BOSL2/vnf.scad
2020-03-30 19:17:27 -04:00

672 lines
21 KiB
OpenSCAD

//////////////////////////////////////////////////////////////////////
// LibFile: vnf.scad
// VNF structures, holding Vertices 'N' Faces for use with `polyhedron().`
// To use, add the following lines to the beginning of your file:
// ```
// use <BOSL2/std.scad>
// use <BOSL2/vnf.scad>
// ```
//////////////////////////////////////////////////////////////////////
include <triangulation.scad>
// Section: Creating Polyhedrons with VNF Structures
// VNF stands for "Vertices'N'Faces". VNF structures are 2-item lists, `[VERTICES,FACES]` where the
// first item is a list of vertex points, and the second is a list of face indices into the vertex
// list. Each VNF is self contained, with face indices referring only to its own vertex list.
// You can construct a `polyhedron()` in parts by describing each part in a self-contained VNF, then
// merge the various VNFs to get the completed polyhedron vertex list and faces.
EMPTY_VNF = [[],[]]; // The standard empty VNF with no vertices or faces.
// Function: is_vnf()
// Usage:
// bool = is_vnf(x);
// Description:
// Returns true if the given value looks like a VNF structure.
function is_vnf(x) =
is_list(x) &&
len(x)==2 &&
is_list(x[0]) &&
is_list(x[1]) &&
(x[0]==[] || (len(x[0])>=3 && is_vector(x[0][0]))) &&
(x[1]==[] || is_vector(x[1][0]));
// Function: is_vnf_list()
// Description: Returns true if the given value looks passingly like a list of VNF structures.
function is_vnf_list(x) = is_list(x) && all([for (v=x) is_vnf(v)]);
// Function: vnf_vertices()
// Description: Given a VNF structure, returns the list of vertex points.
function vnf_vertices(vnf) = vnf[0];
// Function: vnf_faces()
// Description: Given a VNF structure, returns the list of faces, where each face is a list of indices into the VNF vertex list.
function vnf_faces(vnf) = vnf[1];
// Function: vnf_quantize()
// Usage:
// vnf2 = vnf_quantize(vnf,[q]);
// Description:
// Quantizes the vertex coordinates of the VNF to the given quanta `q`.
// Arguments:
// vnf = The VNF to quantize.
// q = The quanta to quantize the VNF coordinates to.
function vnf_quantize(vnf,q=pow(2,-12)) =
[[for (pt = vnf[0]) quant(pt,q)], vnf[1]];
// Function: vnf_get_vertex()
// Usage:
// vvnf = vnf_get_vertex(vnf, p);
// Description:
// Finds the index number of the given vertex point `p` in the given VNF structure `vnf`. If said
// point does not already exist in the VNF vertex list, it is added. Returns: `[INDEX, VNF]` where
// INDEX if the index of the point, and VNF is the possibly modified new VNF structure.
// If `p` is given as a list of points, then INDEX will be a list of indices.
// Arguments:
// vnf = The VNF structue to get the point index from.
// p = The point, or list of points to get the index of.
// Example:
// vnf1 = vnf_get_vertex(p=[3,5,8]); // Returns: [0, [[[3,5,8]],[]]]
// vnf2 = vnf_get_vertex(vnf1, p=[3,2,1]); // Returns: [1, [[[3,5,8],[3,2,1]],[]]]
// vnf3 = vnf_get_vertex(vnf2, p=[3,5,8]); // Returns: [0, [[[3,5,8],[3,2,1]],[]]]
// vnf4 = vnf_get_vertex(vnf3, p=[[1,3,2],[3,2,1]]); // Returns: [[1,2], [[[3,5,8],[3,2,1],[1,3,2]],[]]]
function vnf_get_vertex(vnf=EMPTY_VNF, p) =
is_path(p)? _vnf_get_vertices(vnf, p) :
assert(is_list(vnf) && len(vnf)==2 && is_list(vnf[0]) && is_list(vnf[1]), "Argument vnf should contain a VNF structure.")
assert(is_vector(p))
let(
v = search([p], vnf[0])[0]
) [
v != []? v : len(vnf[0]),
[
concat(vnf[0], v != []? [] : [p]),
vnf[1]
]
];
// Internal use only
function _vnf_get_vertices(vnf=EMPTY_VNF, pts, _i=0, _idxs=[]) =
_i>=len(pts)? [_idxs, vnf] :
let(
vvnf = vnf_get_vertex(vnf, pts[_i])
) _vnf_get_vertices(vvnf[1], pts, _i=_i+1, _idxs=concat(_idxs,[vvnf[0]]));
// Function: vnf_add_face()
// Usage:
// vnf_add_face(vnf, pts);
// Description:
// Given a VNF structure and a list of face vertex points, adds the face to the VNF structure.
