69 lines
2.8 KiB
Python
69 lines
2.8 KiB
Python
"""Check an exported stand with Blender's independent triangle BVH.
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blender --background --python-exit-code 1 --python script/inspect_stand.py -- stand.3mf report.json
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"""
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import json
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import sys
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import zipfile
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import xml.etree.ElementTree as ET
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from mathutils import Vector
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from mathutils.bvhtree import BVHTree
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source, output = sys.argv[sys.argv.index("--") + 1:]
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with zipfile.ZipFile(source) as package:
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root = ET.fromstring(package.read("3D/3dmodel.model"))
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ns = {"m": "http://schemas.microsoft.com/3dmanufacturing/core/2015/02"}
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meshes = root.findall("m:resources/m:object/m:mesh", ns)
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assert len(meshes) == 1, "Stand must contain exactly one mesh"
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mesh = meshes[0]
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vertices = [Vector(tuple(float(v.attrib[a]) for a in ("x", "y", "z")))
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for v in mesh.findall("m:vertices/m:vertex", ns)]
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faces = [tuple(int(t.attrib[a]) for a in ("v1", "v2", "v3"))
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for t in mesh.findall("m:triangles/m:triangle", ns)]
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edges = {}
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volume = 0.0
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flat_area = 0.0
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minimum_area = float("inf")
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for i, face in enumerate(faces):
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a, b, c = (vertices[j] for j in face)
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normal = (b-a).cross(c-a)
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area = normal.length / 2
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minimum_area = min(minimum_area, area)
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volume += a.dot(normal) / 6
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if max(abs(p.z) for p in (a, b, c)) < 1e-6:
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flat_area += area
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for j in range(3):
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u, v = face[j], face[(j+1) % 3]
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edges.setdefault(tuple(sorted((u, v))), []).append((i, u < v))
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assert all(len(uses) == 2 and uses[0][1] != uses[1][1] for uses in edges.values()), "Open edges or inconsistent winding"
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adjacency = [[] for _ in faces]
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for uses in edges.values():
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a, b = uses[0][0], uses[1][0]
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adjacency[a].append(b)
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adjacency[b].append(a)
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seen = {0}
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queue = [0]
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for face in queue:
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for other in adjacency[face]:
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if other not in seen:
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seen.add(other)
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queue.append(other)
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assert len(seen) == len(faces), "Disconnected shells"
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assert volume > 0 and minimum_area > 1e-10 and flat_area > 0
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tree = BVHTree.FromPolygons(vertices, faces, all_triangles=True, epsilon=0.0)
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intersections = []
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for a, b in tree.overlap(tree):
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if a >= b or set(faces[a]).intersection(faces[b]):
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continue
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intersections.append((a, b))
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report = {"vertices": len(vertices), "triangles": len(faces), "connected_components": 1,
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"watertight_consistent_winding": True, "signed_volume_mm3": volume,
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"table_contact_area_mm2": flat_area, "minimum_triangle_area_mm2": minimum_area,
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"nonadjacent_triangle_intersections": len(intersections), "intersection_examples": intersections[:10],
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"slicer_validation": "This script checks the mesh only; consult separate slicer results when available."}
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with open(output, "w") as stream:
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json.dump(report, stream, indent=2)
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print(json.dumps(report, indent=2))
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assert not intersections, "Nonadjacent triangles intersect"
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