76 lines
2.4 KiB
OpenSCAD
76 lines
2.4 KiB
OpenSCAD
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use <scad-utils/transformations.scad>
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use <scad-utils/lists.scad>
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// Skin a set of profiles with a polyhedral mesh
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module skin(profiles, loop=false /* unimplemented */) {
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P = max_len(profiles);
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N = len(profiles);
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profiles = [
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for (p = profiles)
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for (pp = augment_profile(to_3d(p),P))
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pp
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];
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function quad(i,P,o) = [[o+i, o+i+P, o+i%P+P+1], [o+i, o+i%P+P+1, o+i%P+1]];
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function profile_triangles(tindex) = [
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for (index = [0:P-1])
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let (qs = quad(index+1, P, P*(tindex-1)-1))
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for (q = qs) q
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];
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triangles = [
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for(index = [1:N-1])
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for(t = profile_triangles(index))
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t
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];
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start_cap = [range([0:P-1])];
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end_cap = [range([P*N-1 : -1 : P*(N-1)])];
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polyhedron(convexity=2, points=profiles, faces=concat(start_cap, triangles, end_cap));
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}
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// Augments the profile with steiner points making the total number of vertices n
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function augment_profile(profile, n) =
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subdivide(profile,insert_extra_vertices_0([profile_lengths(profile),dup(0,len(profile))],n-len(profile))[1]);
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function subdivide(profile,subdivisions) = let (N=len(profile)) [
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for (i = [0:N-1])
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let(n = len(subdivisions)>0 ? subdivisions[i] : subdivisions)
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for (p = interpolate(profile[i],profile[(i+1)%N],n+1))
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p
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];
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function interpolate(a,b,subdivisions) = [
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for (index = [0:subdivisions-1])
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let(t = index/subdivisions)
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a*(1-t)+b*t
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];
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function distribute_extra_vertex(lengths_count,ma_=-1) = ma_<0 ? distribute_extra_vertex(lengths_count, max_element(lengths_count[0])) :
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concat([set(lengths_count[0],ma_,lengths_count[0][ma_] * (lengths_count[1][ma_]+1) / (lengths_count[1][ma_]+2))], [increment(lengths_count[1],max_element(lengths_count[0]),1)]);
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function insert_extra_vertices_0(lengths_count,n_extra) = n_extra <= 0 ? lengths_count :
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insert_extra_vertices_0(distribute_extra_vertex(lengths_count),n_extra-1);
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// Find the index of the maximum element of arr
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function max_element(arr,ma_,ma_i_=-1,i_=0) = i_ >= len(arr) ? ma_i_ :
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i_ == 0 || arr[i_] > ma_ ? max_element(arr,arr[i_],i_,i_+1) : max_element(arr,ma_,ma_i_,i_+1);
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function max_len(arr) = max([for (i=arr) len(i)]);
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function increment(arr,i,x=1) = set(arr,i,arr[i]+x);
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function profile_lengths(profile) = [
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for (i = [0:len(profile)-1])
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profile_segment_length(profile,i)
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];
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function profile_segment_length(profile,i) = norm(profile[(i+1)%len(profile)] - profile[i]);
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// Generates an array with n copies of value (default 0)
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function dup(value=0,n) = [for (i = [1:n]) value];
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