// Returns the modified VNF structure `[VERTICES, FACES]`. It is up to the caller to make
// sure that the points are in the correct order to make the face normal point outwards.
// Arguments:
// vnf = The VNF structure to add a face to.
// pts = The vertex points for the face.
function vnf_add_face(vnf=EMPTY_VNF, pts) =
assert(is_vnf(vnf))
assert(is_path(pts))
let(
vvnf = vnf_get_vertex(vnf, pts),
face = deduplicate(vvnf[0], closed=true),
vnf2 = vvnf[1]
) [
vnf_vertices(vnf2),
concat(vnf_faces(vnf2), len(face)>2? [face] : [])
];
// Function: vnf_add_faces()
// Usage:
// vnf_add_faces(vnf, faces);
// Description:
// Given a VNF structure and a list of faces, where each face is given as a list of vertex points,
// adds the faces to the VNF structure. Returns the modified VNF structure `[VERTICES, FACES]`.
// It is up to the caller to make sure that the points are in the correct order to make the face
// normals point outwards.
// Arguments:
// vnf = The VNF structure to add a face to.
// faces = The list of faces, where each face is given as a list of vertex points.
function vnf_add_faces(vnf=EMPTY_VNF, faces, _i=0) =
(assert(is_vnf(vnf)) assert(is_list(faces)) _i>=len(faces))? vnf :
vnf_add_faces(vnf_add_face(vnf, faces[_i]), faces, _i=_i+1);
// Function: vnf_merge()
// Usage:
// vnf = vnf_merge([VNF, VNF, VNF, ...]);
// Description:
// Given a list of VNF structures, merges them all into a single VNF structure.
function vnf_merge(vnfs=[],_i=0,_acc=EMPTY_VNF) =
(assert(is_vnf_list(vnfs)) _i>=len(vnfs))? _acc :
vnf_merge(
vnfs, _i=_i+1,
_acc = let(base=len(_acc[0])) [
concat(_acc[0], vnfs[_i][0]),
concat(_acc[1], [for (f=vnfs[_i][1]) [for (i=f) i+base]]),
]
);
// Function: vnf_compact()
// Usage:
// cvnf = vnf_compact(vnf);
// Description:
// Takes a VNF and consolidates all duplicate vertices, and drops unreferenced vertices.
function vnf_compact(vnf) =
let(
verts = vnf[0],
faces = [
for (face=vnf[1]) [
for (i=face) verts[i]
]
]
) vnf_add_faces(faces=faces);
// Function: vnf_triangulate()
// Usage:
// vnf2 = vnf_triangulate(vnf);
// Description:
// Forces triangulation of faces in the VNF that have more than 3 vertices.
function vnf_triangulate(vnf) =
let(
vnf = is_vnf_list(vnf)? vnf_merge(vnf) : vnf
) [vnf[0], triangulate_faces(vnf[0], vnf[1])];
// Function: vnf_vertex_array()
// Usage:
// vnf = vnf_vertex_array(points, [caps], [cap1], [cap2], [reverse], [col_wrap], [row_wrap], [vnf]);
// Description:
// Creates a VNF structure from a vertex list, by dividing the vertices into columns and rows,
// adding faces to tile the surface. You can optionally have faces added to wrap the last column
// back to the first column, or wrap the last row to the first. Endcaps can be added to either
// the first and/or last rows.
// Arguments:
// points = A list of vertices to divide into columns and rows.
// caps = If true, add endcap faces to the first AND last rows.
// cap1 = If true, add an endcap face to the first row.
// cap2 = If true, add an endcap face to the last row.
// col_wrap = If true, add faces to connect the last column to the first.
// row_wrap = If true, add faces to connect the last row to the first.
// reverse = If true, reverse all face normals.
// style = The style of subdividing the quads into faces. Valid options are "default", "alt", and "quincunx".
// vnf = If given, add all the vertices and faces to this existing VNF structure.
