Render Shapely multipolygon as a 3D prism and export in gltf2
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from shapely import wkb | |
from shapely.ops import triangulate | |
from shapely.geometry import LineString | |
import trimesh | |
# Hol-y building https://www.openstreetmap.org/relation/3868363 | |
wkb_holes = bytes.fromhex( | |
""" | |
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41BBA067EAA3D836414EC6A5B2124A5A411400000019C01806C0D8364154B513D6134A5A4169A46 | |
58FC7D83641CEAF6583184A5A413B915CE6D0D83641F6A5548C1E4A5A41048E17ECD6D83641120D | |
7FEF1D4A5A417FA89FD8D7D83641314AC67A1E4A5A41C897F2ACDBD836418FE275181E4A5A41DF3 | |
4AACEDAD8364130A72E8D1D4A5A411886BBFDE3D8364136A81FAA1C4A5A418224AA7BF1D83641E3 | |
BA7D471B4A5A418CCDF16BE8D836419EFE7452154A5A41244271F9E0D836411ECCC094104A5A41C | |
4470C08CAD836416570C2D5124A5A412CA7687CC9D83641AF66267F124A5A41A0D88CEBC9D83641 | |
61CD9D74124A5A4185433721C9D83641701BE5FA114A5A41E5A8DB7CC4D83641F4055280124A5A4 | |
1A89CA43EC5D836418C9D30F4124A5A415EC821CDC5D83641AFE7CDE3124A5A414042062EC6D836 | |
41A514E736134A5A4119C01806C0D8364154B513D6134A5A410D00000083A5FBE4D9D8364106EE4 | |
D6C244A5A41AB337F44E3D836412B56484C2A4A5A416366D4A6E6D83641505B407F2C4A5A414BB8 | |
C8E9E3D83641482BD1C72C4A5A4132258D8FE5D83641CB5297ED2D4A5A4154A8043BE7D836415AE | |
94EC92D4A5A419E814510E7D8364193A1E0AA2D4A5A41C842C541FBD8364165339FBA2B4A5A4174 | |
E0CA4209D936418B57A5552A4A5A417D9F243204D9364177EB2F21274A5A41A5CE87C1FAD836411 | |
164191E214A5A41A7785935EDD83641FE96016E224A5A4183A5FBE4D9D8364106EE4D6C244A5A41 | |
1800000061C8986AF7D836418A2F42570E4A5A41C858D740FFD836416BAEC40C134A5A41A8085C6 | |
708D936416D4EB81C194A5A419E7FA23D16D93641A42942BB174A5A412D7240751FD936410CD884 | |
D3164A5A4151E67DF51FD936413E707225174A5A414AFD19781FD93641310BFB2F174A5A418A01E | |
F5E20D93641424BBFB7174A5A41AE8B3EDE24D93641E423323F174A5A4124AE282224D936413668 | |
BFB2164A5A41B07C04B323D936416AA273BE164A5A411EC0064123D936413067B774164A5A41E7B | |
CC14629D936413B7590DC154A5A410029970620D93641B604E0E90F4A5A41CCCF238018D93641A0 | |
7A1B170B4A5A4186C25C5512D93641211C68A90B4A5A41634E1FD511D93641A9034F560B4A5A41B | |
AF4694112D93641C66CC64B0B4A5A416B2D078B11D936413F7639D30A4A5A413ADB6BD80CD93641 | |
B9E874500B4A5A41FDCE349A0DD936412827FCC10B4A5A41B3FAB1280ED9364126521CB50B4A5A4 | |
169262FB70ED93641A46B35080C4A5A4161C8986AF7D836418A2F42570E4A5A41170000005C6A79 | |
BB11D93641F731C5E11E4A5A4154A1A30416D936414730B2A4214A5A41DA815DB414D93641A54BA | |
3C6214A5A41E944EB8314D93641729086A3214A5A41E7478F7712D936413D0863E0214A5A41E260 | |
456A14D93641C0E6020C234A5A416A4D955116D93641850C52D0224A5A417810232116D9364144A | |
F66B5224A5A41B919B66B17D936415D13C78E224A5A41B92A0A071BD9364152C92CE0244A5A41F9 | |
44F1EC1FD93641D7181F11284A5A413E791EB22DD93641680868C9264A5A41B40963F140D936413 | |
5A9AFE3244A5A41E057CAC340D936414ECA15C4244A5A4103D6830B42D93641702BD3A6244A5A41 | |
F412F63B42D93641C5E94CD3244A5A4107CE21B443D9364126EBD8AD244A5A412F24EBDD41D9364 | |
13C1C1388234A5A419386EB453FD93641A2D746C7234A5A41C4AC62FA3BD93641314EE9B3214A5A | |
41D04B2E2332D936412D9EC29B1B4A5A419ABA00671FD93641D267D78A1D4A5A415C6A79BB11D93 | |
641F731C5E11E4A5A41 | |
""".replace( | |
"\n", "" | |
) | |
) | |
