(name, me)
    bpy.context.collection.objects.link(o)
    return o

def add_cube(size, loc):
    bm = bmesh.new()
    bmesh.ops.create_cube(bm, size=1.0)
    bmesh.ops.scale(bm, vec=Vector(size), verts=bm.verts)
    bmesh.ops.translate(bm, vec=Vector(loc), verts=bm.verts)
    return _obj_from_bmesh(bm, "Cube")

def add_cone(r1, r2, depth, segs, loc):
    bm = bmesh.new()
    bmesh.ops.create_cone(bm, cap_ends=True, cap_tris=False, segments=int(segs), radius1=r1, radius2=max(r2, 1e-6), depth=depth)
    bmesh.ops.translate(bm, vec=Vector(loc), verts=bm.verts)
    return _obj_from_bmesh(bm, "Cylinder")

def add_sphere(r, segs):
    bm = bmesh.new()
    bmesh.ops.create_uvsphere(bm, u_segments=int(segs), v_segments=max(8, int(segs/2)), radius=r)
    return _obj_from_bmesh(bm, "Sphere")

def add_torus(R, r, segs):
    bpy.ops.mesh.primitive_torus_add(major_radius=R, minor_radius=r, major_segments=int(segs), minor_segments=max(12, int(segs/2)))
    o = bpy.context.active_object
    o.select_set(False)
    return o

def add_rounded_box(size, radius, loc):
    o = add_cube(size, loc)
    bev = o.modifiers.new("Bevel", 'BEVEL')
    bev.width = min(radius, min(size)/2 - 1e-3)
    bev.segments = 8
    bev.limit_method = 'NONE'
    return _apply_all(o)

def _polygon_bmesh(poly):
    bm = bmesh.new()
    verts = [bm.verts.new((x, y, 0.0)) for (x, y) in poly]
    bm.faces.new(verts)
    bm.normal_update()
    return bm, verts

def add_extrude(poly, height, twist, scale_top, center):
    bm, verts = _polygon_bmesh(poly)
    face = bm.faces[0]
    if face.normal.z < 0:
        bmesh.ops.reverse_faces(bm, faces=[face])
    res = bmesh.ops.extrude_face_region(bm, geom=[face])
    top_verts = [g for g in res['geom'] if isinstance(g, bmesh.types.BMVert)]
    bmesh.ops.translate(bm, vec=Vector((0, 0, height)), verts=top_verts)
    if scale_top != (1, 1) or twist:
        m = Matrix.Diagonal((scale_top[0], scale_top[1], 1.0, 1.0)) @ Matrix.Rotation(radians(twist), 4, 'Z')
        bmesh.ops.transform(bm, matrix=m, verts=top_verts)
    if center:
        bmesh.ops.translate(bm, vec=Vector((0, 0, -height/2)), verts=bm.verts)
    bmesh.ops.recalc_face_normals(bm, faces=bm.faces)
    return _obj_from_bmesh(bm, "Extrude")

def add_revolve(poly, degrees, segs):
    bm = bmesh.new()
    verts = [bm.verts.new((max(0.0, x), 0.0, y)) for (x, y) in poly]
    edges = [bm.edges.new((verts[i], verts[(i+1) % len(verts)])) for i in range(len(verts))]
    bmesh.ops.spin(bm, geom=verts + edges, cent=(0,0,0), axis=(0,0,1), angle=radians(degrees), steps=int(segs), use_merge=(degrees >= 360))
    bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=1e-4)
    if degrees < 360:
        bmesh.ops.holes_fill(bm, edges=bm.edges)
    bmesh.ops.recalc_face_normals(bm, faces=bm.faces)
    return _obj_from_bmesh(bm, "Revolve")

def boolean(a, b, op):
    mod = a.modifiers.new(op.title(), 'BOOLEAN')
    mod.operation = op
    mod.solver = 'EXACT'
    mod.object = b
    _apply_all(a)
    bpy.data.objects.remove(b, do_unlink=True)
    return a