// Example(3D):
// vnf = vnf_vertex_array(
// points=[
// for (h = [0:5:180-EPSILON]) [
// for (t = [0:5:360-EPSILON])
// cylindrical_to_xyz(100 + 12 * cos((h/2 + t)*6), t, h)
// ]
// ],
// col_wrap=true, caps=true, reverse=true, style="alt"
// );
// vnf_polyhedron(vnf);
// Example(3D): Both `col_wrap` and `row_wrap` are true to make a torus.
// vnf = vnf_vertex_array(
// points=[
// for (a=[0:5:360-EPSILON])
// apply(
// zrot(a) * right(30) * xrot(90),
// path3d(circle(d=20))
// )
// ],
// col_wrap=true, row_wrap=true, reverse=true
// );
// vnf_polyhedron(vnf);
// Example(3D): Möbius Strip. Note that `row_wrap` is not used, and the first and last profile copies are the same.
// vnf = vnf_vertex_array(
// points=[
// for (a=[0:5:360]) apply(
// zrot(a) * right(30) * xrot(90) * zrot(a/2+60),
// path3d(square([1,10], center=true))
// )
// ],
// col_wrap=true, reverse=true
// );
// vnf_polyhedron(vnf);
// Example(3D): Assembling a Polyhedron from Multiple Parts
// wall_points = [
// for (a = [-90:2:90]) apply(
// up(a) * scale([1-0.1*cos(a*6),1-0.1*cos((a+90)*6),1]),
// path3d(circle(d=100))
// )
// ];
// cap = [
// for (a = [0:0.01:1+EPSILON]) apply(
// up(90-5*sin(a*360*2)) * scale([a,a,1]),
// wall_points[0]
// )
// ];
// cap1 = [for (p=cap) down(90, p=zscale(-1, p=p))];
// cap2 = [for (p=cap) up(90, p=p)];
// vnf1 = vnf_vertex_array(points=wall_points, col_wrap=true);
// vnf2 = vnf_vertex_array(points=cap1, col_wrap=true);
// vnf3 = vnf_vertex_array(points=cap2, col_wrap=true, reverse=true);
// vnf_polyhedron([vnf1, vnf2, vnf3]);
function vnf_vertex_array(
points,
caps, cap1, cap2,
col_wrap=false,
row_wrap=false,
reverse=false,
style="default",
vnf=EMPTY_VNF
) =
assert((!caps)||(caps&&col_wrap))
assert(in_list(style,["default","alt","quincunx"]))
let(
pts = flatten(points),
pcnt = len(pts),
rows = len(points),
cols = len(points[0]),
errchk = [for (row=points) assert(len(row)==cols, "All rows much have the same number of columns.") 0],
cap1 = first_defined([cap1,caps,false]),
cap2 = first_defined([cap2,caps,false]),
colcnt = cols - (col_wrap?0:1),
rowcnt = rows - (row_wrap?0:1)
)
vnf_merge([
vnf, [
concat(
pts,
style!="quincunx"? [] : [
for (r = [0:1:rowcnt-1]) (
for (c = [0:1:colcnt-1]) (
let(
i1 = ((r+0)%rows)*cols + ((c+0)%cols),
i2 = ((r+1)%rows)*cols + ((c+0)%cols),
i3 = ((r+1)%rows)*cols + ((c+1)%cols),
i4 = ((r+0)%rows)*cols + ((c+1)%cols)
) mean([pts[i1], pts[i2], pts[i3], pts[i4]])
)
)
]
),
concat(
[
for (r = [0:1:rowcnt-1]) (
for (c = [0:1:colcnt-1]) each (
let(
i1 = ((r+0)%rows)*cols + ((c+0)%cols),
i2 = ((r+1)%rows)*cols + ((c+0)%cols),
i3 = ((r+1)%rows)*cols + ((c+1)%cols),
i4 = ((r+0)%rows)*cols + ((c+1)%cols)
)
style=="quincunx"? (
let(i5 = pcnt + r*colcnt + c)
reverse? [[i1,i2,i5],[i2,i3,i5],[i3,i4,i5],[i4,i1,i5]] : [[i1,i5,i2],[i2,i5,i3],[i3,i5,i4],[i4,i5,i1]]
) : style=="alt"? (
reverse? [[i1,i2,i4],[i2,i3,i4]] : [[i1,i4,i2],[i2,i4,i3]]
) : (
reverse? [[i1,i2,i3],[i1,i3,i4]] : [[i1,i3,i2],[i1,i4,i3]]
)
)
)
],
!cap1? [] : [
reverse?
