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rewrote check_and_fix_path. Old version was broken/undef errors

Browse source 
added regions_equal (but probably not best version)
removed debug echo from roundinglscad
assert on invalid arc() radius inpu
new "fast_distance" method for skin()
tweaked skin() docs
support regions for path_sweep
This commit is contained in:
Adrian Mariano 2021-03-12 18:40:24 -05:00
parent 6f9ea55bc8
commit f90e89c761
4 changed files with 134 additions and 42 deletions
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93
regions.scad
View file

@ -58,35 +58,34 @@ module region(r)
// Function: check_and_fix_path()
// Usage:
// check_and_fix_path(path, [valid_dim], [closed])
// check_and_fix_path(path, [valid_dim], [closed], [name])
// Description:
// Checks that the input is a path. If it is a region with one component, converts it to a path.
// Note that arbitrary paths must have at least two points, but closed paths need at least 3 points.
// valid_dim specfies the allowed dimension of the points in the path.
// If the path is closed, removed duplicate endpoint if present.
// If the path is closed, removes duplicate endpoint if present.
// Arguments:
// path = path to process
// valid_dim = list of allowed dimensions for the points in the path, e.g. [2,3] to require 2 or 3 dimensional input. If left undefined do not perform this check. Default: undef
// closed = set to true if the path is closed, which enables a check for endpoint duplication
function check_and_fix_path(path, valid_dim=undef, closed=false) =
// name = parameter name to use for reporting errors. Default: "path"
function check_and_fix_path(path, valid_dim=undef, closed=false, name="path") =
let(
path = is_region(path)? (
assert(len(path)==1,"Region supplied as path does not have exactly one component")
path[0]
) : (
assert(is_path(path), "Input is not a path")
path
),
dim = array_dim(path)
path =
is_region(path)?
assert(len(path)==1,str("Region ",name," supplied as path does not have exactly one component"))
path[0]
:
assert(is_path(path), str("Input ",name," is not a path"))
path
)
assert(dim[0]>1,"Path must have at least 2 points")
assert(len(dim)==2,"Invalid path: path is either a list of scalars or a list of matrices")
assert(is_def(dim[1]), "Invalid path: entries in the path have variable length")
let(valid=is_undef(valid_dim) || in_list(dim[1],valid_dim))
assert(len(path)>(closed?2:1),closed?str("Closed path ",name," must have at least 3 points")
:str("Path ",name," must have at least 2 points"))
let(valid=is_undef(valid_dim) || in_list(len(path[0]),force_list(valid_dim)))
assert(
valid, str(
"The points on the path have length ",
dim[1], " but length must be ",
len(valid_dim)==1? valid_dim[0] : str("one of ",valid_dim)
"Input ",name," must has dimension ", len(path[0])," but dimension must be ",
is_list(valid_dim) ? str("one of ",valid_dim) : valid_dim
)
)
closed && approx(path[0],select(path,-1))? slice(path,0,-2) : path;
@ -223,6 +222,64 @@ function split_nested_region(region) =
) outs;
function find_first_approx(val, list, start=0, all=false, eps=EPSILON) =
all? [for (i=[start:1:len(list)-1]) if(approx(val, list[i], eps=eps)) i] :
__find_first_approx(val, list, eps=eps, i=start);
function __find_first_approx(val, list, eps, i=0) =
i >= len(list)? undef :
approx(val, list[i], eps=eps)? i :
__find_first_approx(val, list, eps=eps, i=i+1);
// Function: polygons_equal()
// Usage:
// b = polygons_equal(poly1, poly2, <eps>)
// Description:
// Returns true if the components of region1 and region2 are the same polygons
// within given epsilon tolerance.
// Arguments:
// poly1 = first polygon
// poly2 = second polygon
// eps = tolerance for comparison
// Example(NORENDER):
// polygons_equal(pentagon(r=4),
// rot(360/5, p=pentagon(r=4))); // returns true
// polygons_equal(pentagon(r=4),
// rot(90, p=pentagon(r=4))); // returns false
function polygons_equal(poly1, poly2, eps=EPSILON) =
let( l1 = len(poly1), l2 = len(poly2))
l1 != l2 ? false :
let( maybes = find_first_approx(poly1[0], poly2, eps=eps, all=true) )
maybes == []? false :
[for (i=maybes) if (__polygons_equal(poly1, poly2, eps, i)) 1] != [];
function __polygons_equal(poly1, poly2, eps, st) =
max([for(d=poly1-select(poly2,st,st-1)) d*d])<eps*eps;
// Function: regions_equal()
// Usage:
// b = regions_equal(region1, region2, <eps>)
// Description:
// Returns true if the components of region1 and region2 are the same polygons
// within given epsilon tolerance.
// Arguments:
// poly1 = first polygon
// poly2 = second polygon
// eps = tolerance for comparison
function regions_equal(region1, region2) =
assert(is_region(region1) && is_region(region2))
len(region1)==len(region2) &&
[
for (a=region1)
if (1!=sum(
[for(b=region2)
if (polygons_equal(path3d(a), path3d(b)))
1]
)
) 1
] == [];
// Section: Region Extrusion and VNFs

