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Fix problem with face vertex order.

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This commit is contained in:
Adrian Mariano 2021-04-07 16:20:54 -04:00
parent ca29e2ef87
commit ed2daac8c2
1 changed files with 30 additions and 14 deletions
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polyhedra.scad
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@ -147,7 +147,7 @@ function _unique_groups(m) = [
// Side Effects:
// `$faceindex` - Index number of the face
// `$face` - Coordinates of the face (2d if rotate_children==true, 3d if not)
// `$center` - Polyhedron center in the child coordinate system
// `$center` - Face center in the child coordinate system
//
// Examples: All of the available polyhedra by name in their native orientation
// regular_polyhedron("tetrahedron", facedown=false);
@ -275,6 +275,10 @@ function _unique_groups(m) = [
// %sphere(r=.98);
// regular_polyhedron("pentagonal hexecontahedron", or=1,facedown=false);
// }
// Example: Stellate an Archimedian solid, which has mixed faces
// regular_polyhedron("truncated icosahedron",stellate=1.5,or=1);
// Example: Stellate a Catalan solid where faces are not regular
// regular_polyhedron("triakis tetrahedron",stellate=0.5,or=1);
module regular_polyhedron(
name=undef,
index=undef,
@ -330,20 +334,19 @@ module regular_polyhedron(
}
}
}
translate(translation)
if ($children>0) {
maxrange = repeat ? len(faces)-1 : $children-1;
for(i=[0:1:maxrange]) {
// Would like to orient so an edge (longest edge?) is parallel to x axis
facepts = move(translation, p=select(scaled_points, faces[i]));
center = mean(facepts);
rotatedface = rot(from=face_normals[i], to=[0,0,1], p=move(-center, p=facepts));
clockwise = sortidx([for(pt=rotatedface) -atan2(pt.y,pt.x)]);
$face = rotate_children?
path2d(select(rotatedface,clockwise)) :
select(move(-center,p=facepts), clockwise);
facepts = select(scaled_points, faces[i]);
$center = -mean(facepts);
cfacepts = move($center, p=facepts);
$face = rotate_children
? path2d(rot(from=face_normals[i], to=[0,0,1], p=cfacepts))
: cfacepts;
$faceindex = i;
$center = -translation-center;
translate(center)
translate(-$center)
if (rotate_children) {
rot(from=[0,0,1], to=face_normals[i])
children(i % $children);
@ -699,7 +702,7 @@ function regular_polyhedron_info(
face_normals,
radius_scale*entry[in_radius]
] :
info == "vnf" ? [move(translation,p=scaled_points), stellate ? faces : face_triangles] :
info == "vnf" ? [move(translation,p=scaled_points), faces] :
info == "vertices" ? move(translation,p=scaled_points) :
info == "faces" ? faces :
info == "face normals" ? face_normals :
@ -770,15 +773,28 @@ function _facenormal(pts, face) = unit(cross(pts[face[2]]-pts[face[0]], pts[face
// hull() function returns triangulated faces. This function identifies the vertices that belong to each face
// by grouping together the face triangles that share normal vectors. The output gives the face polygon
// point indices in arbitrary order (not usable as input to a polygon call) and a normal vector.
// point indices in arbitrary order (not usable as input to a polygon call) and a normal vector. Finally
// the faces are ordered based on angle with their center (will always give a valid order for convex polygons).
// Final return is [ordered_faces, facenormals] where the first is a list of indices into the point list
// and the second is a list of vectors.
function _full_faces(pts,faces) =
let(
normals = [for(face=faces) quant(_facenormal(pts,face),1e-12)],
groups = _unique_groups(normals),
faces = [for(entry=groups) unique(flatten(select(faces, entry)))],
facenormals = [for(entry=groups) normals[entry[0]]]
) [faces, facenormals];
facenormals = [for(entry=groups) normals[entry[0]]],
ordered_faces = [
for(i=idx(faces))
let(
facepts = select(pts, faces[i]),
center = mean(facepts),
rotatedface = rot(from=facenormals[i], to=[0,0,1], p=move(-center, p=facepts)),
clockwise = sortidx([for(pt=rotatedface) -atan2(pt.y,pt.x)])
)
select(faces[i],clockwise)
]
) [ordered_faces, facenormals];
// vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap