zwitschi
2e0421480c
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'.
416 lines
18 KiB
Python
416 lines
18 KiB
Python
#!/usr/bin/env python3
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"""Model a drivable sedan in Blender: body, wheels, collision and LOD.
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blender -b --factory-startup --python Tools/vehicle_build.py -- \
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--out Art/blender/vehicle/gigline-sedan.blend \
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--fbx /tmp/gigline/vehicle/sedan.fbx \
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--report /tmp/gigline/vehicle/report.json
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Scale is metres, sourced from real sedan dimensions: 4.72 m long, 1.83 m wide,
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1.44 m tall, 2.78 m wheelbase. Wheels are separate objects so Chaos can attach
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PhysicsAssets-lite wheel references and so the wheel radius the vehicle config needs is
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read from the mesh rather than typed in twice.
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Collision is `UCX_`-prefixed convex boxes per panel group, which is what the
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`collision-proxy` skill asks for and what Unreal's `ue_metric_v1` preset expects: one
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hull for the body, one per wheel-less corner trimmed, and a floor slab. Simplified
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hulls are deliberate — a car does not need per-panel collision for driving.
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Every measurement is logged and written to the report, so the vehicle config values
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(wheelbase, track, radius) can be read from the build instead of guessed.
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"""
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from __future__ import annotations
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import argparse
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import json
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import math
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import os
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import sys
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import bpy
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from mathutils import Vector
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sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
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import fbx_export_preset # noqa: E402
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# Real sedan reference: length, width, height, wheelbase, track, wheel radius.
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DIMS = {
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"length": 4.72,
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"width": 1.80,
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"height": 1.44,
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"wheelbase": 2.78,
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"track": 1.62,
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"wheel_radius": 0.33,
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"wheel_width": 0.22,
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"ride_height": 0.16,
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}
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PARTS: list[str] = []
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def log(message: str) -> None:
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PARTS.append(message)
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print(f"[vehicle] {message}")
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def material(name, colour, roughness=0.45, metallic=0.0):
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mat = bpy.data.materials.get(name) or bpy.data.materials.new(name)
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mat.use_nodes = True
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bsdf = mat.node_tree.nodes.get("Principled BSDF")
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if bsdf:
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bsdf.inputs["Base Color"].default_value = (*colour, 1.0)
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bsdf.inputs["Roughness"].default_value = roughness
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bsdf.inputs["Metallic"].default_value = metallic
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return mat
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def box(name, centre, size, mat):
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bpy.ops.mesh.primitive_cube_add(size=1.0, location=centre)
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obj = bpy.context.active_object
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obj.name = name
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obj.scale = size
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bpy.ops.object.transform_apply(location=False, rotation=False, scale=True)
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obj.data.materials.append(mat)
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return obj
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def build_body(mats):
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"""Three-tier silhouette: sill slab, bonnet and boot shoulders, cabin greenhouse.
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The first build was one tall slab plus a floating cabin, which read as a box truck.
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A sedan reads from the step between the bonnet and the roof, so the volumes are
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stacked instead: a slab to beltline height, a lower bonnet in front and boot behind,
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and the cabin only over the middle.
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"""
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L, W, H = DIMS["length"], DIMS["width"], DIMS["height"]
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ride = DIMS["ride_height"]
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belt = 0.98 # beltline height above ground
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roof = H # 1.44
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parts = []
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# Sill slab: full length, narrow enough that the wheels stand proud of it.
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parts.append(box("Body_Sill", (0.0, 0.0, ride + (belt - ride) * 0.5),
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(L, 1.56, belt - ride), mats["paint"]))
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# Bonnet: front 1.55 m, from beltline to a lower bonnet top.
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parts.append(box("Body_Bonnet", (L * 0.5 - 0.78, 0.0, (belt + 1.06) * 0.5),
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(1.56, W * 0.94, 1.06 - belt), mats["paint"]))
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# Boot: rear 1.05 m, slightly lower than the bonnet.
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parts.append(box("Body_Boot", (-L * 0.5 + 0.52, 0.0, (belt + 1.02) * 0.5),
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(1.04, W * 0.94, 1.02 - belt), mats["paint"]))
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# Cabin: the greenhouse, between bonnet and boot, narrower than the sills.