# wkb_holes = bytes.fromhex('0106000000010000000103000000020000000500000061CD67C002DB364196BAB7A7D5495A41E226F95343DB3641D8685634CF495A4114B60CA053DB364162272C1AD9495A417DB5472313DB3641407DD9E8DF495A4161CD67C002DB364196BAB7A7D5495A4105000000CCB922731FDB3641B31F738FD6495A4150D53A4C27DB36410FA64F55DB495A41446C0FE939DB3641957DED6AD9495A41BF50F70F32DB36418F4311A5D4495A41CCB922731FDB3641B31F738FD6495A41') | |
s = wkb.loads(wkb_holes) | |
# apply polygon triangulation to have triangles | |
# note that if there are holes they are covered too | |
internal_triangles = [tri for tri in triangulate(s) if tri.within(s)] | |
# render the internal and external triangles to show the structure | |
import shapely.geometry | |
mul = shapely.geometry.MultiPolygon(internal_triangles) | |
with open("check_internal.svg", "w") as fw: | |
fw.write(mul._repr_svg_()) | |
mul_holes = shapely.geometry.MultiPolygon( | |
[tri for tri in triangulate(s) if not tri.within(s)] | |
) | |
with open("check_external.svg", "w") as fw: | |
fw.write(mul_holes._repr_svg_()) | |
with open("check_all_triangles.svg", "w") as fw: | |
fw.write(shapely.geometry.MultiPolygon(triangulate(s))._repr_svg_()) | |
# validate it with trimesh | |
# it will take care of merging overlapping vertices | |
vertices = [] | |
faces = [] | |
HEIGHT = 100.0 | |
dbg_int_segments = [] | |
dbg_ext_segments = [] | |
for tri_num, tri in enumerate(internal_triangles): | |
# it's 4 coordinates, the last is identical to the first to form a circuit | |
for x, y in tri.exterior.coords[:-1]: | |
vertices.append([x, y, 0.0]) | |
for x, y in tri.exterior.coords[:-1]: | |
vertices.append([x, y, HEIGHT]) | |
# now 6 points have been added | |
idx = tri_num * 6 | |
# bottom and top faces of the prism, use as is | |
faces.append([idx + 2, idx + 1, idx]) | |
faces.append([idx + 3, idx + 4, idx + 5]) | |
# now for the 3 lateral faces check that they do not fall inside the base | |
# before adding them, or we'd have an invalid topology | |
for i1, i2 in ((0, 1), (1, 2), (2, 0)): | |
if LineString([tri.exterior.coords[i1], tri.exterior.coords[i2]]).within(s): | |
dbg_int_segments.append( | |
LineString([tri.exterior.coords[i1], tri.exterior.coords[i2]]) | |
) | |
continue | |
dbg_ext_segments.append( | |
LineString([tri.exterior.coords[i1], tri.exterior.coords[i2]]) | |
) | |
# add the two triangles making up the exterior face | |
# there are 2 equivalent ways to split it, just use one | |
faces.append([idx + i1, idx + i2, idx + i1 + 3]) | |
faces.append([idx + i2, idx + i2 + 3, idx + i1 + 3]) | |
with open("check_external_segments.svg", "w") as fw: | |
fw.write(shapely.geometry.MultiLineString(dbg_ext_segments)._repr_svg_()) | |
with open("check_internal_segments.svg", "w") as fw: | |
fw.write(shapely.geometry.MultiLineString(dbg_int_segments)._repr_svg_()) | |
mesh = trimesh.Trimesh( | |
vertices=vertices, | |
faces=faces, | |
) | |
# requires networkx installed | |
# trimesh.repair.fix_inversion(mesh) | |
# trimesh.repair.fix_winding(mesh) | |
# trimesh.repair.fix_normals(mesh, multibody=True) | |
# mesh.fill_holes() | |
mesh.export("mesh_topo.ply") | |
mesh.export("mesh_topo.glb") | |
print(mesh.euler_number) | |
# requires pyglet installed | |
mesh.show() |
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