settled-reach/tooling/blender_process_hair.py

"""
blender_process_hair.py
Usage: tooling/blender --background --python tooling/blender_process_hair.py -- <source_base_dir> <hair_out_dir> <facial_hair_out_dir> <eyebrows_out_dir>

Converts Quaternius Source tier hairstyle GLTF files (rigged to Head bone) into
production GLBs with mask PNG sidecars.

Source base dir: .../Hairstyles/Rigged to Head Bone/glTF (Godot -Unreal)/

Output:
  hair/           {key}.glb + {key}_mask.png      (hair styles)
  facial_hair/    {key}.glb + {key}_mask.png      (beard, moustache, mutton_chops)
  eyebrows/       {key}.glb                        (no mask — used as-is, tinted by shader)

Naming conventions from architecture doc (D-164):
  Quaternius name       -> file key
  Hair_Bob              -> bob
  Hair_Buns             -> buns
  Hair_BuzzedFemale     -> buzzed_female
  Hair_Long             -> long
  Hair_LongDreads       -> long_dreads
  Hair_Ponytail_2       -> ponytail_f
  Hair_Balding          -> balding
  Hair_Buzzed           -> buzzed
  Hair_Dreads           -> dreads
  Hair_Mohawk           -> mohawk
  Hair_Ponytail         -> ponytail
  Hair_SimpleParted     -> simple_parted
  Hair_SlickBack        -> slick_back
  Hair_Beard            -> beard         [facial_hair/]
  Hair_Moustache        -> moustache     [facial_hair/]
  Hair_MuttonChops      -> mutton_chops  [facial_hair/]
  Eyebrows_Female       -> female        [eyebrows/]
  Eyebrows_Regular      -> regular       [eyebrows/]
  Eyebrows_Teen         -> teen          [eyebrows/]
  Eyebrows_Thick        -> thick         [eyebrows/]

Also produces bald.glb (minimal empty mesh placeholder for 'no hair' slot).
"""

import sys
import os
import bpy

# (source_gltf_relative_to_base, output_key, output_dir_tag)
# dir_tag: "hair", "facial_hair", "eyebrows"
HAIR_MANIFEST = [
    # --- Female hairstyles ---
    ("Female/Hair_Bob.gltf",           "bob",            "hair"),
    ("Female/Hair_Buns.gltf",          "buns",           "hair"),
    ("Female/Hair_BuzzedFemale.gltf",  "buzzed_female",  "hair"),
    ("Female/Hair_Long.gltf",          "long",           "hair"),
    ("Female/Hair_LongDreads.gltf",    "long_dreads",    "hair"),
    ("Female/Hair_Ponytail_2.gltf",    "ponytail_f",     "hair"),
    # --- Male hairstyles ---
    ("Male/Hair_Balding.gltf",         "balding",        "hair"),
    ("Male/Hair_Buzzed.gltf",          "buzzed",         "hair"),
    ("Male/Hair_Dreads.gltf",          "dreads",         "hair"),
    ("Male/Hair_Mohawk.gltf",          "mohawk",         "hair"),
    ("Male/Hair_Ponytail.gltf",        "ponytail",       "hair"),
    ("Male/Hair_SimpleParted.gltf",    "simple_parted",  "hair"),
    ("Male/Hair_SlickBack.gltf",       "slick_back",     "hair"),
    # --- Facial hair ---
    ("Male/Hair_Beard.gltf",           "beard",          "facial_hair"),
    ("Male/Hair_Moustache.gltf",       "moustache",      "facial_hair"),
    ("Male/Hair_MuttonChops.gltf",     "mutton_chops",   "facial_hair"),
    # --- Eyebrows ---
    ("Female/Eyebrows_Female.gltf",    "female",         "eyebrows"),
    ("Female/Eyebrows_Teen.gltf",      "teen",           "eyebrows"),
    ("Male/Eyebrows_Regular.gltf",     "regular",        "eyebrows"),
    ("Male/Eyebrows_Thick.gltf",       "thick",          "eyebrows"),
]


def convert_gltf_to_glb(gltf_path: str, glb_path: str, solidify: bool = False) -> None:
    """Import a GLTF file and re-export as GLB with embedded textures."""
    bpy.ops.wm.read_factory_settings(use_empty=True)

    print(f"  Loading: {os.path.basename(gltf_path)}")
    bpy.ops.import_scene.gltf(filepath=gltf_path)

    objects = list(bpy.context.scene.objects)
    meshes  = [o for o in objects if o.type == 'MESH']
    arms    = [o for o in objects if o.type == 'ARMATURE']
    print(f"  Objects: {len(meshes)} meshes, {len(arms)} armatures")

    # Strip animation data (hair has no runtime animation)
    for obj in objects:
        if obj.animation_data:
            obj.animation_data_clear()
    for action in list(bpy.data.actions):
        bpy.data.actions.remove(action)

    # Solidify hair meshes — gives flat hair cards 3D thickness so they don't
    # clip through the scalp. Makes hair look like a hair-shaped shell.
    # Only applied to scalp hair, not eyebrows or facial hair.
    HAIR_THICKNESS = 0.020  # 20mm outward thickness
    if solidify:
        for m in meshes:
            # Skip icospheres and non-hair utility objects
            if m.name.startswith("Icosphere") or len(m.data.vertices) < 50:
                continue
            bpy.context.view_layer.objects.active = m
            m.select_set(True)
            # Recalculate normals to ensure consistent outward direction
            bpy.ops.object.mode_set(mode='EDIT')
            bpy.ops.mesh.select_all(action='SELECT')
            bpy.ops.mesh.normals_make_consistent(inside=False)
            bpy.ops.object.mode_set(mode='OBJECT')
            # Apply solidify
            sol_mod = m.modifiers.new(name="Solidify", type='SOLIDIFY')
            sol_mod.thickness = HAIR_THICKNESS
            sol_mod.offset = 1.0  # grow outward only
            sol_mod.use_rim = True  # fill edges for closed shell
            bpy.ops.object.modifier_apply(modifier=sol_mod.name)
            m.select_set(False)
            print(f"  Solidified: {m.name} ({HAIR_THICKNESS*1000:.0f}mm outward)")

