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fix find_noncollinear_points

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This commit is contained in:
Adrian Mariano 2020-07-28 17:54:45 -04:00
parent 65125ed57a
commit 3c9e304675
1 changed files with 27 additions and 8 deletions
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35
geometry.scad
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@ -1359,21 +1359,40 @@ function first_noncollinear(i1, i2, points) =
// find_noncollinear_points(points);
// Description:
// Finds the indices of three good non-collinear points from the points list `points`.
function find_noncollinear_points(points) =
function find_noncollinear_points(points,error=true,eps=EPSILON) =
let(
pa = points[0],
b = furthest_point(pa, points),
n = unit(points[b]-pa),
relpoints = [for(pt=points) pt-pa],
proj = relpoints * n,
distlist = [for(i=[0:len(points)-1]) norm(relpoints[i]-proj[i]*n)]
)
max(distlist)<eps
? assert(!error, "Cannot find three noncollinear points in pointlist.")
[]
: [0,b,max_index(distlist)];
function old_find_noncollinear_points(points,error=true) =
let(
a = 0,
b = furthest_point(points[a], points),
pa = points[a],
pb = points[b],
c = max_index([
for (p=points)
for (p=points)
(approx(p,pa) || approx(p,pb))? 0 :
sin(vector_angle(points[a]-p,points[b]-p)) *
norm(p-points[a]) * norm(p-points[b])
])
)
assert(c!=a && c!=b, "Cannot find three noncollinear points in pointlist.")
[a, b, c];
let(score =
sin(vector_angle(points[a]-p,points[b]-p)) *
norm(p-points[a]) * norm(p-points[b]),fff=echo(score=score))
approx(score,0,eps=1e-7) ? -1 : score])
,foo=echo(pval = a,b,c)
)
c ==a || c==b
? assert(!error, "Cannot find three noncollinear points in pointlist.")
[]
: [a, b, c];
// Function: pointlist_bounds()