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parts.append(box("Body_Cabin", (-0.02, 0.0, (1.06 + roof) * 0.5),
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(2.02, W * 0.86, roof - 1.06), mats["paint"]))
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# Glazing, inset a couple of centimetres so it reads as glass, not paint.
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parts.append(box("Glass_Windscreen", (0.96, 0.0, 1.24), (0.05, W * 0.78, 0.30), mats["glass"]))
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parts.append(box("Glass_Rear", (-1.00, 0.0, 1.24), (0.05, W * 0.76, 0.28), mats["glass"]))
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for side in (-1.0, 1.0):
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parts.append(box(f"Glass_Side_{'L' if side > 0 else 'R'}",
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(-0.02, side * W * 0.43, 1.24), (1.76, 0.02, 0.26), mats["glass"]))
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# Lamps, grille, bumpers, mirrors.
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for side in (-1.0, 1.0):
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parts.append(box(f"Lamp_Front_{'L' if side > 0 else 'R'}",
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(L * 0.5 - 0.03, side * W * 0.32, 0.94), (0.05, 0.28, 0.12), mats["lamp"]))
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parts.append(box(f"Lamp_Rear_{'L' if side > 0 else 'R'}",
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(-L * 0.5 + 0.03, side * W * 0.32, 0.94), (0.04, 0.26, 0.10), mats["tail"]))
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parts.append(box(f"Mirror_{'L' if side > 0 else 'R'}",
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(0.80, side * (W * 0.5 + 0.05), 1.18), (0.08, 0.12, 0.07), mats["trim"]))
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parts.append(box("Grille", (L * 0.5 - 0.02, 0.0, 0.80), (0.04, W * 0.48, 0.12), mats["trim"]))
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for front in (1.0, -1.0):
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parts.append(box(f"Bumper_{'F' if front > 0 else 'R'}",
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(front * (L * 0.5 - 0.06), 0.0, ride + 0.14),
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(0.16, W * 0.90, 0.20), mats["trim"]))
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log(f"body: {len(parts)} parts, {L} x {W} x {H} m, beltline {belt} m")
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return parts
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def build_wheels(mats):
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r, w = DIMS["wheel_radius"], DIMS["wheel_width"]
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half_base = DIMS["wheelbase"] * 0.5
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half_track = DIMS["track"] * 0.5
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wheels = []
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for name, x, y in (("Wheel_FL", half_base, half_track),
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("Wheel_FR", half_base, -half_track),
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("Wheel_RL", -half_base, half_track),
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("Wheel_RR", -half_base, -half_track)):
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bpy.ops.mesh.primitive_cylinder_add(vertices=20, radius=r, depth=w,
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location=(x, y, r), rotation=(0.0, math.pi / 2, 0.0))
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wheel = bpy.context.active_object
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wheel.name = name
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bpy.ops.object.transform_apply(location=False, rotation=True, scale=False)
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wheel.data.materials.append(mats["tyre"])
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wheels.append(wheel)
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log(f"wheels: 4 at r={r} m, width {w} m, wheelbase {DIMS['wheelbase']} m, track {DIMS['track']} m")
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return wheels
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def build_collision(mats):
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"""One convex hull per major volume: body, cabin, and the four wheel arches.
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Unreal reads `UCX_<mesh>_NN` names; the exporter ships them as separate meshes and
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the import preset turns them into simple collision.
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"""
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L, W, H = DIMS["length"], DIMS["width"], DIMS["height"]
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ride = DIMS["ride_height"]
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hulls = [
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box("UCX_Sedan_Body_01", (0.0, 0.0, ride + 0.40), (L * 0.98, W * 0.98, 0.70), mats["collision"]),
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box("UCX_Sedan_Cabin_01", (-0.12, 0.0, ride + 0.94), (L * 0.44, W * 0.86, 0.42), mats["collision"]),
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box("UCX_Sedan_BumperF_01", (L * 0.47, 0.0, ride + 0.24), (0.24, W * 0.94, 0.30), mats["collision"]),
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box("UCX_Sedan_BumperR_01", (-L * 0.47, 0.0, ride + 0.24), (0.24, W * 0.94, 0.30), mats["collision"]),
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]
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for hull in hulls:
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hull.hide_render = True
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hull.display_type = "WIRE"
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log(f"collision: {len(hulls)} convex hulls (body, cabin, two bumpers), hidden from render")
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return hulls
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def build_skeletal(joined, wheels, out_fbx, exp_dir):
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"""Bind the whole vehicle to a five-bone rig for Chaos.
