212 lines
8.2 KiB
Python
212 lines
8.2 KiB
Python
"""Blender 内运行：高低模 Cycles 烘焙，低模 UV 上出 normal/ao/color/metallic/roughness。
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调用：blender -b --factory-startup --python bl_bake.py -- \
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<high.fbx> <low.fbx> <outdir> <size> <ray_distance|auto> <samples>
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"""
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import math
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import os
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import sys
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sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
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DEFAULT_RAY_PCT = 0.02 # 自动射线距离 = 低模包围盒对角线 * 2%
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BBOX_TOL = 0.10 # 高低模包围盒尺寸相对差警告阈值
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# (输出名, bake type, EMIT 来源的 Principled 输入, 目标图颜色空间)
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BAKE_PASSES = [
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("normal", 'NORMAL', None, 'Non-Color'),
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("ao", 'AO', None, 'Non-Color'),
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("color", 'EMIT', 'Base Color', 'sRGB'),
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("metallic", 'EMIT', 'Metallic', 'Non-Color'),
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("roughness", 'EMIT', 'Roughness', 'Non-Color'),
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]
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def estimate_ray_distance(bbox_dims, pct=DEFAULT_RAY_PCT):
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"""低模包围盒尺寸 (dx,dy,dz) -> 射线距离 = 对角线长 * pct。"""
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return math.sqrt(sum(d * d for d in bbox_dims)) * pct
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def output_stem(low_name):
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"""低模名去掉 _low 后缀作为输出前缀（对齐工具3纯网格贴图命名约定）。"""
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return low_name[:-4] if low_name.endswith("_low") else low_name
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def bbox_mismatch(high_dims, low_dims, tol=BBOX_TOL):
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"""任一轴尺寸相对差超 tol 返回 True；接近 0 的轴忽略（平面模型）。"""
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for h, l in zip(high_dims, low_dims):
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m = max(abs(h), abs(l))
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if m > 1e-9 and abs(h - l) / m > tol:
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return True
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return False
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# ---------------- 以下仅在 Blender 内执行 ----------------
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def _import_fbx_joined(path, warnings):
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"""导入 FBX 并把其中所有 mesh join 成单对象；无 mesh 返回 None。"""
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import bpy
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from bl_decimate import join_meshes
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before = set(bpy.data.objects)
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bpy.ops.import_scene.fbx(filepath=path)
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new = [o for o in bpy.data.objects if o not in before]
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meshes = [o for o in new if o.type == 'MESH']
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skipped = [o.name for o in new if o.type != 'MESH']
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if skipped:
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warnings.append("%s：忽略非 mesh 对象 %s"
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% (os.path.basename(path), ", ".join(skipped)))
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if not meshes:
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return None
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return join_meshes(meshes)
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def _setup_bake_target(low, stem):
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"""低模换成单一烘焙材质，返回接收烘焙结果的 image 节点。"""
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import bpy
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mat = bpy.data.materials.new(stem)
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mat.use_nodes = True
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node = mat.node_tree.nodes.new('ShaderNodeTexImage')
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mat.node_tree.nodes.active = node
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low.data.materials.clear()
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low.data.materials.append(mat)
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return mat, node
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def _high_materials(high):
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return [s.material for s in high.material_slots if s.material]
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def _rewire_emit(mat, input_name, warnings):
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"""把 Principled 指定输入（连线或常量）改接 Emission 直连输出，供 EMIT 烘焙。"""
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import bpy
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if not mat.use_nodes:
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mat.use_nodes = True
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nt = mat.node_tree
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bsdf = next((n for n in nt.nodes if n.type == 'BSDF_PRINCIPLED'), None)
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out = next((n for n in nt.nodes if n.type == 'OUTPUT_MATERIAL'), None)
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if out is None:
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out = nt.nodes.new('ShaderNodeOutputMaterial')
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emit = nt.nodes.get("mt_emit")
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if emit is None:
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emit = nt.nodes.new('ShaderNodeEmission')
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emit.name = "mt_emit"
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for l in list(emit.inputs['Color'].links):
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nt.links.remove(l)
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if bsdf is None:
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warnings.append("材质 %s 无 Principled BSDF，%s 用 0.5 灰常量"
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% (mat.name, input_name))
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emit.inputs['Color'].default_value = (0.5, 0.5, 0.5, 1.0)
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else:
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sock = bsdf.inputs[input_name]
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if sock.is_linked:
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nt.links.new(sock.links[0].from_socket, emit.inputs['Color'])
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else:
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v = sock.default_value
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if isinstance(v, float):
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# 该通道无贴图，把常量值直接烘入
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warnings.append("%s.%s 无贴图，(常量) %.3f 烘入" % (mat.name, input_name, v))
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emit.inputs['Color'].default_value = (v, v, v, 1.0)
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else: # Base Color 是 4 分量