def union_all(objs):
    base = objs[0]
    for o in objs[1:]:
        base = boolean(base, o, 'UNION')
    return base

def convex_hull(o):
    bm = bmesh.new(); bm.from_mesh(o.data)
    bmesh.ops.convex_hull(bm, input=bm.verts)
    bmesh.ops.delete(bm, geom=[v for v in bm.verts if not v.link_faces], context='VERTS')
    bm.to_mesh(o.data); bm.free()
    return o

def transform(o, matrix):
    o.data.transform(matrix)
    o.data.update()
    return o

def mirror(o, normal):
    n = Vector(normal).normalized()
    m = Matrix.Identity(4)
    for i in range(3):
        for j in range(3):
            m[i][j] = (1.0 if i == j else 0.0) - 2.0 * n[i] * n[j]
    transform(o, m)
    bm = bmesh.new(); bm.from_mesh(o.data)
    bmesh.ops.reverse_faces(bm, faces=bm.faces)
    bm.to_mesh(o.data); bm.free()
    return o

def _copy(o):
    c = o.copy(); c.data = o.data.copy()
    bpy.context.collection.objects.link(c)
    return c

def linear_array(o, count, step):
    copies = []
    for i in range(1, int(count)):
        c = _copy(o)
        transform(c, Matrix.Translation(Vector(step) * i))
        copies.append(c)
    return union_all([o] + copies)

def radial_array(o, count, radius, degrees):
    if radius:
        transform(o, Matrix.Translation((radius, 0, 0)))
    step = (360.0 / count) if degrees >= 360 else (degrees / (count - 1) if count > 1 else 0)
    copies = []
    for i in range(1, int(count)):
        c = _copy(o)
        transform(c, Matrix.Rotation(radians(step * i), 4, 'Z'))
        copies.append(c)
    return union_all([o] + copies)

def finish(o):
    # Seat on the build plate: centre XY, min Z = 0.
    xs = [v.co.x for v in o.data.vertices]; ys = [v.co.y for v in o.data.vertices]; zs = [v.co.z for v in o.data.vertices]
    cx = (min(xs) + max(xs)) / 2; cy = (min(ys) + max(ys)) / 2
    transform(o, Matrix.Translation((-cx, -cy, -min(zs))))
    bm = bmesh.new(); bm.from_mesh(o.data)
    bmesh.ops.remove_doubles(bm, verts=bm.verts, dist=1e-4)
    bmesh.ops.recalc_face_normals(bm, faces=bm.faces)
    bm.to_mesh(o.data); bm.free()
    bpy.context.view_layer.objects.active = o
    o.select_set(True)

# ---------------------------------------------------------------- model
cyl_1 = add_cone(28.5, 28.5, 10, 96, (0, 0, 5))
extrude_2 = add_extrude(((0,-3.6),(4.5,-1.8),(5.5,-1),(5.5,1),(4.5,1.8),(0,3.6)), 10, 0, (1,1), False)
transform(extrude_2, Matrix.Translation((28,0,0)))
extrude_2.name = "tooth"
radial_3 = radial_array(extrude_2, 24, 0, 360)
cyl_4 = add_cone(12, 12, 16, 64, (0, 0, 8))
union_5 = union_all([cyl_1, radial_3, cyl_4])
cyl_6 = add_cone(3.2, 3.2, 20, 64, (0, 0, 10))
transform(cyl_6, Matrix.Translation((0,0,-1)))
cyl_7 = add_cone(4, 4, 12, 64, (0, 0, 6))
transform(cyl_7, Matrix.Translation((0,0,-1)))
radial_8 = radial_array(cyl_7, 6, 19, 360)
diff_9 = boolean(union_5, union_all([cyl_6, radial_8]), 'DIFFERENCE')
root = diff_9
root.name = "Spur Gear 24T"
finish(root)