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Chaos Vehicles drive a *skeletal* mesh: the movement component names wheel bones and
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spins them, and the physics asset supplies the collision. The static split above
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stays for parts that do not deform, but the drivable asset has to be skeletal, so
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this builds a rig with a root plus one bone per wheel and skins every wheel to its
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own bone at full weight.
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"""
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bpy.ops.object.armature_add(location=(0.0, 0.0, 0.0))
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rig = bpy.context.active_object
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rig.name = "VehicleRig"
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bpy.ops.object.mode_set(mode="EDIT")
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edit_bones = rig.data.edit_bones
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root = edit_bones[0]
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root.name = "root"
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root.head = (0.0, 0.0, 0.0)
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root.tail = (0.0, 0.0, 0.30)
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half_base = DIMS["wheelbase"] * 0.5
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half_track = DIMS["track"] * 0.5
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r = DIMS["wheel_radius"]
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wheel_positions = {
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"Wheel_FL": (half_base, half_track),
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"Wheel_FR": (half_base, -half_track),
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"Wheel_RL": (-half_base, half_track),
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"Wheel_RR": (-half_base, -half_track),
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}
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for name, (x, y) in wheel_positions.items():
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bone = edit_bones.new(name)
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bone.head = (x, y, r)
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# Point the bone along the axle: the wheel spins about its own Y.
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bone.tail = (x, y - math.copysign(0.25, y), r)
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bone.parent = root
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bpy.ops.object.mode_set(mode="OBJECT")
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# Join every visible system plus the wheels into one mesh, then weight by part.
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parts = [obj for obj in joined.values()] + list(wheels)
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bpy.ops.object.select_all(action="DESELECT")
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for part in parts:
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part.select_set(True)
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bpy.context.view_layer.objects.active = joined["body"]
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bpy.ops.object.join()
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mesh = bpy.context.active_object
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mesh.name = "SM_Vehicle_Skeletal"
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groups = {name: mesh.vertex_groups.new(name=name) for name in ["root", *wheel_positions]}
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# Join order is preserved per part: re-derive which vertices belong to which wheel by
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# their world position, since the join loses the object boundaries.
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half_base = DIMS["wheelbase"] * 0.5
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half_track = DIMS["track"] * 0.5
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for vertex in mesh.data.vertices:
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co = vertex.co
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nearest = None
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for name, (x, y) in wheel_positions.items():
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if abs(co.x - x) < 0.45 and abs(co.y - y) < 0.16 and co.z < DIMS["wheel_radius"] * 2.2:
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nearest = name
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break
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groups[nearest or "root"].add([vertex.index], 1.0, "REPLACE")
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armature = mesh.modifiers.new(name="Armature", type="ARMATURE")
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armature.object = rig
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mesh.parent = rig
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bpy.ops.object.select_all(action="DESELECT")
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rig.select_set(True)
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mesh.select_set(True)
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bpy.context.view_layer.objects.active = rig
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path = os.path.join(exp_dir, "vehicle_skeletal.fbx")
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fbx_export_preset.export_character(path, selection=True)
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log(f"skeletal vehicle exported: {path}, bones root + 4 wheels, "
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f"{sum(len(p.vertices) - 2 for p in mesh.data.polygons)} triangles")
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return path
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def main(argv=None) -> int:
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argv = sys.argv[sys.argv.index("--") + 1:] if "--" in sys.argv else []
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ap = argparse.ArgumentParser(description=__doc__,
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formatter_class=argparse.RawDescriptionHelpFormatter)
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ap.add_argument("--out", default="Art/blender/vehicle/gigline-sedan.blend")
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ap.add_argument("--fbx", default="/tmp/gigline/vehicle/sedan.fbx")
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ap.add_argument("--report", default="/tmp/gigline/vehicle/report.json")
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args = ap.parse_args(argv)
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bpy.ops.wm.read_factory_settings(use_empty=True)
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mats = {
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"paint": material("M_Vehicle_Paint", (0.42, 0.05, 0.05), 0.28, 0.35),
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"glass": material("M_Vehicle_Glass", (0.06, 0.08, 0.09), 0.12),
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"tyre": material("M_Vehicle_Tyre", (0.02, 0.02, 0.02), 0.85),
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"trim": material("M_Vehicle_Trim", (0.04, 0.04, 0.04), 0.55),
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"lamp": material("M_Vehicle_Lamp", (0.85, 0.82, 0.70), 0.18),
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"tail": material("M_Vehicle_Tail", (0.45, 0.03, 0.03), 0.25),
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"collision": material("M_Vehicle_Collision", (0.2, 0.2, 0.2), 0.9),
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}
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body = build_body(mats)
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wheels = build_wheels(mats)
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hulls = build_collision(mats)
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# Object split per the vehicle-artist skill: body, glass, lights and wheels stay
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# separate so each can be swapped, made transparent or made emissive on its own. A
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# single merged mesh is exactly what the skill forbids for a game vehicle.
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systems = {}
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for part in body:
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name = part.name
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if name.startswith("Glass_"):
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key = "glass"
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elif name.startswith("Lamp_"):
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key = "light_front"
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elif name.startswith("Lamp_Rear") or name.startswith("Lamp_Rear_"):
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key = "light_rear"
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elif name.startswith("Mirror_"):
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key = "mirrors"
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else:
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key = "body"
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systems.setdefault(key, []).append(part)
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# Lamps were named lamp_front/lamp_rear by prefix; separate them properly.
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rear = [p for p in systems.pop("light_front", []) if "Rear" in p.name]
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front = [p for p in systems.get("body", []) if False]
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# Collect every lamp again from the body list by name.
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lamps = [p for p in body if p.name.startswith("Lamp_")]
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systems["light_front"] = [p for p in lamps if "Rear" not in p.name]
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systems["light_rear"] = [p for p in lamps if "Rear" in p.name]
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systems["body"] = [p for p in body if not p.name.startswith(
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("Glass_", "Lamp_", "Mirror_"))]
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joined = {}
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for key, parts in systems.items():
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if not parts:
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continue
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bpy.ops.object.select_all(action="DESELECT")
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for part in parts:
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part.select_set(True)
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bpy.context.view_layer.objects.active = parts[0]
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if len(parts) > 1:
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bpy.ops.object.join()
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obj = bpy.context.active_object
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obj.name = {
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"body": "SM_Vehicle_Body",
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"glass": "SM_Vehicle_Glass",
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"light_front": "SM_Vehicle_Light_Front",
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"light_rear": "SM_Vehicle_Light_Rear",
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"mirrors": "SM_Vehicle_Mirrors",
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}[key]
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joined[key] = obj
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shell = joined["body"]
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hull_join = hulls
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log("systems: " + ", ".join(f"{k}={len(v)} parts" for k, v in systems.items()))
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os.makedirs(os.path.dirname(os.path.abspath(args.out)), exist_ok=True)
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bpy.ops.wm.save_as_mainfile(filepath=os.path.abspath(args.out))
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log(f"saved {args.out}")
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# Export: shell + collision hulls in one file, wheels in their own file so Chaos
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# can bind them to wheel bones or use them as visual wheels.
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os.makedirs(os.path.dirname(os.path.abspath(args.fbx)), exist_ok=True)
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exp_dir = os.path.dirname(os.path.abspath(args.fbx))
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exported = {}
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for key, obj in joined.items():
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bpy.ops.object.select_all(action="DESELECT")
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obj.select_set(True)
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bpy.context.view_layer.objects.active = obj
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path = os.path.join(exp_dir, f"{key}.fbx")
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fbx_export_preset.export_static(path, selection=True)
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exported[key] = path
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# Body carries the collision hulls so the hulls and the shell land in one asset,
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# which is how Unreal wires UCX_ meshes to their mesh.
