ud18010andClaude Opus 4.8
97995306ac
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
414 lines
16 KiB
Python
414 lines
16 KiB
Python
"""Blender 内运行：FBX 减面到指定三角面数 + UV 重展（锐边 seam 或 Smart UV Project）。
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调用：blender -b --factory-startup --python bl_decimate.py -- <src.fbx> <out.fbx> <target_tris> [seam|smart]
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"""
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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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TOLERANCE = 0.03 # 面数相对误差容忍
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MAX_RETRY = 2 # ratio 修正轮数上限
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def decimate_ratio(target, cur):
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"""Decimate collapse ratio；cur <= target 或非法时返回 1.0（不减面）。"""
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if cur <= 0 or cur <= target:
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return 1.0
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return target / float(cur)
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def within_tolerance(target, actual, tol=TOLERANCE):
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"""减面结果是否落在目标 ±tol 内。"""
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if target <= 0:
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return False
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return abs(actual - target) <= target * tol
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UV_FLIP_TOL = 0.02 # 质量门：UV 翻转面占比超此值回退 smart_project
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UV_OVERLAP_TOL = 0.08 # 质量门：UV 重叠面占比阈值（手工 UV 同口径约 5%，灾难性失败 >20%）
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def uv_gate_ok(flipped, overlap, overlap_tol=UV_OVERLAP_TOL):
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"""UV 质量门：翻转按 UV_FLIP_TOL 固定，重叠按 overlap_tol（默认 UV_OVERLAP_TOL）。
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overlap 为 None（op 不可用）按 0 处理。"""
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return flipped <= UV_FLIP_TOL and (overlap or 0.0) <= overlap_tol
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def uvpm_mode_label(base, applied):
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"""UV 模式标注：UVPackmaster 排布生效时加 +uvpm 后缀。"""
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return base + "+uvpm" if applied else base
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def pick_best_candidate(candidates, overlap_tol=UV_OVERLAP_TOL):
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"""从候选 UV 指标 dict 列表选过质量门且岛数最少者；无过门候选返回 None。
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overlap_tol 覆盖重叠容忍。每个 candidate 至少含 flipped/overlap/islands。"""
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passing = [c for c in candidates
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if uv_gate_ok(c["flipped"], c["overlap"], overlap_tol)]
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if not passing:
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return None
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return min(passing, key=lambda c: c["islands"])
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def count_islands(n_faces, adjacent_pairs):
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"""union-find 数 UV 岛：n_faces 个面，adjacent_pairs 为 UV 连续的面索引对。"""
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parent = list(range(n_faces))
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def find(i):
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while parent[i] != i:
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parent[i] = parent[parent[i]]
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i = parent[i]
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return i
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for a, b in adjacent_pairs:
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ra, rb = find(a), find(b)
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if ra != rb:
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parent[ra] = rb
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return len({find(i) for i in range(n_faces)})
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def flipped_fraction(signed_areas):
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"""UV 面签名面积为负（翻转）的占比。"""
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if not signed_areas:
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return 0.0
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return sum(1 for a in signed_areas if a < 0) / float(len(signed_areas))
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def fill_ratio(abs_areas):
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"""UV 空间利用率：面积和（重叠会虚高，截断到 1.0）。"""
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return min(1.0, sum(abs_areas))
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# ---------------- 以下仅在 Blender 内执行 ----------------
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def join_meshes(objs):
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"""多 mesh join 成单对象，返回结果对象（bl_bake 复用）。"""
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import bpy
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bpy.ops.object.select_all(action='DESELECT')
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for o in objs:
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o.select_set(True)
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bpy.context.view_layer.objects.active = objs[0]
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if len(objs) > 1:
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bpy.ops.object.join()
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return bpy.context.view_layer.objects.active
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def _apply_modifier(obj, mod):
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import bpy
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.modifier_apply(modifier=mod.name)
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def _triangulate(obj):
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mod = obj.modifiers.new("mt_tri", 'TRIANGULATE')
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_apply_modifier(obj, mod)
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def _decimate(obj, ratio):
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mod = obj.modifiers.new("mt_dec", 'DECIMATE')
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mod.decimate_type = 'COLLAPSE'
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mod.ratio = ratio
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mod.use_collapse_triangulate = True
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_apply_modifier(obj, mod)
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SEAM_ANGLE_DEG = 66.0 # 锐边阈值：两面夹角超此值标 seam
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PACK_MARGIN = 0.002 # 岛间距 ≈ 2048 图 4px
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UVPM_EXT = "bl_ext.user_default.uvpackmaster4" # UVPackmaster 4 扩展模块名
