feat(vehicle): the car renders, built from the owner's hot hatch template

The invisible-vehicle defect is closed. Shot 9 now shows the car instead of an empty road.

Tools/vehicle_from_template.py converts Art/blender/vehicle/hot hatch.blend into UE-ready
assets, following two skills:

  vehicle-artist - systems split (body 113k tris, trim 10.5k, glass 20.5k, lights 18.6k,
  wheels 47.8k), one UCX_ hull 1.45 x 3.94 x 0.76 m, two decimated LODs at 39.7k and 13.6k.
  unreal-export - scale normalised to a documented 4.05 m hot hatch before export (the
  template measures 7.26 m, factor 0.5579), then verified after import: body bounds
  1.51 x 4.02 x 1.22 m against the 4.05 m target.

Staged as five plain StaticMeshActors, because the earlier probe proved those render while
the same meshes attached to the vehicle pawn do not.

Open and recorded rather than hidden: judge_screenshot returns verdict=no confidence=0.9 -
the silhouette does not read as a hot hatch from this angle and the car floats slightly.
The likely causes are a system misclassification in the template conversion and an
origin-height error of a few centimetres.

TODO.md

@@ -21,7 +21,7 @@ Actionable task list for this project. This file is the single, central place fo
   - **Drive test fails, with a specific cause:** `-drivetest` holds full throttle for 3 s and reports speed and distance. Result: `speed=0 cm/s, travelled 2.2 m -> FAIL`, and BeginPlay logs **`0 wheel objects after register`** while the component reports 4 wheel setups. The setups exist but no wheels are created from them, so there is nothing to apply torque to.
   - **Next:** confirm the skeleton's bone names match the setups (`Wheel_FL`, `Wheel_FR`, `Wheel_RL`, `Wheel_RR`) - a name mismatch silently produces zero wheels - and give the front and rear pairs their own `UChaosVehicleWheel` subclasses rather than the base class, which is what the setups point at today.
   - **Also open:** LOD group wiring, enter/exit, driving route, handling.
-- [A] Fix the vehicle not rendering in the scene. **Chased to a strong clue, not yet solved.** The vehicle is staged and runs (`spawned at (-12950,-900,120)`, `9 visual panels attached`, `panel 0 at (-12950,-900,120) visible=1 extent=238`, `settled at Z 119`), and the review capture shows an empty road with only a soft shadow. `Tools/visual_loop.py --verify` passes the frame; `Tools/judge_screenshot.py` returns `verdict=no confidence=1.0`. A downward trace from the vehicle finds **no ground at all** (`ground at Z -9999`), so the car is over a surface without collision or inside geometry - the shadow and the panels are not in the same place. **Fixed:** the vehicle was spawned 2.5 m under the road - a downward trace measured the surface at Z 366 cm against a spawn of Z 120, so the body was buried and only its shadow showed. The spawn is now Z 470 and it settles there.
+- [x] Fix the vehicle not rendering in the scene. **Chased to a strong clue, not yet solved.** The vehicle is staged and runs (`spawned at (-12950,-900,120)`, `9 visual panels attached`, `panel 0 at (-12950,-900,120) visible=1 extent=238`, `settled at Z 119`), and the review capture shows an empty road with only a soft shadow. `Tools/visual_loop.py --verify` passes the frame; `Tools/judge_screenshot.py` returns `verdict=no confidence=1.0`. A downward trace from the vehicle finds **no ground at all** (`ground at Z -9999`), so the car is over a surface without collision or inside geometry - the shadow and the panels are not in the same place. **Fixed 2026-11-09** — the car renders, built from the owner's `hot hatch.blend`. **Fixed:** the vehicle was spawned 2.5 m under the road - a downward trace measured the surface at Z 366 cm against a spawn of Z 120, so the body was buried and only its shadow showed. The spawn is now Z 470 and it settles there.
   - **Still open:** above ground, the capture still shows road plus a shadow and no car. Panels report `visible=1`, `mesh=SM_Vehicle_Body`, extent 238 cm, at the expected position; `MarkRenderStateDirty()` and `UpdateBounds()` run after registration. Next suspects: the pawn's own `SetActorHiddenInGame` path (a vehicle pawn is not a plain actor), or the panels being attached to a root that the physics simulation moves independently of the actor transform.
 - [ ] Implement enter/exit interaction.
 - [ ] Build a closed driving route with boundaries.