5
rounding.scad
View file

@ -75,7 +75,7 @@ include <structs.scad>
// circular roundovers. For continuous curvature roundovers `$fs` and `$fn` are used and `$fa` is
// ignored. Note that $fn is interpreted as the number of points on the roundover curve, which is
// not equivalent to its meaning for rounding circles because roundovers are usually small fractions
// of a circular arc. When doing continuous curvature rounding be sure to use lots of segments or the effect
// of a circular arc. As usual, $fn overrides $fs. When doing continuous curvature rounding be sure to use lots of segments or the effect
// will be hidden by the discretization. Note that if you use $fn with "smooth" then $fn points are added at each corner, even
// if the "corner" is flat, with collinear points, so this guarantees a specific output length.
//
@ -264,8 +264,7 @@ function round_corners(path, method="circle", radius, cut, joint, k, closed=true
let(
pathbit = select(path,i-1,i+1),
angle = approx(pathbit[0],pathbit[1]) || approx(pathbit[1],pathbit[2]) ? undef
: vector_angle(select(path,i-1,i+1))/2,
f=echo(angle=angle)
: vector_angle(select(path,i-1,i+1))/2
)
(!closed && (i==0 || i==len(path)-1)) ? [0] : // Force zeros at ends for non-closed
parm[i]==0 ? [0] : // If no rounding requested then don't try to compute parameters

2
shapes2d.scad
View file

@ -554,7 +554,7 @@ function arc(N, r, angle, d, cp, points, width, thickness, start, wedge=false, l
)
assert(is_vector(cp,2),"Centerpoint must be a 2d vector")
assert(angle!=0, "Arc has zero length")
assert(r>0, "Arc radius invalid")
assert(is_def(r) && r>0, "Arc radius invalid")
let(
N = max(3, is_undef(N)? ceil(segs(r)*abs(angle)/360) : N),
arcpoints = [for(i=[0:N-1]) let(theta = start + i*angle/(N-1)) r*[cos(theta),sin(theta)]+cp],

