CGAL users discussion list

[Rob Pieké <>]

Sadly, I'm not sure what more to say. I'm able to convert the geometry 
to Nef-land, but the boolean difference generates a non-2-manifold Nef 
result that I can't convert back to polygons.

Neither geometry is convex, but they're both water-tight and do not 
self-intersect. In total, the two objects are comprised of ~250 triangles.

Even if I use the nef_3_filtered demo application, I get an assertion error.

nef_3_filtered loadoff crack.off loadoff obj.off diff saveoff diff.off

CGAL error: assertion violation!
Expr: itl != it->second.end()
File: ../../include/CGAL/Nef_3/SNC_external_structure.h
Line: 1096
Explanation:
terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: itl != it->second.end()
File: ../../include/CGAL/Nef_3/SNC_external_structure.h
Line: 1096
Abort

I'm attempting to attach the offending .off files (not sure if the list 
accepts attachments or not).

Many thanks for any advice!
OFF
48 92 0

# vertices
11.1346 3.16066 2.47431
11.1076 3.15296 2.45198
11.127 3.24617 2.45397
11.1 3.23847 2.43164
11.0406 4.22279 2.22174
11.0136 4.2151 2.19941
11.0323 4.31624 2.19951
11.0053 4.30855 2.17718
10.9459 5.29287 1.96728
10.9189 5.28517 1.94495
10.94 5.35945 1.95144
10.913 5.35175 1.92911
9.06654 5.70367 4.09605
9.03956 5.69597 4.07372
9.07243 5.63709 4.11188
9.04545 5.62939 4.08955
9.15883 4.66046 4.34412
9.13186 4.65277 4.32179
9.1671 4.56701 4.36634
9.14013 4.55932 4.34401
9.25351 3.59039 4.59858
9.22653 3.58269 4.57625
9.26108 3.50488 4.61891
9.2341 3.49718 4.59658
12.0013 5.66225 2.82994
9.85178 5.04895 1.05061
7.97829 5.39317 3.19522
10.1278 6.00647 4.97455
7.98419 5.32659 3.21105
9.85767 4.98237 1.06645
10.1337 5.93989 4.99038
12.0072 5.59567 2.84578
10.3223 3.80768 5.49741
8.17283 3.19438 3.71809
10.0463 2.85016 1.57348
12.1958 3.46346 3.35281
8.16527 3.27989 3.69775
10.0388 2.93567 1.55314
12.1883 3.54897 3.33247
10.3148 3.89319 5.47708
8.07886 4.25652 3.46551
9.95234 3.9123 1.32091
8.07059 4.34997 3.44329
9.94408 4.00575 1.29869
10.2284 4.86981 5.24484
12.1019 4.52559 3.10023
12.0936 4.61904 3.07801
10.2201 4.96326 5.22262

# faces
3 2 1 0
3 3 1 2
3 4 3 2
3 5 3 4
3 6 5 4
3 7 5 6
3 8 7 6
3 9 7 8
3 10 9 8
3 11 9 10
3 27 25 24
3 26 25 27
3 14 13 12
3 15 13 14
3 16 15 14
3 17 15 16
3 18 17 16
3 19 17 18
3 20 19 18
3 21 19 20
3 22 21 20
3 23 21 22
3 35 33 32
3 34 33 35
3 37 33 34
3 36 33 37
3 5 21 3
3 19 21 5
3 43 40 41
3 42 40 43
3 9 17 7
3 15 17 9
3 25 28 29
3 26 28 25
3 39 35 32
3 38 35 39
3 18 2 20
3 4 2 18
3 47 45 44
3 46 45 47
3 14 6 16
3 8 6 14
3 27 31 30
3 24 31 27
3 11 24 25
3 24 11 10
3 12 26 27
3 26 12 13
3 29 15 9
3 28 15 29
3 28 13 15
3 26 13 28
3 25 9 11
3 29 9 25
3 30 8 14
3 31 8 30
3 31 10 8
3 24 10 31
3 27 14 12
3 30 14 27
3 23 32 33
3 32 23 22
3 0 34 35
3 34 0 1
3 33 21 23
3 36 21 33
3 36 3 21
3 37 3 36
3 37 1 3
3 34 1 37
3 35 2 0
3 38 2 35
3 38 20 2
3 39 20 38
3 39 22 20
3 32 22 39
3 41 19 5
3 40 19 41
3 40 17 19
3 42 17 40
3 42 7 17
3 43 7 42
3 43 5 7
3 41 5 43
3 44 4 18
3 45 4 44
3 45 6 4
3 46 6 45
3 46 16 6
3 47 16 46
3 47 18 16
3 44 18 47
OFF
74 144 0

# vertices
9.44578 -5 3.01268
9.41455 -5 3.77741
9.93321 -5 4.34024
10.6979 -5 4.37147
11.2608 -5 3.85281
11.292 -5 3.08808
10.7733 -5 2.52525
10.0086 -5 2.49402
9.44578 -5.72205e-06 3.01268
9.41455 -5.72205e-06 3.77741
9.93321 -5.72205e-06 4.34024
10.6979 -5.72205e-06 4.37147
11.2608 -5.72205e-06 3.85281
11.292 -5.72205e-06 3.08808
10.7733 -5.72205e-06 2.52525
10.0086 -5.72205e-06 2.49402
9.63388 0.420709 3.09975
9.60913 0.420709 3.70596
10.0203 0.420709 4.15213
10.6265 0.420709 4.17689
11.0727 0.420709 3.76574
11.0974 0.420709 3.15952
10.6863 0.420709 2.71335
10.0801 0.420709 2.68859
9.92552 1.4515 3.11996
9.91254 1.4515 3.43764
10.128 1.4515 3.67144
10.4457 1.4515 3.68442
10.6795 1.4515 3.46896
10.6925 1.4515 3.15128
10.477 1.4515 2.91747
10.1593 1.4515 2.9045
10.1166 5 3.30036
10.1088 5 3.49129
10.2383 5 3.63182
10.4292 5 3.63961
10.5698 5 3.51012
10.5776 5 3.31918
10.4481 5 3.17866
10.2571 5 3.17086
9.99889 8.5485 3.31981
9.98592 8.5485 3.63749
10.2014 8.5485 3.87129
10.5191 8.5485 3.88427
10.7529 8.5485 3.66881
10.7658 8.5485 3.35113
10.5504 8.5485 3.11732
10.2327 8.5485 3.10435
9.63388 9.57929 3.09975
9.60913 9.57929 3.70596
10.0203 9.57929 4.15213
10.6265 9.57929 4.17689
11.0727 9.57929 3.76574
11.0974 9.57929 3.15952
10.6863 9.57929 2.71335
10.0801 9.57929 2.68859
9.44578 10 3.01268
9.41455 10 3.77741
9.93321 10 4.34024
10.6979 10 4.37147
11.2608 10 3.85281
11.292 10 3.08808
10.7733 10 2.52525
10.0086 10 2.49402
9.44578 15 3.01268
9.41455 15 3.77741
9.93321 15 4.34024
10.6979 15 4.37147
11.2608 15 3.85281
11.292 15 3.08808
10.7733 15 2.52525
10.0086 15 2.49402
10.3533 -5 3.43274
10.3533 15 3.43274

# faces
3 8 1 0
3 9 1 8
3 9 2 1
3 10 2 9
3 10 3 2
3 11 3 10
3 11 4 3
3 12 4 11
3 12 5 4
3 13 5 12
3 13 6 5
3 14 6 13
3 14 7 6
3 15 7 14
3 15 0 7
3 8 0 15
3 16 9 8
3 17 9 16
3 17 10 9
3 18 10 17
3 18 11 10
3 19 11 18
3 19 12 11
3 20 12 19
3 20 13 12
3 21 13 20
3 21 14 13
3 22 14 21
3 22 15 14
3 23 15 22
3 23 8 15
3 16 8 23
3 16 25 17
3 24 25 16
3 17 26 18
3 25 26 17
3 18 27 19
3 26 27 18
3 27 20 19
3 28 20 27
3 28 21 20
3 29 21 28
3 29 22 21
3 30 22 29
3 30 23 22
3 31 23 30
3 23 24 16
3 31 24 23
3 32 25 24
3 33 25 32
3 33 26 25
3 34 26 33
3 34 27 26
3 35 27 34
3 27 36 28
3 35 36 27
3 28 37 29
3 36 37 28
3 29 38 30
3 37 38 29
3 30 39 31
3 38 39 30
3 39 24 31
3 32 24 39
3 40 33 32
3 41 33 40
3 41 34 33
3 42 34 41
3 42 35 34
3 43 35 42
3 35 44 36
3 43 44 35
3 36 45 37
3 44 45 36
3 37 46 38
3 45 46 37
3 38 47 39
3 46 47 38
3 47 32 39
3 40 32 47
3 40 49 41
3 48 49 40
3 41 50 42
3 49 50 41
3 42 51 43
3 50 51 42
3 51 44 43
3 52 44 51
3 52 45 44
3 53 45 52
3 53 46 45
3 54 46 53
3 54 47 46
3 55 47 54
3 47 48 40
3 55 48 47
3 56 49 48
3 57 49 56
3 57 50 49
3 58 50 57
3 58 51 50
3 59 51 58
3 59 52 51
3 60 52 59
3 60 53 52
3 61 53 60
3 61 54 53
3 62 54 61
3 62 55 54
3 63 55 62
3 63 48 55
3 56 48 63
3 64 57 56
3 65 57 64
3 65 58 57
3 66 58 65
3 66 59 58
3 67 59 66
3 67 60 59
3 68 60 67
3 68 61 60
3 69 61 68
3 69 62 61
3 70 62 69
3 70 63 62
3 71 63 70
3 71 56 63
3 64 56 71
3 72 0 1
3 72 1 2
3 72 2 3
3 72 3 4
3 72 4 5
3 72 5 6
3 72 6 7
3 72 7 0
3 73 65 64
3 73 66 65
3 73 67 66
3 73 68 67
3 73 69 68
3 73 70 69
3 73 71 70
3 73 64 71