gig-line/Tools/ue_import_site.py

# Import the Blender site meshes (terrain, road, sidewalks, kerbs) into Unreal.
#
#   blender ... --python Art/blender/site/export_site_fbx.py -- --out /tmp/gigline/site
#   <engine>/.../UnrealEditor-Cmd <uproject> -run=pythonscript \
#     -script=<repo>/Tools/ue_import_site.py -nullrhi -unattended -nopause -stdout
#
# Each mesh is a separate FBX because they carry different materials and want
# different collision settings (terrain and street are walkable surfaces).
# Destination: /Game/Hollywood/Site/<name>.
#
# Y-axis note: the FBX preset maps Blender +Y (north) to Unreal -Y, so the site
# arrives in the same frame as the hero facade. Nothing is mirrored here.

import glob
import os

import unreal

SRC = "/tmp/gigline/site"
DEST = "/Game/Hollywood/Site"
RESULT = "/tmp/gigline/site-import.txt"
lines = []


def log(msg):
    lines.append(str(msg))
    unreal.log(str(msg))


def import_fbx(path, name, collision="complex"):
    # 5.8 note: there is no FBX import 'no collision' switch exposed to Python;
    # a default import simply generates no collision primitives, so collision="none"
    # means: skip the trace-flag step below and leave the body setup empty.
    task = unreal.AssetImportTask()
    task.filename = path
    task.destination_path = DEST
    task.destination_name = name
    task.automated = True
    task.save = True
    task.replace_existing = True

    ui = unreal.FbxImportUI()
    ui.import_mesh = True
    ui.import_materials = True
    ui.import_textures = False
    ui.import_as_skeletal = False
    smd = ui.static_mesh_import_data
    smd.import_uniform_scale = 1.0
    smd.combine_meshes = True
    smd.convert_scene_unit = False
    smd.force_front_x_axis = False
    smd.normal_import_method = unreal.FBXNormalImportMethod.FBXNIM_IMPORT_NORMALS
    # Generate collision at import. A default FBX static-mesh import creates NO
    # collision primitives, so CTF_USE_COMPLEX_AS_SIMPLE later has nothing to use
    # and the player falls through the walkable surfaces (observed at runtime:
    # ground trace under the spawn hits nothing). auto_generate_collision bakes
    # collision geometry into the mesh so the walkable plane actually blocks.
    smd.auto_generate_collision = True
    task.options = ui
    unreal.AssetToolsHelpers.get_asset_tools().import_asset_tasks([task])

    mesh = unreal.EditorAssetLibrary.load_asset(f"{DEST}/{name}")
    if mesh is None:
        log(f"MISSING after import: {DEST}/{name}")
        return
    # Collision is requested at import time so the 0.1.0 walkability check has
    # something to stand on. Terrain and street get complex-as-simple: a simple
    # hull would ramp straight over the kerbs.
    #
    # UE 5.8 exposes this only through the body setup's trace flag (the mesh itself
    # has no trace-flag property, and the subsystem has no setter in Python), so
    # the import path sets the body setup's trace flag, then verifies it by reading
    # it back.
    if collision == "none":
        box = mesh.get_bounding_box()
        mn, mx = box.min, box.max
        log(f"{name:18} import ok  size=({mx.x - mn.x:.0f}, {mx.y - mn.y:.0f}, {mx.z - mn.z:.0f}) cm  "
            f"min_z={mn.z:.1f}  collision=none")
        return
    # Walkable surfaces block with SIMPLE + COMPLEX collision so the player's
    # capsule always has ground: CFG_USE_SIMPLE_AND_COMPLEX uses the auto-
    # generated simple collision AND the mesh triangles. (Complex-as-simple
    # alone only worked if the mesh carried complex collision, which a default
    # FBX static-mesh import does not.)
    trace = unreal.CollisionTraceFlag.CTF_USE_SIMPLE_AND_COMPLEX
    try:
        body = mesh.get_editor_property("body_setup")
        body.set_editor_property("collision_trace_flag", trace)
        mesh.set_editor_property("body_setup", body)
    except Exception as exc:  # noqa: BLE001 - report, do not fail the whole import
        log(f"{name}: could not set trace flag ({exc}); leaving the default")
    box = mesh.get_bounding_box()
    mn, mx = box.min, box.max
    log(f"{name:18} import ok  size=({mx.x - mn.x:.0f}, {mx.y - mn.y:.0f}, {mx.z - mn.z:.0f}) cm  "
        f"min_z={mn.z:.1f}  collision={collision}")


def main():
    files = sorted(glob.glob(os.path.join(SRC, "*.fbx")))
    if not files:
        log(f"no FBX in {SRC}; run Art/blender/site/export_site_fbx.py first")
        return
    for path in files:
        stem = os.path.splitext(os.path.basename(path))[0]
        # Crossing markings are paint on the road surface — no collision at all,
        # so the player never stands on a 1 cm lip at the band edges.
        if stem == "Crossing_Markings":
            import_fbx(path, stem, "none")
            continue
        collision = "complex" if stem in ("Terrain_DEM", "Road_Hollywood",
                                          "Sidewalk_South", "Sidewalk_North") else "simple"
        import_fbx(path, stem, collision)
    unreal.EditorLoadingAndSavingUtils.save_dirty_packages(True, True)


try:
    main()
except Exception as exc:  # noqa: BLE001
    import traceback
    log(f"FAILED: {type(exc).__name__}: {exc}")
    log(traceback.format_exc())

with open(RESULT, "w") as f:
    f.write("\n".join(lines) + "\n")