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Improved centroid() to work with 3D planar polygons.

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This commit is contained in:
Revar Desmera 2019-12-05 14:01:40 -08:00
parent f0915b8e0b
commit 24de174d6f
2 changed files with 21 additions and 9 deletions
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28
geometry.scad
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@ -1090,16 +1090,28 @@ function find_noncollinear_points(points) =
// Function: centroid()
// Usage:
// centroid(vertices)
// cp = centroid(poly);
// Description:
// Given a simple 2D polygon, returns the coordinates of the polygon's centroid.
// Given a simple 2D polygon, returns the 2D coordinates of the polygon's centroid.
// Given a simple 3D planar polygon, returns the 3D coordinates of the polygon's centroid.
// If the polygon is self-intersecting, the results are undefined.
function centroid(vertices) =
sum([
for(i=[0:len(vertices)-1])
let(segment=select(vertices,i,i+1))
det2(segment)*sum(segment)
]) / 6 / polygon_area(vertices);
function centroid(poly) =
len(poly[0])==2? (
sum([
for(i=[0:len(poly)-1])
let(segment=select(poly,i,i+1))
det2(segment)*sum(segment)
]) / 6 / polygon_area(poly)
) : (
let(
n = plane_normal(plane_from_pointslist(poly)),
p1 = vector_angle(n,UP)>15? vector_axis(n,UP) : vector_axis(n,RIGHT),
p2 = vector_axis(n,p1),
cp = mean(poly),
proj = project_plane(poly,cp,cp+p1,cp+p2),
cxy = centroid(proj)
) lift_plane(cxy,cp,cp+p1,cp+p2)
);
// Function: simplify_path()

2
version.scad
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@ -8,7 +8,7 @@
//////////////////////////////////////////////////////////////////////
BOSL_VERSION = [2,0,53];
BOSL_VERSION = [2,0,54];
// Section: BOSL Library Version Functions