Polygon simplification option upon 2D file import

[pruj-speed]

Hi folks,

I have been using cadquery to convert 2d polygons into 3D. It has been working great so far. I notice that the gds and dxf representation of curved geometries is a bunch of line segments. When I extrude them to 3D I end up with a bunch of surfaces that take up a lot of memory. On my most recent 2d to 3D conversion I ended up with a step file of ~ 1GB. I manually recreated a similar geometry where I defined the curved surfaces as a 3D primitive and see a 10X drop in file size. This is due to far fewer surfaces.

I did a google search and looks like this is an option in several commerical packages

1. https://space.mit.edu/RADIO/CST_online/mergedProjects/3D/common_tools/common_tools_polygonsimplification.htm
2. https://pro.arcgis.com/en/pro-app/latest/tool-reference/editing/simplifybystraightlinesandcirculararcs.htm

I think this will be a great feature for folks who work with 2D layouts and convert it to 3D. Of course not sure how challenging it would be to implement this pipeline.

Sharing an example polygon that I was extruding for illustration

import cadquery as cq
from cadquery.vis import show

# pts is a list of (x,y) tuples from GDS polygon
pts =[
    (-15.00000, -20.00000),
    (-16.96050, -19.90350),
    (-18.90200, -19.61550),
    (-20.80550, -19.13900),
    (-22.65350, -18.47750),
    (-24.42800, -17.63850),
    (-26.11150, -16.62950),
    (-27.68800, -15.46000),
    (-29.14200, -14.14200),
    (-30.46000, -12.68800),
    (-31.62950, -11.11150),
    (-32.63850, -9.42800),
    (-33.47750, -7.65350),
    (-34.13900, -5.80550),
    (-34.61550, -3.90200),
    (-34.90350, -1.96050),
    (-35.00000, 0.00000),
    (-34.90350, 1.96050),
    (-34.61550, 3.90200),
    (-34.13900, 5.80550),
    (-33.47750, 7.65350),
    (-32.63850, 9.42800),
    (-31.62950, 11.11150),
    (-30.46000, 12.68800),
    (-29.14200, 14.14200),
    (-27.68800, 15.46000),
    (-26.11150, 16.62950),
    (-24.42800, 17.63850),
    (-22.65350, 18.47750),
    (-20.80550, 19.13900),
    (-18.90200, 19.61550),
    (-16.96050, 19.90350),
    (-15.00000, 20.00000),
    (15.00000, 20.00000),
    (16.96050, 19.90350),
    (18.90200, 19.61550),
    (20.80550, 19.13900),
    (22.65350, 18.47750),
    (24.42800, 17.63850),
    (26.11150, 16.62950),
    (27.68800, 15.46000),
    (29.14200, 14.14200),
    (30.46000, 12.68800),
    (31.62950, 11.11150),
    (32.63850, 9.42800),
    (33.47750, 7.65350),
    (34.13900, 5.80550),
    (34.61550, 3.90200),
    (34.90350, 1.96050),
    (35.00000, 0.00000),
    (34.90350, -1.96050),
    (34.61550, -3.90200),
    (34.13900, -5.80550),
    (33.47750, -7.65350),
    (32.63850, -9.42800),
    (31.62950, -11.11150),
    (30.46000, -12.68800),
    (29.14200, -14.14200),
    (27.68800, -15.46000),
    (26.11150, -16.62950),
    (24.42800, -17.63850),
    (22.65350, -18.47750),
    (20.80550, -19.13900),
    (18.90200, -19.61550),
    (16.96050, -19.90350),
    (15.00000, -20.00000),
]


wire = (
    cq.Workplane("XY")
    .polyline(pts)
    .close()  
)

#wire = (
#    cq.Workplane("XY")
#    .spline(pts).close() 
#)

solid = wire.extrude(5.0)

show(solid)

When I export to STEP the raw polyline based solid is ~240KB, the one with the spline results in ~38KB.