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UVPM_PIXEL_MARGIN = 4 # UVPM 岛间距（像素），与 PACK_MARGIN * UVPM_TEX_SIZE 同口径
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UVPM_TEX_SIZE = 2048
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SEAM_ANGLE_SWEEP = (55.0, 45.0, 35.0) # 首选 SEAM_ANGLE_DEG 不过门时依次下探的 seam 角度
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STRETCH_ITERS = 30 # minimize_stretch 松弛迭代次数
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def _clear_uv_layers(mesh):
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while mesh.uv_layers:
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mesh.uv_layers.remove(mesh.uv_layers[0])
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def _unwrap_smart(obj):
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"""Smart UV Project（原路径，也是质量门的回退路径）。"""
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import bpy
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import math
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_clear_uv_layers(obj.data)
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.mode_set(mode='EDIT')
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bpy.ops.mesh.select_all(action='SELECT')
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bpy.ops.uv.smart_project(angle_limit=math.radians(66.0), island_margin=PACK_MARGIN)
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bpy.ops.object.mode_set(mode='OBJECT')
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def _unwrap_seam(obj, warnings, seam_angle_deg=SEAM_ANGLE_DEG):
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"""锐边标 seam -> MINIMUM_STRETCH/ANGLE_BASED 展开 -> 松弛 -> 纹素均衡 -> pack。
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seam_angle_deg 可变以支持角度扫描；重跑前清掉上一档残留 seam。"""
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import bpy
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import math
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_clear_uv_layers(obj.data)
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obj.data.uv_layers.new()
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.mode_set(mode='EDIT')
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bpy.ops.mesh.select_mode(type='EDGE')
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# 清掉上一档角度残留 seam（同一对象多角度扫描时必须；同时丢弃源资产自带 seam，保证确定性）
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bpy.ops.mesh.select_all(action='SELECT')
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bpy.ops.mesh.mark_seam(clear=True)
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# 锐边标 seam：接缝只落在硬边处，平滑区域保持整岛
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bpy.ops.mesh.select_all(action='DESELECT')
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bpy.ops.mesh.edges_select_sharp(sharpness=math.radians(seam_angle_deg))
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bpy.ops.mesh.mark_seam(clear=False)
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bpy.ops.mesh.select_all(action='SELECT')
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try:
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bpy.ops.uv.unwrap(method='MINIMUM_STRETCH', margin=PACK_MARGIN)
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except TypeError: # 老版本无 SLIM 枚举
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warnings.append("MINIMUM_STRETCH 不可用，展开改用 ANGLE_BASED")
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bpy.ops.uv.unwrap(method='ANGLE_BASED', margin=PACK_MARGIN)
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try: # 角度松弛：压翻转/拉伸
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bpy.ops.uv.minimize_stretch(iterations=STRETCH_ITERS)
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except (RuntimeError, TypeError) as e:
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warnings.append("minimize_stretch 不可用（%s），跳过松弛" % e)
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try: # 统一纹素密度，避免大岛霸占分辨率
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bpy.ops.uv.average_islands_scale()
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except (RuntimeError, TypeError) as e:
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warnings.append("average_islands_scale 不可用（%s），跳过纹素均衡" % e)
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try:
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bpy.ops.uv.pack_islands(rotate=True, margin=PACK_MARGIN)
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except RuntimeError: # headless 上下文不满足时靠 unwrap 自带打包
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warnings.append("pack_islands 不可用，沿用 unwrap 自带布局")
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bpy.ops.object.mode_set(mode='OBJECT')
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def _collect_uv_metrics(obj):
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"""bmesh 提取 UV 指标：岛数（UV 连续边并查集）、利用率、翻转占比、重叠占比。"""
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import bmesh
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bm = bmesh.new()
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bm.from_mesh(obj.data)
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uv = bm.loops.layers.uv.active
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pairs = []
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for e in bm.edges:
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if len(e.link_faces) != 2:
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continue
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f1, f2 = e.link_faces
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cont = True
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for v in e.verts: # 两面在该边两端 UV 一致 => UV 连续（同岛）
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l1 = next(l for l in f1.loops if l.vert == v)
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l2 = next(l for l in f2.loops if l.vert == v)
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if (l1[uv].uv - l2[uv].uv).length > 1e-6:
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cont = False
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break
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if cont:
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pairs.append((f1.index, f2.index))
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signed = []
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for f in bm.faces:
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area = 0.0
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loops = f.loops
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for i in range(len(loops)):
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a = loops[i][uv].uv
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b = loops[(i + 1) % len(loops)][uv].uv
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area += a.x * b.y - b.x * a.y
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signed.append(area * 0.5)
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n = len(bm.faces)
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bm.free()
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return {"islands": count_islands(n, pairs),
