Handling arcs vs? Beziers curves in paths

[PetitPhoenix]

Hello,

I use trimesh to generate STLs from various SVGs and it works great. My repository is generating tags based on various fonts and in the tag svg, I have arcs. When creating a mesh from this path, the one that has arcs is not watertight and has no volume:

shape_svg = trimesh.load_path(r'./inputs/shape.svg')
shape_svg.fill_gaps()
shape_mesh = shape_svg.extrude(3)

shape_ink_svg = trimesh.load_path(r'./inputs/shape_ink.svg')
shape_ink_mesh = shape_ink_svg.extrude(3)

In order to get the second one, I opened the first one in Inkscape and saved after changing the arcs in Bezier curves.

Wondering of there were limitations due to use in arc in paths or any special things to prepare my inputs.

Several parameters are very similar except the lenght:

Comparison:
bounds:
[[-17.49998212   0.        ]
 [ 80.          35.        ]]
-----===-----
[[-17.5   0. ]
 [ 80.   35. ]]


vertices:
[[  0.    0. ]
 [ 80.    0. ]
 [-17.5  17.5]
 [  0.   35. ]
 [ 80.   35. ]]
-----===-----
[[ -9.6649897   0.       ]
 [  0.          0.       ]
 [ 80.          0.       ]
 [-17.5         7.8350171]
 [-17.5        17.5      ]
 [-17.5        27.164983 ]
 [ -9.6649897  35.       ]
 [  0.         35.       ]
 [ 80.         35.       ]]


centroid:
[31.25000894 17.5       ]
-----===-----
[31.25 17.5 ]


length:
304.9557428756427
-----===-----
249.98557190148313


area:
3280.5362900551977
-----===-----
3281.159374448326


identifier:
[0.00000000e+00 3.28053629e+03 2.49963008e+02 3.28053629e+03
 2.49963008e+02 2.49963008e+02 2.42600946e+06 3.22584626e+05]
-----===-----
[0.00000000e+00 3.28115937e+03 2.49984680e+02 3.28115937e+03
 2.49984680e+02 2.49984680e+02 2.42724435e+06 3.22679987e+05]

[mikedh]

Hey, glad it's useful! Arcs should work fine assuming they're part of a closed contour. Does fill_gaps(distance=1.0) or some larger value work? Can you share the SVG that's failing?

[PetitPhoenix]

Hello,

fill_gaps(distance=1.0) doesn't work and fill_gaps(distance=10) neither.

the source is just above but if you need it, the code is:

<svg xmlns="http://www.w3.org/2000/svg" width="97.5mm" height="35mm" viewBox="-17.5 0 97.5 35">

<path d="M 0 0 h 80 v 35 h -80 a 17.5 17.5 0 0 1 0 -35 z" fill="none" stroke="black" stroke-width="0.1" />
</svg>

[mikedh]

It looks like it's the arc discretization not exactly matching the endpoints:

In [18]: p.discrete[0][[0,-1]]
Out[18]:
array([[ 0.00000000e+00,  0.00000000e+00],
       [-2.14313190e-15,  3.55271368e-15]])

1e-15 is below the trimesh threshold, but apparently above the earcut triangulation threshold. I added an endpoint snap to both bezier and 3-point arc discretization since both bezier curves and 3-point arcs start and end exactly on their control points and we don't have to approximate.