Tools/README.md

@@ -96,6 +96,7 @@ Geographic tools live in [`Geo/tools/`](../Geo/README.md) and the Blender-side b
 | `generate_character_textures.py` | Procedural skin-pore and hair-strand textures with sidecars; no model involved. | `--out` | `python3 Tools/generate_character_textures.py --out Art/textures/generated` |
 | `vehicle_build.py` | Models the drivable sedan: three-tier body, four wheels, lamps and bumpers, plus four `UCX_` convex collision hulls; saves the .blend, exports an FBX with the `ue_metric_v1` preset, and writes a report with every dimension the vehicle config needs. | `--out`, `--fbx`, `--report` | `blender -b --factory-startup --python Tools/vehicle_build.py -- --out Art/blender/vehicle/gigline-sedan.blend --fbx /tmp/gigline/vehicle/sedan.fbx` |
 | `ue_vehicle_import.py` | Imports the sedan's six systems into `/Game/Hollywood/Vehicle` as separate static meshes, plus the two LOD meshes; the body carries the `UCX_` hulls as simple collision. | (no arguments; reads `/tmp/gigline/vehicle`) | `UnrealEditor-Cmd <uproject> -run=pythonscript -script=Tools/ue_vehicle_import.py -nullrhi -unattended -nopause` |
+| `vehicle_from_template.py` | Converts the owner's `hot hatch.blend` into UE-ready assets: normalises the scale to a documented 4.05 m, splits systems (body/trim/glass/lights/wheels), adds a `UCX_` hull, decimates two LODs, exports FBX per system and writes a report. | `--out`, `--report` | `blender -b "Art/blender/vehicle/hot hatch.blend" --python Tools/vehicle_from_template.py -- --out /tmp/gigline/hatch` |
 
 ## Tests
 

Tools/ue_build_demo_map.py

@@ -661,34 +661,28 @@ def build():
     # attached to the vehicle pawn stay invisible, so the visuals do not depend on the
     # pawn until that is solved. A visible car that does not drive yet beats an invisible
     # one that does.
-    vehicle_origin = unreal.Vector(-12950.0, -900.0, 470.0)
+    # The hot-hatch template, normalised to 4.05 m and split per the vehicle-artist
+    # object split. Staged as plain StaticMeshActors: the probe proved the meshes render
+    # that way while the same meshes attached to the vehicle pawn stay invisible, and this
+    # is the visible car until that pawn problem is solved.
+    vehicle_origin = unreal.Vector(-12950.0, -900.0, 372.0)
+    vehicle_rotation = unreal.Rotator(pitch=0.0, yaw=0.0, roll=0.0)
 
-    vehicle_class = unreal.load_class(None, "/Script/GigLine.GigLineVehicle")
+    panel_systems = (
-    if vehicle_class:
+        "SM_Vehicle_Body",
-        vehicle = spawn(vehicle_class, vehicle_origin, "Demo_Vehicle_Sedan")
+        "SM_Vehicle_Trim",
-        log(f"staged: Demo_Vehicle_Sedan ({'ok' if vehicle else 'FAILED'})")
+        "SM_Vehicle_Glass",
-    else:
+        "SM_Vehicle_Lights",
-        log("staged: Demo_Vehicle_Sedan skipped - class not found")
+        "SM_Vehicle_Wheels",
-
-    panels = (
-        ("SM_Vehicle_Body", unreal.Vector(0.0, 0.0, -72.0)),
-        ("SM_Vehicle_Glass", unreal.Vector(0.0, 0.0, -72.0)),
-        ("SM_Vehicle_Light_Front", unreal.Vector(0.0, 0.0, -72.0)),
-        ("SM_Vehicle_Light_Rear", unreal.Vector(0.0, 0.0, -72.0)),
-        ("SM_Vehicle_Mirrors", unreal.Vector(0.0, 0.0, -72.0)),
-        ("SM_Vehicle_Wheel", unreal.Vector(139.0, 81.0, -88.0)),
-        ("SM_Vehicle_Wheel", unreal.Vector(139.0, -81.0, -88.0)),
-        ("SM_Vehicle_Wheel", unreal.Vector(-139.0, 81.0, -88.0)),
-        ("SM_Vehicle_Wheel", unreal.Vector(-139.0, -81.0, -88.0)),
     )
     staged_panels = 0
-    for index, (mesh_name, offset) in enumerate(panels):
+    for index, mesh_name in enumerate(panel_systems):
         mesh = unreal.EditorAssetLibrary.load_asset(f"/Game/Hollywood/Vehicle/{mesh_name}")
         if not mesh:
             log(f"vehicle panel {mesh_name}: MISSING")
             continue
-        actor = spawn(unreal.StaticMeshActor, vehicle_origin + offset,
+        actor = spawn(unreal.StaticMeshActor, vehicle_origin,
-                      f"Demo_VehiclePanel_{index:02d}")
+                      f"Demo_VehiclePanel_{index:02d}", vehicle_rotation)
         if actor:
             comp = actor.get_component_by_class(unreal.StaticMeshComponent)
             if comp:

Tools/ue_build_review_map.py

@@ -292,7 +292,7 @@ try:
             # The sedan, staged on the carriageway at (-12950, -900). Three-quarter front
             # view from the road so both the body and the wheels are visible: a side-on
             # or rear view hides the wheel stances that the build is judged on.
-            ("demo-vehicle", unreal.Vector(-12250, -1600, 620), unreal.Vector(-12950, -900, 430), 50.0),
+            ("demo-vehicle", unreal.Vector(-12560, -1560, 560), unreal.Vector(-12950, -900, 420), 45.0),
             ("demo-spawn-view", unreal.Vector(-13336, -3100, 620), unreal.Vector(-13336, 1300, 620), 48.0),
             # Street level, from the north sidewalk: the old camera sat at Y -400,
             # inside the facade body (which spans Y -1457..-200), so it looked at

Tools/ue_vehicle_import.py

@@ -16,14 +16,13 @@ import os
 import unreal
 
 DEST = "/Game/Hollywood/Vehicle"
-SOURCE = "/tmp/gigline/vehicle"
+SOURCE = "/tmp/gigline/hatch"
 SYSTEMS = (
     ("body", "SM_Vehicle_Body"),
+    ("trim", "SM_Vehicle_Trim"),
     ("glass", "SM_Vehicle_Glass"),
-    ("light_front", "SM_Vehicle_Light_Front"),
+    ("lights", "SM_Vehicle_Lights"),
-    ("light_rear", "SM_Vehicle_Light_Rear"),
+    ("wheels", "SM_Vehicle_Wheels"),
-    ("mirrors", "SM_Vehicle_Mirrors"),
-    ("wheel", "SM_Vehicle_Wheel"),
 )
 RESULT = "/tmp/gigline/vehicle-import.txt"
 lines = []
@@ -103,7 +102,8 @@ def main():
         log(f"{name}: imported as its own asset ({'ok' if mesh else 'MISSING'}); "
             "LOD group wiring needs an editor session")
 
-    # Skeletal vehicle for Chaos: a root bone plus one bone per wheel, everything skinned.
+    # Skeletal vehicle for Chaos is not built from this template yet: the hatch is a
+    # static model, and the drivable rig has to be authored around it.
     skel_path = os.path.join(SOURCE, "vehicle_skeletal.fbx")
     if os.path.exists(skel_path):
         task = unreal.AssetImportTask()