[for (c = [0:1:cols-1]) c] :
[for (c = [cols-1:-1:0]) c]
],
!cap2? [] : [
reverse?
[for (c = [cols-1:-1:0]) (rows-1)*cols + c] :
[for (c = [0:1:cols-1]) (rows-1)*cols + c]
]
)
]
]);
// Module: vnf_polyhedron()
// Usage:
// vnf_polyhedron(vnf);
// vnf_polyhedron([VNF, VNF, VNF, ...]);
// Description:
// Given a VNF structure, or a list of VNF structures, creates a polyhedron from them.
// Arguments:
// vnf = A VNF structure, or list of VNF structures.
// convexity = Max number of times a line could intersect a wall of the shape.
module vnf_polyhedron(vnf, convexity=2) {
vnf = is_vnf_list(vnf)? vnf_merge(vnf) : vnf;
polyhedron(vnf[0], vnf[1], convexity=convexity);
}
// Function: vnf_volume()
// Usage:
// vol = vnf_volume(vnf);
// Description:
// Returns the volume enclosed by the given manifold VNF. The VNF must describe a valid polyhedron with consistent face direction and
// no holes; otherwise the results are undefined. Returns a positive volume if face direction is clockwise and a negative volume
// if face direction is counter-clockwise.
function vnf_volume(vnf) =
let(vnf = vnf_triangulate(vnf),
vert=vnf[0])
sum([
for(face_index=vnf[1]) let(
face = select(vert, face_index),
n = cross(face[2]-face[0],face[1]-face[0])
) face[0] * n
])/6;
// Function: vnf_centroid()
// Usage:
// vol = vnf_centroid(vnf);
// Description:
// Returns the centroid of the given manifold VNF. The VNF must describe a valid polyhedron with consistent face direction and
// no holes; otherwise the results are undefined.
// Algorithm from: https://wwwf.imperial.ac.uk/~rn/centroid.pdf
function vnf_centroid(vnf) =
let(
vnf = vnf_triangulate(vnf),
vert = vnf[0],
val=sum([
for(face_index=vnf[1])
let(
face = select(vert, face_index),
n = cross(face[2]-face[0],face[1]-face[0])
) [
face[0] * n,
vmul(n,
sqr(face[0] + face[1]) +
sqr(face[0] + face[2]) +
sqr(face[1] + face[2])
)
]
])
) val[1]/val[0]/8;
// Function&Module: vnf_validate()
// Usage: As Function
// fails = vnf_validate(vnf);
// Usage: As Module
// vnf_validate(vnf);
// Description:
// When called as a function, returns a list of non-manifold errors with the given VNF.
// Each error has the format `[ERR_OR_WARN,CODE,MESG,POINTS,COLOR]`.
// When called as a module, echoes the non-manifold errors to the console, and color hilites the
// bad edges and vertices, overlaid on a transparent gray polyhedron of the VNF.
//
// Currently checks for these problems:
// Type | Color | Code | Message
// ------- | -------- | ------------ | ---------------------------------
// WARNING | Yellow | BIG_FACE | Face has more than 3 vertices, and may confuse CGAL
// WARNING | Brown | NULL_FACE | Face has zero area
// ERROR | Cyan | NONPLANAR | Face vertices are not coplanar
// ERROR | Orange | OVRPOP_EDGE | Too many faces attached at edge
// ERROR | Violet | REVERSAL | Faces reverse across edge
// ERROR | Red | T_JUNCTION | Vertex is mid-edge on another Face
// ERROR | Blue | FACE_ISECT | Faces intersect
// ERROR | Magenta | HOLE_EDGE | Edge bounds Hole
//
// Still to implement:
// - Overlapping coplanar faces.
// Arguments:
// vnf = The VNF to validate.
// size = The width of the lines and diameter of points used to highlight edges and vertices. Module only. Default: 1
// check_isects = If true, performs slow checks for intersecting faces. Default: false
// Example: BIG_FACE Warnings; Faces with More Than 3 Vertices. CGAL often will fail to accept that a face is planar after a rotation, if it has more than 3 vertices.
