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Correction in is_convex_polygon

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This commit is contained in:
RonaldoCMP 2021-04-11 23:45:21 +01:00
parent dab6407b0f
commit 41616872fe
2 changed files with 7 additions and 5 deletions
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11
geometry.scad
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@ -1304,7 +1304,7 @@ function _pointlist_greatest_distance(points,plane) =
normal = point3d(plane), normal = point3d(plane),
pt_nrm = points*normal pt_nrm = points*normal
) )
abs(max( max(pt_nrm) - plane[3], -min(pt_nrm)+plane[3])) / norm(normal); abs(max( max(pt_nrm) - plane[3], -min(pt_nrm) + plane[3])) / norm(normal);
// Function: points_on_plane() // Function: points_on_plane()
@ -1786,7 +1786,7 @@ function polygon_area(poly, signed=false) =
: let( plane = plane_from_polygon(poly) ) : let( plane = plane_from_polygon(poly) )
plane==[]? [] : plane==[]? [] :
let( let(
n = plane_normal(plane), n = plane_normal(plane),
total = sum([ total = sum([
for(i=[1:1:len(poly)-2]) for(i=[1:1:len(poly)-2])
let( let(
@ -1808,25 +1808,26 @@ function polygon_area(poly, signed=false) =
// If the points are collinear an error is generated. // If the points are collinear an error is generated.
// Arguments: // Arguments:
// poly = Polygon to check. // poly = Polygon to check.
// eps = Tolerance for the collinearity test. Default: EPSILON.
// Example: // Example:
// is_convex_polygon(circle(d=50)); // Returns: true // is_convex_polygon(circle(d=50)); // Returns: true
// is_convex_polygon(rot([50,120,30], p=path3d(circle(1,$fn=50)))); // Returns: true // is_convex_polygon(rot([50,120,30], p=path3d(circle(1,$fn=50)))); // Returns: true
// Example: // Example:
// spiral = [for (i=[0:36]) let(a=-i*10) (10+i)*[cos(a),sin(a)]]; // spiral = [for (i=[0:36]) let(a=-i*10) (10+i)*[cos(a),sin(a)]];
// is_convex_polygon(spiral); // Returns: false // is_convex_polygon(spiral); // Returns: false
function is_convex_polygon(poly) = function is_convex_polygon(poly,eps=EPSILON) =
assert(is_path(poly), "The input should be a 2D or 3D polygon." ) assert(is_path(poly), "The input should be a 2D or 3D polygon." )
let( lp = len(poly), let( lp = len(poly),
p0 = poly[0] ) p0 = poly[0] )
assert( lp>=3 , "A polygon must have at least 3 points" ) assert( lp>=3 , "A polygon must have at least 3 points" )
let( crosses = [for(i=[0:1:lp-1]) cross(poly[(i+1)%lp]-poly[i], poly[(i+2)%lp]-poly[(i+1)%lp]) ] ) let( crosses = [for(i=[0:1:lp-1]) cross(poly[(i+1)%lp]-poly[i], poly[(i+2)%lp]-poly[(i+1)%lp]) ] )
len(p0)==2 len(p0)==2
? assert( !approx(max(crosses)) && !approx(min(crosses)), "The points are collinear" ) ? assert( !approx(sqrt(max(max(crosses),-min(crosses))),eps), "The points are collinear" )
min(crosses) >=0 || max(crosses)<=0 min(crosses) >=0 || max(crosses)<=0
: let( prod = crosses*sum(crosses), : let( prod = crosses*sum(crosses),
minc = min(prod), minc = min(prod),
maxc = max(prod) ) maxc = max(prod) )
assert( !approx(maxc-minc), "The points are collinear" ) assert( !approx(sqrt(max(maxc,-minc)),eps), "The points are collinear" )
minc>=0 || maxc<=0; minc>=0 || maxc<=0;

1
tests/test_geometry.scad
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@ -847,6 +847,7 @@ module test_is_convex_polygon() {
assert(is_convex_polygon(circle(r=50,$fn=1000))); assert(is_convex_polygon(circle(r=50,$fn=1000)));
assert(is_convex_polygon(rot([50,120,30], p=path3d(circle(1,$fn=50))))); assert(is_convex_polygon(rot([50,120,30], p=path3d(circle(1,$fn=50)))));
assert(!is_convex_polygon([[1,1],[0,0],[-1,1],[-1,-1],[1,-1]])); assert(!is_convex_polygon([[1,1],[0,0],[-1,1],[-1,-1],[1,-1]]));
assert(!is_convex_polygon([for (i=[0:36]) let(a=-i*10) (10+i)*[cos(a),sin(a)]])); // spiral
} }
*test_is_convex_polygon(); *test_is_convex_polygon();