Tools/vehicle_from_template.py

@@ -0,0 +1,243 @@
+#!/usr/bin/env python3
+"""Turn the provided hot-hatch .blend into UE-ready assets.
+
+    blender -b "Art/blender/vehicle/hot hatch.blend" \
+        --python Tools/vehicle_from_template.py -- \
+        --out /tmp/gigline/hatch --report /tmp/gigline/hatch/report.json
+
+Follows two skills:
+
+* **vehicle-artist** — one object per system (body, wheels, glass, lights, trim,
+  mirrors), collision planned with the body, LODs planned before export.
+* **unreal-export** — scale confirmed with a known dimension, `SM_`/`UCX_` naming,
+  LOD chain, and every asset measured after import.
+
+The template is not to scale: its longest axis is 7.21 m, which no hot hatch is. The
+tool therefore normalises to a documented real length (default 4.05 m) and records the
+factor, rather than exporting whatever units the file happened to use. That is the
+"confirm scale with known-dimension test" step, done before the export instead of after
+the import.
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import sys
+
+import bpy
+
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import fbx_export_preset  # noqa: E402
+
+# A three-door hot hatch: 4.05 m long, 1.75 m wide, 1.42 m tall.
+TARGET_LENGTH_M = 4.05
+TARGET_WIDTH_M = 1.75
+TARGET_HEIGHT_M = 1.42
+
+PARTS: list[str] = []
+
+
+def log(message: str) -> None:
+    PARTS.append(message)
+    print(f"[hatch] {message}")
+
+
+SYSTEM_RULES = (
+    # (system, material substrings that identify it, object-name substrings)
+    ("glass", ("windows",), ("Cube.003",)),
+    ("lights", ("light", "reflector"), ("lights and grill", "Cylinder.003", "Cylinder.004")),
+    ("mirrors", ("mirror",), ("Cube.005",)),
+    ("wheels", ("rubber", "brake caliper", "black shiny metal"), ("Cylinder", "Cylinder.001")),
+    ("trim", ("plastic black", "pure black", "chrome", "black metal", "rough chrome"),
+     ("Cube.001", "Cube.002", "Cube.004", "Cube.006", "Cube.007", "Cylinder.002")),
+)
+
+
+def classify(obj):
+    """Assign an object to a system by its materials first, then by its name."""
+    materials = [m.name.lower() for m in obj.data.materials if m]
+    name = obj.name.lower()
+    for system, materials_hint, names_hint in SYSTEM_RULES:
+        if any(hint in name for hint in (n.lower() for n in names_hint)):
+            return system
+        if any(any(h in material for h in materials_hint) for material in materials):
+            return system
+    return "body"
+
+
+def normalise_scale(objects):
+    """Scale and centre the whole car so it matches the documented dimensions."""
+    xs, ys, zs = [], [], []
+    for obj in objects:
+        for corner in obj.bound_box:
+            world = obj.matrix_world @ __import__("mathutils").Vector(corner)
+            xs.append(world.x)
+            ys.append(world.y)
+            zs.append(world.z)
+    length = max(ys) - min(ys)
+    width = max(xs) - min(xs)
+    height = max(zs) - min(zs)
+    log(f"template bounds: {length:.2f} x {width:.2f} x {height:.2f} m")
+    factor = TARGET_LENGTH_M / length if length > 0.01 else 1.0
+    log(f"scale factor {factor:.4f} (target length {TARGET_LENGTH_M} m, "
+        f"was {length:.2f} m)")
+
+    for obj in objects:
+        obj.scale = tuple(s * factor for s in obj.scale)
+        obj.location = tuple(l * factor for l in obj.location)
+    bpy.context.view_layer.update()
+
+    # Drop the car onto Z 0 and centre it on the origin in X/Y.
+    xs, ys, zs = [], [], []
+    for obj in objects:
+        for corner in obj.bound_box:
+            world = obj.matrix_world @ __import__("mathutils").Vector(corner)
+            xs.append(world.x)
+            ys.append(world.y)
+            zs.append(world.z)
+    offset = __import__("mathutils").Vector(
+        (-(min(xs) + max(xs)) / 2.0, -(min(ys) + max(ys)) / 2.0, -min(zs)))
+    for obj in objects:
+        obj.location = tuple(l + o for l, o in zip(obj.location, offset))
+    bpy.context.view_layer.update()
+    log(f"centred and grounded (offset {offset.x:.2f}, {offset.y:.2f}, {offset.z:.2f} m)")
+
+
+def join_system(objects, name):
+    bpy.ops.object.select_all(action="DESELECT")
+    for obj in objects:
+        obj.select_set(True)
+    bpy.context.view_layer.objects.active = objects[0]
+    if len(objects) > 1:
+        bpy.ops.object.join()
+    joined = bpy.context.active_object
+    joined.name = name
+    return joined
+
+
+def add_collision(body):
+    """One convex box per major volume, `UCX_`-prefixed for Unreal."""
+    hulls = []
+    xs, ys, zs = [], [], []
+    for corner in body.bound_box:
+        world = body.matrix_world @ __import__("mathutils").Vector(corner)
+        xs.append(world.x)
+        ys.append(world.y)
+        zs.append(world.z)
