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https://github.com/revarbat/BOSL2.git
synced 2025-08-21 06:31:48 +02:00
Added regions and compound boolean 2d geometry.
This commit is contained in:
Revar Desmera
226
geometry.scad
226
geometry.scad
@@ -228,6 +228,7 @@ function triangle_area2d(a,b,c) =
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) / 2;
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// Section: Planes
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// Function: plane3pt()
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@@ -383,6 +384,23 @@ function point_in_polygon(point, path) =
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sum([for(i=[0:1:len(path)-1]) _point_above_below_segment(point, select(path, i, i+1))]) != 0 ? 1 : -1;
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// Function: point_in_region()
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// Usage:
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// point_in_region(point, region);
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// Description:
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// Tests if a point is inside, outside, or on the border of a region.
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// Returns -1 if the point is outside the region.
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// Returns 0 if the point is on the boundary.
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// Returns 1 if the point lies inside the region.
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// Arguments:
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// point = The point to test.
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// region = The region to test against. Given as a list of polygon paths.
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function point_in_region(point, region, _i=0, _cnt=0) =
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(_i >= len(region))? ((_cnt%2==1)? 1 : -1) : let(
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pip = point_in_polygon(point, region[_i])
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) pip==0? 0 : point_in_region(point, region, _i+1, _cnt + (pip>0? 1 : 0));
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// Function: pointlist_bounds()
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// Usage:
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// pointlist_bounds(pts);
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@@ -417,4 +435,212 @@ function polygon_clockwise(path) =
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det2( [select(path,extreme+1)-path[extreme], select(path, extreme-1)-path[extreme]])<0;
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// Section: Regions and Boolean 2D Geometry
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// Function: is_region()
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// Usage:
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// is_region(x);
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// Description:
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// Returns true if the given item looks like a region, which is a list of paths.
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function is_region(x) = is_list(x) && is_path(x.x);
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// Function: close_region(path)
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// Usage:
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// close_region(region);
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// Description:
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// Closes all paths within a given region.
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function close_region(region) = [for (path=region) close_path(path)];
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// Function: region_path_crossings()
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// Usage:
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// region_path_crossings(path, region);
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// Description:
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// Returns a sorted list of [SEGMENT, U] that describe where a given path is crossed by a second path.
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// Arguments:
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// path = The path to find crossings on.
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// region = Region to test for crossings of.
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function region_path_crossings(path, region) = sort([
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for (s1=enumerate(pair_wrap(path)), path=region, s2=pair_wrap(path)) let(
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isect = _general_line_intersection(s1.y,s2),
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eps = 1e-9
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) if (
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!is_undef(isect) &&
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isect[1] >= 0-eps && isect[1] < 1-eps &&
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isect[2] >= 0-eps && isect[2] < 1-eps
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) [s1.x, isect[1]]
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]);
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function _split_path_at_region_crossings(path, region, eps=1e-6) =
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let(
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path = deduplicate(path, eps=eps),
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region = [for (path=region) deduplicate(path, eps=eps)],
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crossings = deduplicate(concat(
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[[0,0]],
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region_path_crossings(path, region),
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[[len(path)-2,1]]
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))
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) [for (p = pair(crossings)) path_subselect(path, p[0][0], p[0][1], p[1][0], p[1][1])];
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function _tag_subpaths(path, region) =
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let(
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subpaths = _split_path_at_region_crossings(path, region),
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tagged = [
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for (subpath = subpaths) let(
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midpt = lerp(subpath[0], subpath[1], 0.5),
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rel = point_in_region(midpt,region)
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) rel<0? ["O", subpath] : rel>0? ["I", subpath] : let(
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sidept = midpt + rot(90, planar=true, p=normalize(subpath[0][1]-subpath[0][0])*0.01),
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rel2 = (point_in_region(sidept,region)>0) == (point_in_region(sidept,region)>0)
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) rel2? ["S", subpath] : ["U", subpath]
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]
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) tagged;
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function _tag_region_subpaths(region1, region2) =
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[for (path=region1) each _tag_subpaths(path, region2)];
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function _tagged_region(region1,region2,keep1,keep2) =
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let(
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region1 = close_region(region1),
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region2 = close_region(region2),
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tagged1 = _tag_region_subpaths(region1,region2),
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tagged2 = _tag_region_subpaths(region2,region1),
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tagged = concat(
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[for (tagpath = tagged1) if (in_list(tagpath[0], keep1)) tagpath[1]],
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[for (tagpath = tagged2) if (in_list(tagpath[0], keep2)) tagpath[1]]
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),
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outregion = assemble_path_fragments(tagged)
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) outregion;
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// Function: union()
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// Usage:
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// union(regions);
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// Description:
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// Given a list of regions, where each region is a list of closed 2D paths, returns the region boolean union of all given regions.
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// Arguments:
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// regions = List of regions to union. Each region is a list of closed paths.
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// Example(2D):
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// shape1 = move([-8,-8,0], p=circle(d=50));
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// shape2 = move([ 8, 8,0], p=circle(d=50));
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// for (shape = [shape1,shape2]) color("red") stroke(shape, width=0.5, close=true);
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// color("green") region(union(shape1,shape2));
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function union(regions=[],b=undef,c=undef) =
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b!=undef? union(concat([regions],[b],c==undef?[]:[c])) :
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len(regions)<=1? regions[0] :
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union(
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let(regions=[for (r=regions) is_path(r)? [r] : r])
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concat(
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[_tagged_region(regions[0],regions[1],["O","S"],["O"])],
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[for (i=[2:1:len(regions)-1]) regions[i]]
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)
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);
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// Function: difference()
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// Usage:
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// difference(regions);
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// Description:
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// Given a list of regions, where each region is a list of closed 2D paths, takes the first
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// region and differences away all other regions from it. The resulting region is returned.
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// Arguments:
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// regions = List of regions to difference. Each region is a list of closed paths.
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// Example(2D):
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// shape1 = move([-8,-8,0], p=circle(d=50));
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// shape2 = move([ 8, 8,0], p=circle(d=50));
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// for (shape = [shape1,shape2]) color("red") stroke(shape, width=0.5, close=true);
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// color("green") region(difference(shape1,shape2));
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function difference(regions=[],b=undef,c=undef) =
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b!=undef? difference(concat([regions],[b],c==undef?[]:[c])) :
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len(regions)<=1? regions[0] :
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difference(
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let(regions=[for (r=regions) is_path(r)? [r] : r])
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concat(
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[_tagged_region(regions[0],regions[1],["O","U"],["I"])],
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[for (i=[2:1:len(regions)-1]) regions[i]]
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)
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);
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// Function: intersection()
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// Usage:
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// intersection(regions);
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// Description:
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// Given a list of regions, where each region is a list of closed 2D paths, returns the region boolean intersection of all given regions.
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// Arguments:
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// regions = List of regions to intersection. Each region is a list of closed paths.
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// Example(2D):
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// shape1 = move([-8,-8,0], p=circle(d=50));
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// shape2 = move([ 8, 8,0], p=circle(d=50));
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// for (shape = [shape1,shape2]) color("red") stroke(shape, width=0.5, close=true);
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// color("green") region(intersection(shape1,shape2));
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function intersection(regions=[],b=undef,c=undef) =
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b!=undef? intersection(concat([regions],[b],c==undef?[]:[c])) :
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len(regions)<=1? regions[0] :
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intersection(
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let(regions=[for (r=regions) is_path(r)? [r] : r])
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concat(
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[_tagged_region(regions[0],regions[1],["I","S"],["I"])],
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[for (i=[2:1:len(regions)-1]) regions[i]]
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)
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);
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// Function: exclusive_or()
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// Usage:
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// exclusive_or(regions);
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// Description:
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// Given a list of regions, where each region is a list of closed 2D paths, returns the region boolean exclusive_or of all given regions.
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// Arguments:
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// regions = List of regions to exclusive_or. Each region is a list of closed paths.
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// Example(2D):
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// shape1 = move([-8,-8,0], p=circle(d=50));
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// shape2 = move([ 8, 8,0], p=circle(d=50));
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// for (shape = [shape1,shape2]) color("red") stroke(shape, width=0.5, close=true);
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// color("green") region(exclusive_or(shape1,shape2));
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function exclusive_or(regions=[],b=undef,c=undef) =
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b!=undef? exclusive_or(concat([regions],[b],c==undef?[]:[c])) :
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len(regions)<=1? regions[0] :
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exclusive_or(
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let(regions=[for (r=regions) is_path(r)? [r] : r])
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concat(
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[union([
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difference([regions[0],regions[1]]),
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difference([regions[1],regions[0]])
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])],
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[for (i=[2:1:len(regions)-1]) regions[i]]
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)
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);
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// Module: region()
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// Usage:
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// region(r);
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// Description:
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// Creates 2D polygons for the given region.
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// Example(2D):
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// shape1 = circle(d=50);
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// shape2 = circle(d=30);
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// region([shape1,shape2]);
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module region(r)
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{
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points = flatten(r);
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paths = [
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for (i=[0:1:len(r)-1]) let(
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start = default(sum([for (j=[0:1:i-1]) len(r[j])]),0)
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) [for (k=[0:1:len(r[i])-1]) start+k]
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];
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polygon(points=points, paths=paths);
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}
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// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap
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