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# 该通道无贴图，把常量色直接烘入
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warnings.append("%s.%s 无贴图，(常量色 %.3f/%.3f/%.3f) 烘入"
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% (mat.name, input_name, v[0], v[1], v[2]))
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emit.inputs['Color'].default_value = (v[0], v[1], v[2], 1.0)
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for l in list(out.inputs['Surface'].links):
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nt.links.remove(l)
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nt.links.new(emit.outputs['Emission'], out.inputs['Surface'])
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def _bake_pass(low, high, target_node, name, bake_type, size, colorspace,
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ray, samples, outdir, stem):
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"""执行一个烘焙 pass 并保存 PNG，返回文件名。"""
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import bpy
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img = bpy.data.images.new("mt_bake_" + name, size, size, alpha=False)
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img.colorspace_settings.name = colorspace
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target_node.image = img
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bpy.ops.object.select_all(action='DESELECT')
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high.select_set(True)
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low.select_set(True)
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bpy.context.view_layer.objects.active = low
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bpy.context.scene.cycles.samples = samples
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kwargs = dict(type=bake_type, use_selected_to_active=True,
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cage_extrusion=ray, max_ray_distance=ray * 2.0,
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margin=16, use_clear=True)
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if bake_type == 'NORMAL':
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kwargs["normal_space"] = 'TANGENT' # OpenGL +Y
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bpy.ops.object.bake(**kwargs)
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path = os.path.abspath(os.path.join(outdir, "%s_%s.png" % (stem, name)))
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img.filepath_raw = path
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img.file_format = 'PNG'
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img.save()
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bpy.data.images.remove(img)
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return os.path.basename(path)
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def main():
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import bpy
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import json
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argv = sys.argv[sys.argv.index("--") + 1:]
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high_fbx, low_fbx, outdir = argv[0], argv[1], argv[2]
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size, ray_arg, ao_samples = int(argv[3]), argv[4], int(argv[5])
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warnings = []
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bpy.ops.wm.read_factory_settings(use_empty=True)
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high = _import_fbx_joined(high_fbx, warnings)
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low = _import_fbx_joined(low_fbx, warnings)
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if high is None or low is None:
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print("MT_SUMMARY " + json.dumps(
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{"error": "高模或低模 FBX 中没有 mesh"}, ensure_ascii=False))
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return
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if not low.data.uv_layers:
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print("MT_SUMMARY " + json.dumps(
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{"error": "低模没有 UV 层，请先用 model_decimate.py 生成"},
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ensure_ascii=False))
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return
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high_dims, low_dims = tuple(high.dimensions), tuple(low.dimensions)
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if bbox_mismatch(high_dims, low_dims):
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warnings.append("高低模包围盒尺寸差异超 %d%%：高 %s 低 %s，确认是同一模型且坐标已对齐"
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% (BBOX_TOL * 100,
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[round(d, 3) for d in high_dims],
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[round(d, 3) for d in low_dims]))
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ray = estimate_ray_distance(low_dims) if ray_arg == "auto" else float(ray_arg)
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stem = output_stem(os.path.splitext(os.path.basename(low_fbx))[0])
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os.makedirs(outdir, exist_ok=True)
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scene = bpy.context.scene
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scene.render.engine = 'CYCLES'
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scene.cycles.device = 'CPU'
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bake_mat, target_node = _setup_bake_target(low, stem)
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mats = _high_materials(high)
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outputs = {}
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for name, bake_type, emit_input, colorspace in BAKE_PASSES:
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if emit_input is not None: # EMIT trick：先改写全部高模材质
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for m in mats:
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_rewire_emit(m, emit_input, warnings)
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samples = ao_samples if bake_type == 'AO' else 1
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outputs[name] = _bake_pass(low, high, target_node, name, bake_type,
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size, colorspace, ray, samples, outdir, stem)
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# 导出低模：剥掉烘焙 image 节点，材质名保留 stem（工具3 兜底识别用）
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bake_mat.node_tree.nodes.remove(target_node)
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out_fbx = os.path.join(outdir, stem + ".fbx")
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bpy.ops.object.select_all(action='DESELECT')
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low.select_set(True)
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bpy.ops.export_scene.fbx(filepath=out_fbx, use_selection=True,
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path_mode='STRIP', embed_textures=False)
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print("MT_SUMMARY " + json.dumps(
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{"stem": stem, "fbx": os.path.basename(out_fbx), "outputs": outputs,
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"size": size, "ray_distance": round(ray, 6),
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"high_tris": len(high.data.polygons), "low_tris": len(low.data.polygons),
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"warnings": warnings}, ensure_ascii=False))
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if __name__ == "__main__" and "--" in sys.argv:
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main()
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