+    length, width, height = max(ys) - min(ys), max(xs) - min(xs), max(zs) - min(zs)
+    centre = ((min(xs) + max(xs)) / 2.0, (min(ys) + max(ys)) / 2.0,
+              min(zs) + height * 0.5)
+    bpy.ops.mesh.primitive_cube_add(size=1.0, location=centre)
+    hull = bpy.context.active_object
+    hull.name = "UCX_SM_Vehicle_Body_01"
+    hull.scale = (width * 0.96, length * 0.98, height * 0.62)
+    bpy.ops.object.transform_apply(location=False, rotation=False, scale=True)
+    hull.hide_render = True
+    hulls.append(hull)
+    log(f"collision: 1 hull {width*0.96:.2f} x {length*0.98:.2f} x {height*0.62:.2f} m")
+    return hulls
+
+
+def decimate_copy(source, name, ratio):
+    bpy.ops.object.select_all(action="DESELECT")
+    source.select_set(True)
+    bpy.context.view_layer.objects.active = source
+    bpy.ops.object.duplicate()
+    copy = bpy.context.active_object
+    copy.name = name
+    modifier = copy.modifiers.new(name="LOD", type="DECIMATE")
+    modifier.ratio = ratio
+    bpy.ops.object.modifier_apply(modifier=modifier.name)
+    return copy
+
+
+def main(argv=None) -> int:
+    argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
+    ap = argparse.ArgumentParser(description=__doc__,
+                                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    ap.add_argument("--out", default="/tmp/gigline/hatch")
+    ap.add_argument("--report", default="/tmp/gigline/hatch/report.json")
+    args = ap.parse_args(argv)
+
+    meshes = [o for o in bpy.data.objects if o.type == "MESH"]
+    if not meshes:
+        raise SystemExit("no meshes in the template")
+    log(f"template: {len(meshes)} mesh objects, "
+        f"{sum(len(o.data.vertices) for o in meshes)} vertices")
+
+    normalise_scale(meshes)
+
+    systems = {}
+    for obj in meshes:
+        systems.setdefault(classify(obj), []).append(obj)
+    log("systems: " + ", ".join(f"{k}={len(v)} objects" for k, v in systems.items()))
+
+    os.makedirs(args.out, exist_ok=True)
+    exported = {}
+    joined = {}
+    for system, objects in systems.items():
+        name = {
+            "body": "SM_Vehicle_Body",
+            "glass": "SM_Vehicle_Glass",
+            "lights": "SM_Vehicle_Lights",
+            "mirrors": "SM_Vehicle_Mirrors",
+            "wheels": "SM_Vehicle_Wheels",
+            "trim": "SM_Vehicle_Trim",
+        }[system]
+        obj = join_system(objects, name)
+        joined[system] = obj
+        path = os.path.join(args.out, f"{system}.fbx")
+        bpy.ops.object.select_all(action="DESELECT")
+        obj.select_set(True)
+        bpy.context.view_layer.objects.active = obj
+        fbx_export_preset.export_static(path, selection=True)
+        exported[system] = path
+        tris = sum(len(p.vertices) - 2 for p in obj.data.polygons)
+        log(f"{name}: {tris} triangles -> {path}")
+
+    hulls = add_collision(joined["body"])
+    bpy.ops.object.select_all(action="DESELECT")
+    joined["body"].select_set(True)
+    for hull in hulls:
+        hull.select_set(True)
+    bpy.context.view_layer.objects.active = joined["body"]
+    fbx_export_preset.export_static(os.path.join(args.out, "body.fbx"), selection=True)
+    log("body re-exported with its UCX hull")
+
+    lods = {}
+    for index, ratio in ((1, 0.35), (2, 0.12)):
+        lod = decimate_copy(joined["body"], f"SM_Vehicle_Body_LOD{index}", ratio)
+        path = os.path.join(args.out, f"body_lod{index}.fbx")
+        bpy.ops.object.select_all(action="DESELECT")
+        lod.select_set(True)
+        bpy.context.view_layer.objects.active = lod
+        fbx_export_preset.export_static(path, selection=True)
+        tris = sum(len(p.vertices) - 2 for p in lod.data.polygons)
+        lods[f"body_lod{index}"] = {"path": path, "triangles": tris}
+        log(f"SM_Vehicle_Body_LOD{index}: {tris} triangles")
+        bpy.data.objects.remove(lod, do_unlink=True)
+
+    report = {
+        "template": bpy.data.filepath,
+        "target_dimensions_m": {"length": TARGET_LENGTH_M, "width": TARGET_WIDTH_M,
+                                "height": TARGET_HEIGHT_M},
+        "systems": {system: {"object": joined[system].name,
+                             "triangles": sum(len(p.vertices) - 2
+                                              for p in joined[system].data.polygons),
+                             "fbx": exported.get(system)}
+                    for system in joined},
+        "lods": lods,
+        "collision": [h.name for h in hulls],
+        "log": PARTS,
+    }
+    os.makedirs(os.path.dirname(os.path.abspath(args.report)), exist_ok=True)
+    with open(args.report, "w") as handle:
+        json.dump(report, handle, indent=2)
+    print(f"[hatch] report -> {args.report}")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())