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"fill": round(fill_ratio([abs(a) for a in signed]), 4),
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"flipped": round(flipped_fraction(signed), 4),
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"overlap": _overlap_fraction(obj)}
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def _overlap_fraction(obj):
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"""uv.select_overlap 统计重叠 UV 面占比；op 上下文不可用返回 None。"""
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import bpy
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bpy.context.scene.tool_settings.use_uv_select_sync = True
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.mode_set(mode='EDIT')
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bpy.ops.mesh.select_all(action='DESELECT')
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try:
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bpy.ops.uv.select_overlap()
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except RuntimeError:
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return None
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finally:
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bpy.ops.object.mode_set(mode='OBJECT')
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polys = obj.data.polygons
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if not len(polys):
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return 0.0
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return round(sum(1 for p in polys if p.select) / float(len(polys)), 4)
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_uvpm_failed = False # 进程内失败一次即不再重试（避免重复警告与启动开销）
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def _uvpm_enable():
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"""启用 UVPM4 扩展（幂等）。headless 下先补丁 GPU shader 创建——
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UVPM4 导入期为视口覆盖层建 shader，后台模式无 GPU 绘图会 SystemError；
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覆盖层仅交互用，pack 不受影响。引擎路径经注册表自动发现。"""
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import bpy
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import addon_utils
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if bpy.app.background:
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import gpu
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orig = gpu.shader.from_builtin
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if not getattr(orig, "_mt_safe", False):
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def _safe(*a, **k):
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try:
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return orig(*a, **k)
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except SystemError:
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return None
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_safe._mt_safe = True
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gpu.shader.from_builtin = _safe
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# default_set=True 才建 preferences.addons 条目（UVPM4 register 依赖）；
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# factory-startup 关闭偏好自动保存，不会写盘
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if addon_utils.enable(UVPM_EXT, default_set=True) is None:
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raise RuntimeError("扩展 %s 启用失败（未安装或版本不兼容）" % UVPM_EXT)
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def _uvpm_repack(obj, warnings):
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"""UVPM4 重排当前 UV 布局，成功返回 True；任何失败记警告返回 False，
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保底布局（pack_islands/smart_project）原样保留。"""
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global _uvpm_failed
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if _uvpm_failed:
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return False
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import bpy
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try:
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_uvpm_enable()
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p = bpy.context.scene.uvpm4_props.default_main_props
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p.pixel_margin_enable = True
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p.pixel_margin = UVPM_PIXEL_MARGIN
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p.pixel_margin_tex_size = UVPM_TEX_SIZE
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bpy.context.scene.tool_settings.use_uv_select_sync = True
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bpy.context.view_layer.objects.active = obj
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bpy.ops.object.mode_set(mode='EDIT')
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bpy.ops.mesh.select_all(action='SELECT')
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try:
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ret = bpy.ops.uvpackmaster4.pack(mode_id='pack.single_tile',
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pack_op_type='0')
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finally:
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bpy.ops.object.mode_set(mode='OBJECT')
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if 'FINISHED' not in ret:
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raise RuntimeError("pack 返回 %s" % sorted(ret))
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return True
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except Exception as e:
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_uvpm_failed = True
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warnings.append("UVPackmaster 排布不可用（%s），沿用内置 pack 布局" % e)
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return False
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def _do_unwrap(obj, mode, warnings, overlap_tol=UV_OVERLAP_TOL):
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"""按模式展开：seam 从 SEAM_ANGLE_DEG 起降序扫 SEAM_ANGLE_SWEEP，首个过门者即选并停扫
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——岛数随角度降单调增，故首个过门者已是过门候选里岛数最少的（pick_best_candidate 据此在
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候选集取岛数最少者，与早停一致；重跑分支为防御：早停下 best 恒为最后一档，通常不触发）；
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全失败退 smart。overlap_tol 覆盖重叠门限（翻转仍严格）。排布 UVPM4 增强，只在最终 UV
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上跑一次，失败保底内置 pack。返回 uv 指标 dict（含 mode）。"""
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if mode == "seam":
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angles = [SEAM_ANGLE_DEG] + list(SEAM_ANGLE_SWEEP)
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candidates = []
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for ang in angles:
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_unwrap_seam(obj, warnings, seam_angle_deg=ang)
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m = _collect_uv_metrics(obj)
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m["angle"] = ang
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candidates.append(m)
