compas
compas copied to clipboard
Published
20 hours ago •
compas-dev
compas-dev
polyline offset bug or extreme edge case ?
Describe the bug Disclaimer : This might not be a bug, but does lead to unexpected behavior. I'm personally comparing the functionality of this function with grasshopper's offset curve.
Background: I'm working a lot with polylines originating from mesh - plane slices (using slice_mesh from compas.cgal (trimesh). In my process I wish to offset these polylines (derived from the slice_mesh command) multiple times. As trimesh only works with triangular meshes, I convert my input mesh from quad to tri-mesh. Occasionally the input mesh has an area where 'curvature' is very small, e.g. almost straight, this combined with the slice plane intersecting very close to (but not on) a mesh vertex creates polylines with points very close to one another. These segments area also 'almost' parallel. For a typical scenario of my use case, the polylines are always open and have relatively large angles between segments i.e. not sharp corners.
To me it seems that the root of the problem lies in floating point arithmetic.
Alternatively there are ways around this i.e. clean[rebuild] the polyline however not available in compas, or sort through polyline points after offsetting, using quadmeshes.. I have been struggling with this for a while and have decided that it is an interesting problem worth solving...
If this post is not sufficient I can gladly talk via zoom etc..
To Reproduce
- Use either .GH file to visualize the issue.. from internalized data, and to compare to GH behavior..
- attached .py script to reproduce offsets and compare.
Expected behavior Expected behavior is that of Grasshopper's offset polyline curve.
Screenshots see attached polyline offset issue.zip
Desktop (please complete the following information):
- OS: Windows
- Python version 3.9.10
- Python package manager conda:
#
# Name Version Build Channel
appdirs 1.4.4 pyh9f0ad1d_0 conda-forge
argh 0.26.2 pyh9f0ad1d_1002 conda-forge
attrs 21.4.0 pyhd8ed1ab_0 conda-forge
autobahn 22.2.2 pyhd8ed1ab_0 conda-forge
automat 20.2.0 py_0 conda-forge
autopep8 1.6.0 pyhd8ed1ab_1 conda-forge
bcrypt 3.2.0 py39hb82d6ee_2 conda-forge
boost-cpp 1.74.0 h9f4b32c_7 conda-forge
brotli 1.0.9 h8ffe710_6 conda-forge
brotli-bin 1.0.9 h8ffe710_6 conda-forge
[polyline offset issue.zip](https://github.com/compas-dev/compas/files/8315579/polyline.offset.issue.zip)
bullet-cpp 3.21 h2e25243_1 conda-forge
bzip2 1.0.8 h8ffe710_4 conda-forge
ca-certificates 2021.10.8 h5b45459_0 conda-forge
certifi 2021.10.8 py39hcbf5309_1 conda-forge
cffi 1.15.0 py39h0878f49_0 conda-forge