    # Keep armature parenting and skin data intact — the Godot compositor
    # will load the skinned mesh and add it to the shared skeleton at runtime.
    bpy.ops.object.select_all(action='SELECT')

    bpy.ops.export_scene.gltf(
        filepath=glb_path,
        use_selection=True,
        export_format='GLB',
        export_animations=False,
        export_yup=True,
        export_image_format='AUTO',
        export_texcoords=True,
        export_normals=True,
        export_skins=True,
        export_materials='EXPORT',
    )
    size = os.path.getsize(glb_path)
    print(f"  GLB exported: {os.path.basename(glb_path)} ({size:,} bytes)")


def make_mask_png(mask_path: str, width: int = 64, height: int = 64) -> None:
    """Generate a solid-white mask PNG (entire mesh = tintable region).

    Solid white = fully tintable. Small size is fine — the shader just samples
    white everywhere. The mask format supports greyscale bands for multi-region
    recoloring when needed in future.
    """
    import struct
    import zlib

    # Build a minimal white PNG manually — no Blender image API issues
    def make_png(w, h):
        def chunk(ctype, data):
            c = ctype + data
            return struct.pack('>I', len(data)) + c + struct.pack('>I', zlib.crc32(c) & 0xffffffff)
        header = b'\x89PNG\r\n\x1a\n'
        ihdr = chunk(b'IHDR', struct.pack('>IIBBBBB', w, h, 8, 0, 0, 0, 0))  # 8-bit greyscale
        raw = b''
        for _ in range(h):
            raw += b'\x00' + b'\xff' * w  # filter byte + white pixels
        idat = chunk(b'IDAT', zlib.compress(raw))
        iend = chunk(b'IEND', b'')
        return header + ihdr + idat + iend

    with open(mask_path, 'wb') as f:
        f.write(make_png(width, height))
    print(f"  Mask saved: {os.path.basename(mask_path)} ({width}x{height} white)")


def make_bald_placeholder(glb_path: str) -> None:
    """Create a minimal empty GLB for the 'no hair' slot."""
    bpy.ops.wm.read_factory_settings(use_empty=True)
    # Create a single-vertex mesh with no faces (zero-poly placeholder)
    mesh_data = bpy.data.meshes.new("bald")
    mesh_data.from_pydata([(0.0, 0.0, 0.0)], [], [])
    mesh_data.update()
    obj = bpy.data.objects.new("bald", mesh_data)
    bpy.context.collection.objects.link(obj)
    bpy.ops.object.select_all(action='SELECT')
    bpy.ops.export_scene.gltf(
        filepath=glb_path,
        use_selection=True,
        export_format='GLB',
        export_animations=False,
        export_yup=True,
        export_image_format='AUTO',
        export_materials='EXPORT',
    )
    size = os.path.getsize(glb_path)
    print(f"  bald.glb placeholder ({size:,} bytes)")


if __name__ == "__main__":
    argv = sys.argv
    if "--" not in argv:
        print("Usage: tooling/blender --background --python tooling/blender_process_hair.py -- <source_base_dir> <hair_out_dir> <facial_hair_out_dir> <eyebrows_out_dir>")
        sys.exit(1)

    args = argv[argv.index("--") + 1:]
    if len(args) < 4:
        print("ERROR: Provide source_base_dir, hair_out_dir, facial_hair_out_dir, eyebrows_out_dir")
        sys.exit(1)

    source_base   = args[0]
    hair_out      = args[1]
    fhair_out     = args[2]
    eyebrows_out  = args[3]

    out_dirs = {"hair": hair_out, "facial_hair": fhair_out, "eyebrows": eyebrows_out}
    for d in out_dirs.values():
        os.makedirs(d, exist_ok=True)

    results = []
    errors  = []

    for (gltf_rel, key, tag) in HAIR_MANIFEST:
        gltf_path = os.path.join(source_base, gltf_rel)
        out_dir   = out_dirs[tag]

        if not os.path.exists(gltf_path):
            errors.append(f"  MISSING: {gltf_path}")
            continue

        print(f"\n[{tag}] {key}")
        glb_path = os.path.join(out_dir, key + ".glb")
        # Only solidify scalp hair — not facial hair or eyebrows
        convert_gltf_to_glb(gltf_path, glb_path, solidify=(tag == "hair"))

        # Eyebrows: no mask (tinted directly by shader, no recolor mask needed)
        if tag != "eyebrows":
            mask_path = os.path.join(out_dir, key + "_mask.png")
            make_mask_png(mask_path)

        results.append((tag, key, os.path.getsize(glb_path)))

    # bald.glb placeholder
    print("\n[hair] bald (placeholder)")
    bald_path = os.path.join(hair_out, "bald.glb")
    make_bald_placeholder(bald_path)
    results.append(("hair", "bald", os.path.getsize(bald_path)))

    print("\n=== Hairstyle import complete ===")
    for tag, key, size in results:
        print(f"  [{tag}] {key}.glb ({size:,} bytes)")

    if errors:
        print("\nMISSING FILES:")
        for e in errors:
            print(e)
        sys.exit(1)