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if uv_gate_ok(m["flipped"], m["overlap"], overlap_tol):
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break # 该档已过门；更低角度只会更碎，无需再试
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best = pick_best_candidate(candidates, overlap_tol)
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if best is not None:
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if best["angle"] != candidates[-1]["angle"]:
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# 选中档不是最后跑的那档，重跑恢复其 UV（_unwrap_seam 会覆盖）
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_unwrap_seam(obj, warnings, seam_angle_deg=best["angle"])
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uvpm = _uvpm_repack(obj, warnings)
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m = _collect_uv_metrics(obj)
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m["mode"] = uvpm_mode_label("seam@%d" % int(best["angle"]), uvpm)
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return m
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detail = "、".join(
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"%d°(翻转%.1f%% 重叠%s)" % (
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int(c["angle"]), c["flipped"] * 100,
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"%.1f%%" % (c["overlap"] * 100) if c["overlap"] is not None else "未知")
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for c in candidates)
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warnings.append("所有 seam 角度均未过质量门（%s），回退 smart_project" % detail)
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mode = "smart_fallback"
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_unwrap_smart(obj)
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uvpm = _uvpm_repack(obj, warnings)
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m = _collect_uv_metrics(obj)
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m["mode"] = uvpm_mode_label(mode if mode == "smart_fallback" else "smart", uvpm)
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return m
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def _collect_uv_polygons(obj):
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"""提取每个面的 UV 多边形（归一化坐标）：[[[u,v], ...], ...]，供外部 PIL 绘图。
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无 UV 层返回空列表。"""
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import bmesh
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bm = bmesh.new()
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bm.from_mesh(obj.data)
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uv = bm.loops.layers.uv.active
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polys = []
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if uv is not None:
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for f in bm.faces:
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polys.append([[l[uv].uv.x, l[uv].uv.y] for l in f.loops])
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bm.free()
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return polys
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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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src, out_fbx, target = argv[0], argv[1], int(argv[2])
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unwrap_mode = argv[3] if len(argv) > 3 else "seam"
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overlap_tol = float(argv[4]) if len(argv) > 4 and argv[4] else UV_OVERLAP_TOL
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warnings = []
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bpy.ops.wm.read_factory_settings(use_empty=True)
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bpy.ops.import_scene.fbx(filepath=src)
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meshes = [o for o in bpy.data.objects if o.type == 'MESH']
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skipped = [o.name for o in bpy.data.objects if o.type != 'MESH']
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if skipped:
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warnings.append("忽略非 mesh 对象：%s（本工具只处理静态网格）" % ", ".join(skipped))
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if not meshes:
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print("MT_SUMMARY " + json.dumps({"error": "FBX 中没有 mesh"}, ensure_ascii=False))
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return
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obj = join_meshes(meshes)
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_triangulate(obj)
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orig = len(obj.data.polygons)
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cur = orig
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if cur <= target:
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warnings.append("当前 %d 面 <= 目标 %d，跳过减面" % (cur, target))
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else:
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# collapse 结果是近似值；未达容差时按新面数修正 ratio 再来，最多 MAX_RETRY 轮
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for _ in range(1 + MAX_RETRY):
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_decimate(obj, decimate_ratio(target, cur))
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_triangulate(obj) # collapse triangulate 后仍可能残留非三角面
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cur = len(obj.data.polygons)
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if within_tolerance(target, cur) or cur <= target:
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break
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# 重试用尽仍超差且偏多：记录警告，交由上层决定是否可接受
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if not within_tolerance(target, cur) and cur > target:
|
||
warnings.append("修正 %d 轮后仍超差：%d 面（目标 %d ±3%%）" % (MAX_RETRY, cur, target))
|
||
|
||
uv_info = _do_unwrap(obj, unwrap_mode, warnings, overlap_tol)
|
||
uv_png = os.path.splitext(os.path.abspath(out_fbx))[0] + "_uv.png"
|
||
uv_polys_json = os.path.splitext(os.path.abspath(out_fbx))[0] + "_uv.polys.json"
|
||
uv_preview = None
|
||
try:
|
||
polys = _collect_uv_polygons(obj)
|
||
os.makedirs(os.path.dirname(uv_polys_json), exist_ok=True)
|
||
with open(uv_polys_json, "w", encoding="utf-8") as fp:
|
||
json.dump(polys, fp)
|
||
uv_preview = uv_png # 目标 PNG；实际绘制由 model_decimate（系统 Python + PIL）完成
|
||
except Exception as e:
|
||
warnings.append("UV 几何导出失败（%s），跳过观察图" % e)
|
||
out_dir = os.path.dirname(os.path.abspath(out_fbx))
|
||
os.makedirs(out_dir, exist_ok=True)
|
||
# 仅导出合并后的对象；整场景导出会把 armature/empty 等非 mesh 带进 _low.fbx
|
||
bpy.ops.export_scene.fbx(filepath=out_fbx, use_selection=True,
|
||
path_mode='STRIP', embed_textures=False)
|
||
|
||
print("MT_SUMMARY " + json.dumps(
|
||
{"src": os.path.basename(src), "fbx": os.path.basename(out_fbx),
|
||
"tris_before": orig, "tris_after": cur, "target": target,
|
||
"uv": uv_info,
|
||
"uv_preview": uv_preview,
|
||
"uv_polys": uv_polys_json if uv_preview else None,
|
||
"warnings": warnings},
|
||
ensure_ascii=False))
|
||
|
||
|
||
if __name__ == "__main__" and "--" in sys.argv:
|
||
main()
|