cgal-cpp 5.4 h3c2f9b9_0 conda-forge
compas 1.14.1 py39hcbf5309_0 conda-forge
compas_cgal 0.4.0 py39h856da1f_0 conda-forge
compas_fab 0.22.0 py39hcbf5309_1 conda-forge
compas_rrc 1.1.0 pyhd8ed1ab_0 conda-forge
compas_view2 0.4.4 py39hcbf5309_0 conda-forge
constantly 15.1.0 py_0 conda-forge
contextlib2 0.5.5 py_2 conda-forge
cryptography 36.0.1 py39h7bc7c5c_0 conda-forge
cycler 0.11.0 pyhd8ed1ab_0 conda-forge
cython 0.29.28 py39h415ef7b_0 conda-forge
eigen 3.3.9 h2d74725_1 conda-forge
ezdxf 0.17.2 py39h2e07f2f_0 conda-forge
flake8 4.0.1 pyhd8ed1ab_2 conda-forge
fonttools 4.30.0 py39hb82d6ee_0 conda-forge
freeglut 3.2.2 h0e60522_1 conda-forge
freetype 2.10.4 h546665d_1 conda-forge
freetype-py 2.2.0 pyh9f0ad1d_0 conda-forge
hyperlink 21.0.0 pyhd3deb0d_0 conda-forge
icu 68.2 h0e60522_0 conda-forge
idna 3.3 pyhd8ed1ab_0 conda-forge
imageio 2.16.1 pyhcf75d05_0 conda-forge
importlib-metadata 4.11.3 py39hcbf5309_0 conda-forge
importlib_resources 5.4.0 pyhd8ed1ab_0 conda-forge
incremental 21.3.0 pyhd8ed1ab_0 conda-forge
intel-openmp 2022.0.0 h57928b3_3663 conda-forge
jbig 2.1 h8d14728_2003 conda-forge
jpeg 9e h8ffe710_0 conda-forge
jsonschema 4.4.0 pyhd8ed1ab_0 conda-forge
kiwisolver 1.4.0 py39h2e07f2f_0 conda-forge
laspy 2.1.2 pyh8a188c0_0 conda-forge
lcms2 2.12 h2a16943_0 conda-forge
lerc 3.0 h0e60522_0 conda-forge
libblas 3.9.0 13_win64_mkl conda-forge
libbrotlicommon 1.0.9 h8ffe710_6 conda-forge
libbrotlidec 1.0.9 h8ffe710_6 conda-forge
libbrotlienc 1.0.9 h8ffe710_6 conda-forge
libcblas 3.9.0 13_win64_mkl conda-forge
libclang 11.1.0 default_h5c34c98_1 conda-forge
libdeflate 1.10 h8ffe710_0 conda-forge
libffi 3.4.2 h8ffe710_5 conda-forge
libiconv 1.16 he774522_0 conda-forge
liblapack 3.9.0 13_win64_mkl conda-forge
libpng 1.6.37 h1d00b33_2 conda-forge
libtiff 4.3.0 hc4061b1_3 conda-forge
libwebp 1.2.2 h57928b3_0 conda-forge
libwebp-base 1.2.2 h8ffe710_1 conda-forge
libxcb 1.13 hcd874cb_1004 conda-forge
libxml2 2.9.12 hf5bbc77_1 conda-forge
libxslt 1.1.33 h65864e5_3 conda-forge
libzlib 1.2.11 h8ffe710_1013 conda-forge
llvmlite 0.38.0 py39ha0cd8c8_0 conda-forge
lz4-c 1.9.3 h8ffe710_1 conda-forge
m2w64-gcc-libgfortran 5.3.0 6 conda-forge
m2w64-gcc-libs 5.3.0 7 conda-forge
m2w64-gcc-libs-core 5.3.0 7 conda-forge
m2w64-gmp 6.1.0 2 conda-forge
m2w64-libwinpthread-git 5.0.0.4634.697f757 2 conda-forge
matplotlib-base 3.5.1 py39h581301d_0 conda-forge
mccabe 0.6.1 py_1 conda-forge
mesh-mould 0.1.0 dev_0 <develop>
mkl 2022.0.0 h0e2418a_796 conda-forge
mpfr 4.1.0 h8d14728_1 conda-forge
mpir 3.0.0 he025d50_1002 conda-forge
mpmath 1.2.1 pyhd8ed1ab_0 conda-forge
msys2-conda-epoch 20160418 1 conda-forge
munkres 1.1.4 pyh9f0ad1d_0 conda-forge