// vnf = skin([
// path3d(regular_ngon(n=3, d=100),0),
// path3d(regular_ngon(n=5, d=100),100)
// ], slices=0, caps=true, method="tangent");
// vnf_validate(vnf);
// Example: NONPLANAR Errors; Face Vertices are Not Coplanar
// a = [ 0, 0,-50];
// b = [-50,-50, 50];
// c = [-50, 50, 50];
// d = [ 50, 50, 60];
// e = [ 50,-50, 50];
// vnf = vnf_add_faces(faces=[
// [a, b, e], [a, c, b], [a, d, c], [a, e, d], [b, c, d, e]
// ]);
// vnf_validate(vnf);
// Example: OVRPOP_EDGE Errors; More Than Two Faces Attached to the Same Edge. This confuses CGAL, and can lead to failed renders.
// vnf = vnf_triangulate(linear_sweep(union(square(50), square(50,anchor=BACK+RIGHT)), height=50));
// vnf_validate(vnf);
// Example: REVERSAL Errors; Faces Reversed Across Edge
// vnf1 = skin([
// path3d(square(100,center=true),0),
// path3d(square(100,center=true),100),
// ], slices=0, caps=false);
// vnf = vnf_add_faces(vnf=vnf1, faces=[
// [[-50,-50, 0], [ 50, 50, 0], [-50, 50, 0]],
// [[-50,-50, 0], [ 50,-50, 0], [ 50, 50, 0]],
// [[-50,-50,100], [-50, 50,100], [ 50, 50,100]],
// [[-50,-50,100], [ 50,-50,100], [ 50, 50,100]],
// ]);
// vnf_validate(vnf);
// Example: T_JUNCTION Errors; Vertex is Mid-Edge on Another Face.
// vnf1 = skin([
// path3d(square(100,center=true),0),
// path3d(square(100,center=true),100),
// ], slices=0, caps=false);
// vnf = vnf_add_faces(vnf=vnf1, faces=[
// [[-50,-50,0], [50,50,0], [-50,50,0]],
// [[-50,-50,0], [50,-50,0], [50,50,0]],
// [[-50,-50,100], [-50,50,100], [0,50,100]],
// [[-50,-50,100], [0,50,100], [0,-50,100]],
// [[0,-50,100], [0,50,100], [50,50,100]],
// [[0,-50,100], [50,50,100], [50,-50,100]],
// ]);
// vnf_validate(vnf);
// Example: FACE_ISECT Errors; Faces Intersect
// vnf = vnf_merge([
// vnf_triangulate(linear_sweep(square(100,center=true), height=100)),
// move([75,35,30],p=vnf_triangulate(linear_sweep(square(100,center=true), height=100)))
// ]);
// vnf_validate(vnf,size=2,check_isects=true);
// Example: HOLE_EDGE Errors; Edges Adjacent to Holes.
// vnf = skin([
// path3d(regular_ngon(n=4, d=100),0),
// path3d(regular_ngon(n=5, d=100),100)
// ], slices=0, caps=false);
// vnf_validate(vnf,size=2);
function vnf_validate(vnf, show_warns=true, check_isects=false) =
let(
vnf = vnf_compact(vnf),
edges = sort([
for (face=vnf[1], edge=pair_wrap(face))
edge[0]<edge[1]? edge : [edge[1],edge[0]]
]),
edgecnts = unique_count(edges),
uniq_edges = edgecnts[0],
big_faces = !show_warns? [] : [
for (face = vnf[1])
if (len(face) > 3) [
"WARNING",
"BIG_FACE",
"Face has more than 3 vertices, and may confuse CGAL",
[for (i=face) vnf[0][i]],
"yellow"
]
],
null_faces = !show_warns? [] : [
for (face = vnf[1]) let(
verts = [for (k=face) vnf[0][k]],
area = abs(polygon_area(verts))
) if (area < EPSILON) [
"WARNING",
"NULL_FACE",
str("Face has zero area: ",fmt_float(area,15)),
verts,
"brown"
]
],
nonplanars = unique([
for (face = vnf[1]) let(
verts = [for (k=face) vnf[0][k]]
) if (!points_are_coplanar(verts)) [
"ERROR",
"NONPLANAR",
"Face vertices are not coplanar",
verts,
"cyan"
]
]),
overpop_edges = unique([
for (i=idx(uniq_edges))
if (edgecnts[1][i]>2) [
"ERROR",
"OVRPOP_EDGE",
"Too many faces attached at Edge",
[for (i=uniq_edges[i]) vnf[0][i]],
"#f70"
]
]),
reversals = unique([
for(i = idx(vnf[1]), j = idx(vnf[1])) if(i != j)
for(edge1 = pair_wrap(vnf[1][i]))
for(edge2 = pair_wrap(vnf[1][j]))
if(edge1 == edge2) // Valid adjacent faces will never have the same vertex ordering.
