Root cause was in the template, not the import path: 'car paint' is a legacy mix-shader
graph. The FBX exporter cannot map that node tree, so SM_Vehicle_Body imported holding
WorldGridMaterial - the engine's checker fallback - and rendered black while Blender showed
red.
Two changes:
- Tools/vehicle_from_template.py converts legacy graphs to a Principled BSDF before export
and picks the SATURATED colour from the mix nodes; a 'brightest wins' rule chose the 0.8
grey diffuse beside the 0.49 red and produced a grey car.
- Tools/ue_vehicle_materials.py creates M_Vehicle_HatchPaint, and the staged body panel
gets it assigned at build time, because a static mesh slot cannot be repointed from
Python after import.
Judge on the new capture: verdict=yes confidence=0.9 - 'a red hatch car with a red body and
dark wheels parked on a road'. The comparison table in Screenshots/README.md now shows both
columns agreeing on colour.
Still open and recorded: the glazing does not read - the greenhouse looks open, so the glass
system is mispositioned or drawn behind the body.
Both floats had different causes and both were measured.
Character: the player start sat at Z 600 while the capsule settles at Z 561 on this
pavement - the QA self-test has been reporting that settle height all along - so the soles
hung 39 cm in the air. The start now uses the measured 561.
Car: the template's lowest geometry is exhaust and underbody, so grounding the model on its
whole bounding box left the tyres 4 cm above the origin. It is grounded on its WHEELS now.
The staged height is 342 rather than the traced road height of 366, because at 367 the
render still showed a gap: the trace and the visible road mesh disagree by about 25 cm at
that spot, and the number is recorded as empirical rather than derived.
Also adds a foot-contact log to the character at BeginPlay (actor Z, ground, capsule half,
mesh bottom, gap) so the next float is a measurement rather than a look.
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.
Chaos drives a skeletal mesh, so the static system split was not drivable on its own. The
builder now also rigs the vehicle: a root bone plus one bone per wheel, every wheel skinned
to its own bone, exported with the character preset. SK_Vehicle_Sedan imports with
SK_Vehicle_Sedan_Skeleton (508 triangles).
Blocked, and recorded as blocked rather than worked around: Chaos needs a PhysicsAsset, and
unreal.PhysicsAssetFactory in 5.8 exposes no mesh property - setting skeletal_mesh fails
with 'Failed to find property'. Bodies cannot be generated from the mesh in a commandlet,
so the asset has to be authored once in the editor or built in C++ with FPhysicsAssetUtils.
Also fixed the build order: the skeletal join destroys the per-system objects, so the
report and LODs read them before the join - the first attempt died with 'StructRNA of type
Object has been removed'.
Follows the vehicle-artist object split, which the first build violated: body, glass,
front and rear lights, mirrors and a single wheel mesh are now separate objects and
separate assets in /Game/Hollywood/Vehicle. A single merged mesh across all systems is
what the skill forbids for a game vehicle, and it also meant glass could not be made
transparent or lights emissive independently.
LODs decimate rather than duplicate: LOD1 38 triangles, LOD2 14, against 132 for LOD0.
The first pass copied the shell unchanged and produced 84-triangle 'LODs' that saved
nothing.
Imports verified with bounds: body 4.76 x 1.76 x 1.28 m, wheel 0.22 x 0.66 x 0.66 m,
which match the modelled dimensions.
Open, recorded: LOD group wiring needs StaticMeshEditorSubsystem.import_lod, which is
unavailable in a headless commandlet, so the LOD meshes sit as their own assets for now.
zwitschi