networkx 2.7.1 pyhd8ed1ab_0 conda-forge
nptyping 1.4.4 pyhd8ed1ab_0 conda-forge
numba 0.55.1 py39hb8cd55e_0 conda-forge
numpy 1.21.5 py39h6331f09_0 conda-forge
openjpeg 2.4.0 hb211442_1 conda-forge
openssl 1.1.1l h8ffe710_0 conda-forge
packaging 21.3 pyhd8ed1ab_0 conda-forge
pandas 1.4.1 py39h2e25243_0 conda-forge
pillow 9.0.1 py39ha53f419_2 conda-forge
pip 22.0.4 pyhd8ed1ab_0 conda-forge
planarity 3.0.0.5 hfa6e2cd_1002 conda-forge
pthread-stubs 0.4 hcd874cb_1001 conda-forge
pyasn1 0.4.8 py_0 conda-forge
pyasn1-modules 0.2.7 py_0 conda-forge
pybullet 3.21 py39h2e25243_1 conda-forge
pycodestyle 2.8.0 pyhd8ed1ab_0 conda-forge
pycollada 0.7.2 pyhd8ed1ab_0 conda-forge
pycparser 2.21 pyhd8ed1ab_0 conda-forge
pyflakes 2.4.0 pyhd8ed1ab_0 conda-forge
pyopengl 3.1.6 pyh6c4a22f_0 conda-forge
pyopenssl 22.0.0 pyhd8ed1ab_0 conda-forge
pyparsing 3.0.7 pyhd8ed1ab_0 conda-forge
pyrsistent 0.18.1 py39hb82d6ee_0 conda-forge
pyserial 3.5 pyhd8ed1ab_0 conda-forge
pyside2 5.13.2 py39hc084194_4 conda-forge
python 3.9.10 h9a09f29_2_cpython conda-forge
python-dateutil 2.8.2 pyhd8ed1ab_0 conda-forge
python-planarity 0.4.1 py39hb82d6ee_6 conda-forge
python_abi 3.9 2_cp39 conda-forge
pytz 2021.3 pyhd8ed1ab_0 conda-forge
pywin32 303 py39hb82d6ee_0 conda-forge
pyyaml 6.0 py39hb82d6ee_3 conda-forge
qt 5.12.9 h5909a2a_4 conda-forge
roslibpy 1.3.0 pyhd8ed1ab_0 conda-forge
schema 0.7.5 pyhd8ed1ab_0 conda-forge
scipy 1.8.0 py39hc0c34ad_1 conda-forge
service_identity 18.1.0 py_0 conda-forge
setuptools 60.10.0 py39hcbf5309_0 conda-forge
shapely 1.8.1.post1 pypi_0 pypi
six 1.16.0 pyh6c4a22f_0 conda-forge
sqlite 3.37.1 h8ffe710_0 conda-forge
sympy 1.10 py39hcbf5309_0 conda-forge
tbb 2021.5.0 h2d74725_0 conda-forge
tk 8.6.12 h8ffe710_0 conda-forge
toml 0.10.2 pyhd8ed1ab_0 conda-forge
trimesh 3.10.5 pypi_0 pypi
twisted 22.2.0 py39hb82d6ee_0 conda-forge
twisted-iocpsupport 1.0.2 py39hb82d6ee_1 conda-forge
txaio 21.2.1 pyhd8ed1ab_0 conda-forge
typing-extensions 4.1.1 hd8ed1ab_0 conda-forge
typing_extensions 4.1.1 pyha770c72_0 conda-forge
typish 1.9.3 pyhd8ed1ab_0 conda-forge
tzdata 2022a h191b570_0 conda-forge
ucrt 10.0.20348.0 h57928b3_0 conda-forge
unicodedata2 14.0.0 py39hb82d6ee_0 conda-forge
vc 14.2 hb210afc_6 conda-forge
vs2015_runtime 14.29.30037 h902a5da_6 conda-forge
watchdog 2.1.6 py39hcbf5309_1 conda-forge
wheel 0.37.1 pyhd8ed1ab_0 conda-forge
xorg-libxau 1.0.9 hcd874cb_0 conda-forge
xorg-libxdmcp 1.1.3 hcd874cb_0 conda-forge
xz 5.2.5 h62dcd97_1 conda-forge
yaml 0.2.5 h8ffe710_2 conda-forge
zipp 3.7.0 pyhd8ed1ab_1 conda-forge
zlib 1.2.11 h8ffe710_1013 conda-forge
zope.interface 5.4.0 py39hb82d6ee_1 conda-forge
zstd 1.5.2 h6255e5f_0 conda-forge```