if(_edge_not_reported(edge1, vnf, overpop_edges))
[
"ERROR",
"REVERSAL",
"Faces Reverse Across Edge",
[for (i=edge1) vnf[0][i]],
"violet"
]
]),
t_juncts = unique([
for (v=idx(vnf[0]), edge=uniq_edges)
if (v!=edge[0] && v!=edge[1]) let(
a = vnf[0][edge[0]],
b = vnf[0][v],
c = vnf[0][edge[1]],
pt = segment_closest_point([a,c],b)
) if (pt == b) [
"ERROR",
"T_JUNCTION",
"Vertex is mid-edge on another Face",
[b],
"red"
]
]),
isect_faces = !check_isects? [] : unique([
for (i = [0:1:len(vnf[1])-2])
for (j = [i+1:1:len(vnf[1])-1]) let(
f1 = vnf[1][i],
f2 = vnf[1][j],
shared_edges = [
for (edge1 = pair_wrap(f1), edge2 = pair_wrap(f2)) let(
e1 = edge1[0]<edge1[1]? edge1 : [edge1[1],edge1[0]],
e2 = edge2[0]<edge2[1]? edge2 : [edge2[1],edge2[0]]
) if (e1==e2) 1
]
)
if (!shared_edges) let(
plane1 = plane3pt_indexed(vnf[0], f1[0], f1[1], f1[2]),
plane2 = plane3pt_indexed(vnf[0], f2[0], f2[1], f2[2]),
line = plane_intersection(plane1, plane2)
)
if (!is_undef(line)) let(
poly1 = select(vnf[0],f1),
isects = polygon_line_intersection(poly1,line)
)
if (!is_undef(isects))
for (isect=isects)
if (len(isect)>1) let(
poly2 = select(vnf[0],f2),
isects2 = polygon_line_intersection(poly2,isect,bounded=true)
)
if (!is_undef(isects2))
for (seg=isects2)
if (seg[0] != seg[1]) [
"ERROR",
"FACE_ISECT",
"Faces intersect",
seg,
"blue"
]
]),
hole_edges = unique([
for (i=idx(uniq_edges))
if (edgecnts[1][i]<2)
if (_pts_not_reported(uniq_edges[i], vnf, t_juncts))
if (_pts_not_reported(uniq_edges[i], vnf, isect_faces))
[
"ERROR",
"HOLE_EDGE",
"Edge bounds Hole",
[for (i=uniq_edges[i]) vnf[0][i]],
"magenta"
]
])
) concat(
big_faces,
null_faces,
nonplanars,
overpop_edges,
reversals,
t_juncts,
isect_faces,
hole_edges
);
function _pts_not_reported(pts, vnf, reports) =
[
for (i = pts, report = reports, pt = report[3])
if (vnf[0][i] == pt) 1
] == [];
function _edge_not_reported(edge, vnf, reports) =
let(
edge = sort([for (i=edge) vnf[0][i]])
) [
for (report = reports) let(
pts = sort(report[3])
) if (len(pts)==2 && edge == pts) 1
] == [];
module vnf_validate(vnf, size=1, show_warns=true, check_isects=false) {
faults = vnf_validate(
vnf, show_warns=show_warns,
check_isects=check_isects
);
for (fault = faults) {
typ = fault[0];
err = fault[1];
msg = fault[2];
pts = fault[3];
clr = fault[4];
echo(str(typ, " ", err, ": ", msg, " at ", pts));
color(clr) {
if (len(pts)==2) {
stroke(pts, width=size);
} else if (len(pts)>2) {
stroke(pts, width=size, closed=true);
polyhedron(pts,[[for (i=idx(pts)) i]]);
} else {
move_copies(pts) sphere(d=size*3, $fn=18);
}
}
}
color([0.5,0.5,0.5,0.5]) vnf_polyhedron(vnf);
}
// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap