Simplified mesh intersection logic (#221)

CHANGELOG.md

@@ -2,9 +2,17 @@
 
 ## Unreleased
 
+### Added
+
+- Add `Triangle::robust_scaled_normal` and `Triangle::robust_normal` as a more robust way to compute the triangles
+  normal for thin triangles that generally cause numerical instabilities.
+- Add `Triangle::angle_closest_to_90` to find the triangle’s vertex with an angle closest to 90 degree.
+- Add the `wavefront` feature that enables `TriMesh::to_obj_file` for exporting a mesh as an obj file.
+
 ### Modified
 
 - `TypedShape::Custom(u32)` is now `TypedShape::Custom(&dyn Shape)`.
+- Significantly improved the general stability of mesh/mesh intersection calculation.
 
 ## v0.16.1
 

assets/tests/bar.obj

@@ -0,0 +1,195 @@
+# Author: Camilo Talero
+# License: CC0
+v 0.467654 13.305400 -6.892637
+v -0.550473 -3.651697 6.193181
+v 0.451122 13.300038 -6.900873
+v -0.567006 -3.657059 6.184945
+v 0.436815 13.292733 -6.911451
+v -0.581312 -3.664363 6.174367
+v 0.425285 13.283769 -6.923967
+v -0.592842 -3.673329 6.161853
+v 0.416975 13.273486 -6.937937
+v -0.601152 -3.683610 6.147883
+v 0.412204 13.262284 -6.952824
+v -0.605924 -3.694813 6.132995
+v 0.411154 13.250590 -6.968058
+v -0.606973 -3.706506 6.117761
+v 0.413868 13.238854 -6.983053
+v -0.604259 -3.718241 6.102765
+v 0.420240 13.227530 -6.997232
+v -0.597888 -3.729566 6.088586
+v 0.430025 13.217050 -7.010054
+v -0.588102 -3.740046 6.075767
+v 0.442847 13.207818 -7.021019
+v -0.575280 -3.749279 6.064799
+v 0.458215 13.200187 -7.029711
+v -0.559913 -3.756910 6.056108
+v 0.475536 13.194451 -7.035795
+v -0.542591 -3.762644 6.050025
+v 0.494146 13.190835 -7.039036
+v -0.523982 -3.766263 6.046782
+v 0.513329 13.189469 -7.039310
+v -0.504798 -3.767626 6.046510
+v 0.532348 13.190415 -7.036608
+v -0.485779 -3.766682 6.049212
+v 0.550472 13.193629 -7.031031
+v -0.467655 -3.763467 6.054788
+v 0.567005 13.198991 -7.022795
+v -0.451122 -3.758105 6.063024
+v 0.581311 13.206296 -7.012217
+v -0.436816 -3.750801 6.073602
+v 0.592841 13.215261 -6.999702
+v -0.425286 -3.741835 6.086116
+v 0.601151 13.225543 -6.985735
+v -0.416976 -3.731554 6.100085
+v 0.605923 13.236745 -6.970846
+v -0.412204 -3.720351 6.114974
+v 0.606972 13.248439 -6.955610
+v -0.411155 -3.708658 6.130208
+v 0.604259 13.260175 -6.940615
+v -0.413868 -3.696923 6.145204
+v 0.597887 13.271499 -6.926435
+v -0.420240 -3.685598 6.159383
+v 0.588102 13.281980 -6.913616
+v -0.430025 -3.675117 6.172202
+v 0.575279 13.291211 -6.902651
+v -0.442848 -3.665884 6.183169
+v 0.559912 13.298842 -6.893957
+v -0.458215 -3.658254 6.191861
+v 0.542591 13.304578 -6.887875
+v -0.475536 -3.652520 6.197946
+v 0.523981 13.308194 -6.884634
+v -0.494146 -3.648901 6.201186
+v 0.504798 13.309560 -6.884359
+v -0.513329 -3.647538 6.201461
+v 0.485779 13.308614 -6.887062
+v -0.532348 -3.648482 6.198758
+# 64 vertices, 0 vertices normals
+
+f 3 2 1
+f 6 3 5
+f 8 5 7
+f 10 7 9
+f 11 10 9
+f 13 12 11
+f 15 14 13
+f 17 16 15
+f 19 18 17
+f 21 20 19
+f 24 21 23
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+f 28 25 27
+f 29 28 27
+f 31 30 29
+f 33 32 31
+f 35 34 33
+f 37 36 35
+f 40 37 39
+f 42 39 41
+f 44 41 43
+f 45 44 43
+f 48 45 47
+f 50 47 49
+f 52 49 51
+f 54 51 53
+f 56 53 55
+f 57 56 55
+f 60 57 59
+f 62 59 61
+f 14 22 6
+f 64 61 63
+f 2 63 1
+f 63 55 31
+f 4 2 3
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+f 46 45 48
+f 48 47 50
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+f 58 56 57
+f 58 57 60
+f 60 59 62
+f 4 6 62
+f 2 4 62
+f 64 2 62
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+f 56 58 62
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+f 52 54 50
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+f 42 44 38
+f 40 42 38
+f 36 38 30
+f 34 36 30
+f 32 34 30
+f 28 30 26
+f 24 26 22
+f 20 22 14
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+f 50 54 38
+f 46 50 38
+f 26 30 22
+f 62 6 38
+f 54 62 38
+f 30 38 6
+f 22 30 6
+f 62 61 64
+f 64 63 2
+f 1 63 3
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+f 9 7 15
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+f 17 15 19
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+f 27 23 15
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+f 43 39 31
+f 47 43 31
+f 59 55 63
+f 7 63 31
+f 15 7 31
+f 55 47 31
+# 124 faces, 0 coords texture
+
+# End of File