zwitschi
ecdd8208db
Wheel axles were vertical in Unreal (the FBX armature conversion rolled them 90 deg about X). Fix: axis_forward:X in the character preset and a Blender-Z wheel tail so the axle lands on Unreal Y. This is correct (reference pose FL roll 180 / FR roll 0) but does not fix the reverse: -drivetest still -2737 cm/s, and FinalRatio sign is a no-op. The remaining cause is the Chaos wheel spin-axis convention or engine torque sign.
109 lines
4.5 KiB
Python
109 lines
4.5 KiB
Python
#!/usr/bin/env python3
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"""The one FBX export preset for this project ("ue_metric_v1"/"ue_character_v1").
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Before this module the same `bpy.ops.export_scene.fbx(...)` argument block was
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copied into six scripts (hero, frontage, north buildings, site, scale test, MPFB
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character). They had already drifted only by accident, and every one of them
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carried `mesh_smooth_type="OFF"` — which is why Unreal logged "No smoothing group
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information was found for this mesh" on every import and round parts rendered
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faceted. One preset, one place to fix that.
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Use from inside Blender:
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import sys, os
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sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "Tools"))
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import fbx_export_preset as preset
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preset.export_static(path) # whole scene, MESH only
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preset.export_static(path, selection=True) # selected objects only
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preset.export_character(path) # armature + mesh, character flags
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`preset_kwargs()` is pure (no `bpy`), so the argument set can be unit-tested
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without Blender — see Tools/tests/test_fbx_export_preset.py.
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Why these values:
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* `FBX_SCALE_NONE` + `apply_unit_scale` keeps Blender metres → Unreal centimetres
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at exactly ×100, verified by the three-cube scale test (1 m → 100.00 uu).
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* `axis_forward="-Y"`, `axis_up="Z"` is the project's recorded mapping: east → +X,
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north → −Y, up → +Z.
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* `mesh_smooth_type="FACE"` exports smoothing groups. `"OFF"` (the old value)
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drops them, so Unreal rebuilds flat normals and every cylinder is faceted.
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* `use_mesh_modifiers=True` bakes the bevel/modifier stack at export; the source
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`.blend` stays non-destructive.
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"""
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from __future__ import annotations
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# Shared by every mesh export. Values are the recorded ue_metric_v1 preset.
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_METRIC = {
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"object_types": {"MESH"},
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"apply_unit_scale": True,
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"apply_scale_options": "FBX_SCALE_NONE",
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"axis_forward": "-Y",
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"axis_up": "Z",
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"use_space_transform": True,
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"use_mesh_modifiers": True,
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"mesh_smooth_type": "FACE",
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"path_mode": "AUTO",
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"bake_space_transform": False,
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}
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# Character exports differ only in the object set and the armature/path flags.
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#
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# Animation export (added for the 0.2.0 animation set): without `bake_anim` the
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# exporter silently writes a static bind pose even when the armature carries
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# actions, and Unreal then imports a character with no AnimSequence and no error.
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# `bake_anim_use_all_actions` exports every action as its own clip; NLA strips are
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# off because the project does not author NLA. `bake_anim_simplify_factor=0.0`
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# keeps the sampled keys exactly as authored - the clips are short, so the size
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# cost is irrelevant and a simplified curve would drift from the source poses.
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_CHARACTER = dict(
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_METRIC,
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object_types={"ARMATURE", "MESH"},
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axis_forward="X",
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add_leaf_bones=False,
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path_mode="COPY",
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embed_textures=False,
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bake_anim=True,
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bake_anim_use_all_actions=True,
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bake_anim_use_nla_strips=False,
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bake_anim_force_startend_keying=True,
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bake_anim_simplify_factor=0.0,
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)
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PRESETS = {"ue_metric_v1": _METRIC, "ue_character_v1": _CHARACTER}
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def preset_kwargs(preset: str = "ue_metric_v1", selection: bool = False, **overrides) -> dict:
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"""Return the `bpy.ops.export_scene.fbx` argument dict (no `bpy` needed).
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`preset` selects the base set, `selection` decides whether only selected
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objects are exported, and `overrides` wins last for the rare special case.
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"""
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if preset not in PRESETS:
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raise KeyError(f"unknown preset {preset!r}; known: {sorted(PRESETS)}")
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kwargs = dict(PRESETS[preset])
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kwargs["use_selection"] = bool(selection)
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kwargs.update(overrides)
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if "filepath" in kwargs:
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raise ValueError("pass the path to export_static/export_character, not as an override")
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return kwargs
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def _export(path: str, preset: str, selection: bool, overrides: dict) -> str:
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import bpy # imported here so `preset_kwargs` stays usable without Blender
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kwargs = preset_kwargs(preset, selection=selection, **overrides)
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bpy.ops.export_scene.fbx(filepath=path, **kwargs)
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return path
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def export_static(path: str, selection: bool = False, **overrides) -> str:
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"""Export meshes with the ue_metric_v1 preset. Returns the path."""
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return _export(path, "ue_metric_v1", selection, overrides)
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def export_character(path: str, selection: bool = False, **overrides) -> str:
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"""Export armature + mesh with the ue_character_v1 preset. Returns the path."""
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return _export(path, "ue_character_v1", selection, overrides)
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