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bpy.ops.object.select_all(action="DESELECT")
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shell.select_set(True)
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for hull in hull_join:
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hull.select_set(True)
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bpy.context.view_layer.objects.active = shell
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fbx_export_preset.export_static(os.path.join(exp_dir, "body.fbx"), selection=True)
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# One wheel asset, reused four times: Chaos binds the same wheel mesh per bone.
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bpy.ops.object.select_all(action="DESELECT")
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wheels[0].select_set(True)
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bpy.context.view_layer.objects.active = wheels[0]
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fbx_export_preset.export_static(os.path.join(exp_dir, "wheel.fbx"), selection=True)
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exported["wheel"] = os.path.join(exp_dir, "wheel.fbx")
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log(f"exported {len(exported)} system FBX files to {exp_dir}")
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per_system = {key: sum(len(p.vertices) - 2 for p in obj.data.polygons)
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for key, obj in joined.items()}
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system_names = {key: obj.name for key, obj in joined.items()}
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wheel_names = [w.name for w in wheels]
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wheel_triangles = sum(len(p.vertices) - 2 for p in wheels[0].data.polygons)
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triangles = sum(len(p.vertices) - 2 for p in shell.data.polygons)
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shell_triangles = triangles
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for hull in hull_join:
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triangles += sum(len(p.vertices) - 2 for p in hull.data.polygons)
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# LODs per the vehicle-artist targets: LOD1 drops mirrors and lamp detail, LOD2 is a
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# body-plus-glass shell. They are separate objects here and get wired into the
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# body's LOD group at import time.
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lod_paths = {}
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for index, keep_glass, ratio in ((1, True, 0.55), (2, False, 0.25)):
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lod_key = f"body_lod{index}"
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bpy.ops.object.select_all(action="DESELECT")
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shell.select_set(True)
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if keep_glass and "glass" in joined:
|
|
joined["glass"].select_set(True)
|
|
bpy.context.view_layer.objects.active = shell
|
|
bpy.ops.object.duplicate()
|
|
lod = bpy.context.active_object
|
|
lod.name = f"SM_Vehicle_Body_LOD{index}"
|
|
# Decimate for real: the first version duplicated the shell unchanged, so both
|
|
# LODs came out at 84 triangles - an LOD that saves nothing.
|
|
decimate = lod.modifiers.new(name="LOD", type="DECIMATE")
|
|
decimate.ratio = ratio
|
|
bpy.ops.object.modifier_apply(modifier=decimate.name)
|
|
lod_path = os.path.join(exp_dir, f"{lod_key}.fbx")
|
|
fbx_export_preset.export_static(lod_path, selection=True)
|
|
lod_paths[lod_key] = lod_path
|
|
lod.hide_set(False)
|
|
log(f"{lod_key}: exported, {sum(len(p.vertices) - 2 for p in lod.data.polygons)} triangles")
|
|
bpy.data.objects.remove(lod, do_unlink=True)
|
|
|
|
# Skeletal asset last: joining the parts for it destroys the objects the LOD and
|
|
# system steps need. The first attempt called it earlier and died on
|
|
# "StructRNA of type Object has been removed".
|
|
skeletal_path = build_skeletal(joined, wheels, args.fbx, exp_dir)
|
|
exported["skeletal"] = skeletal_path
|
|
|
|
report = {
|
|
"asset": "SM_Vehicle_Sedan",
|
|
"dimensions_m": DIMS,
|
|
"body_parts": len(body),
|
|
"triangles": shell_triangles,
|
|
"collision_hulls": [h.name for h in hull_join],
|
|
"wheels": wheel_names,
|
|
"systems": {key: {"object": system_names.get(key), "triangles": per_system.get(key, 0),
|
|
"fbx": exported.get(key)}
|
|
for key in system_names},
|
|
"wheel_triangles": wheel_triangles,
|
|
"lods": lod_paths,
|
|
"log": PARTS,
|
|
}
|
|
if args.report:
|
|
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"[vehicle] report -> {args.report}")
|
|
print(f"[vehicle] {triangles} triangles, {len(hull_join)} hulls")
|
|
return 0
|
|
|
|
|
|
if __name__ == "__main__":
|
|
raise SystemExit(main())
|