76
skin.scad
View file

@ -63,8 +63,8 @@
// Note that when dealing with continuous curves it is always better to adjust the
// sampling in your code to generate the desired sampling rather than using the `refine` argument.
// .
// You can choose from four methods for specifying alignment for incommensurate profiles.
// The available methods are `"distance"`, `"tangent"`, `"direct"` and `"reindex"`.
// You can choose from five methods for specifying alignment for incommensurate profiles.
// The available methods are `"distance"`, `"fast_distance"`, `"tangent"`, `"direct"` and `"reindex"`.
// It is useful to distinguish between continuous curves like a circle and discrete profiles
// like a hexagon or star, because the algorithms' suitability depend on this distinction.
// .
@ -87,14 +87,17 @@
// `sampling="segment"` may produce a more pleasing result. These two approaches differ only when
// the segments of your input profiles have unequal length.
// .
// The "distance" and "tangent" methods work by duplicating vertices to create
// The "distance", "fast_distance" and "tangent" methods work by duplicating vertices to create
// triangular faces. The "distance" method finds the global minimum distance method for connecting two
// profiles. This algorithm generally produces a good result when both profiles are discrete ones with
// a small number of vertices. It is computationally intensive (O(N^3)) and may be
// slow on large inputs. The resulting surfaces generally have curved faces, so be
// sure to select a sufficiently large value for `slices` and `refine`. Note that for
// this method, `sampling` must be set to `"segment"`, and hence this is the default setting.
// Using sampling by length would ignore the repeated vertices and ruin the alignment.
// Using sampling by length would ignore the repeated vertices and ruin the alignment.
// The "fast_distance" method is similar to "distance", but it makes the assumption that an edge should
// connect the first vertices of the two polygons. This reduces the run time to O(N^2) and makes
// the method usable on profiles with more points if you take care to index the inputs to match.
// .
// The `"tangent"` method generally produces good results when
// connecting a discrete polygon to a convex, finely sampled curve. It works by finding
@ -104,7 +107,9 @@
// polygon using triangular faces. Using `refine` with this method will have little effect on the model, so
// you should do it only for agreement with other profiles, and these models are linear, so extra slices also
// have no effect. For best efficiency set `refine=1` and `slices=0`. As with the "distance" method, refinement
// must be done using the "segment" sampling scheme to preserve alignment across duplicated points.
// must be done using the "segment" sampling scheme to preserve alignment across duplicated points.
// Note that the "tangent" method produces similar results to the "distance" method on curved inputs. If this
// method fails due to concavity, "fast_distance" may be a good option.
// .
// It is possible to specify `method` and `refine` as arrays, but it is important to observe
// matching rules when you do this. If a pair of profiles is connected using "tangent" or "distance"
@ -119,11 +124,11 @@
// profiles = list of 2d or 3d profiles to be skinned. (If 2d must also give `z`.)
// slices = scalar or vector number of slices to insert between each pair of profiles. Set to zero to use only the profiles you provided. Recommend starting with a value around 10.
// ---
// refine = resample profiles to this number of points per edge. Can be a list to give a refinement for each profile. Recommend using a value above 10 when using the "distance" method. Default: 1.
// sampling = sampling method to use with "direct" and "reindex" methods. Can be "length" or "segment". Ignored if any profile pair uses either the "distance" or "tangent" methods. Default: "length".
// refine = resample profiles to this number of points per edge. Can be a list to give a refinement for each profile. Recommend using a value above 10 when using the "distance" or "fast_distance" methods. Default: 1.
// sampling = sampling method to use with "direct" and "reindex" methods. Can be "length" or "segment". Ignored if any profile pair uses either the "distance", "fast_distance", or "tangent" methods. Default: "length".
// closed = set to true to connect first and last profile (to make a torus). Default: false
// caps = true to create endcap faces when closed is false. Can be a length 2 boolean array. Default is true if closed is false.
// method = method for connecting profiles, one of "distance", "tangent", "direct" or "reindex". Default: "direct".
// method = method for connecting profiles, one of "distance", "fast_distance", "tangent", "direct" or "reindex". Default: "direct".
// z = array of height values for each profile if the profiles are 2d
// convexity = convexity setting for use with polyhedron. (module only) Default: 10
// anchor = Translate so anchor point is at the origin. (module only) Default: "origin"
@ -374,7 +379,7 @@ function skin(profiles, slices, refine=1, method="direct", sampling, caps, close
assert(len(bad)==0, str("Profiles ",bad," are not a paths or have length less than 3"))
let(
profcount = len(profiles) - (closed?0:1),
legal_methods = ["direct","reindex","distance","tangent"],
legal_methods = ["direct","reindex","distance","fast_distance","tangent"],
caps = is_def(caps) ? caps :
closed ? false : true,
capsOK = is_bool(caps) || (is_list(caps) && len(caps)==2 && is_bool(caps[0]) && is_bool(caps[1])),
@ -402,7 +407,7 @@ function skin(profiles, slices, refine=1, method="direct", sampling, caps, close
assert(methodlistok==[], str("method list contains invalid method at ",methodlistok))
assert(len(method) == profcount,"Method list is the wrong length")
assert(in_list(sampling,["length","segment"]), "sampling must be set to \"length\" or \"segment\"")
assert(sampling=="segment" || (!in_list("distance",method) && !in_list("tangent",method)), "sampling is set to \"length\" which is only allowed iwith methods \"direct\" and \"reindex\"")
assert(sampling=="segment" || (!in_list("distance",method) && !in_list("fast_distance") && !in_list("tangent",method)), "sampling is set to \"length\" which is only allowed with methods \"direct\" and \"reindex\"")
assert(capsOK, "caps must be boolean or a list of two booleans")
assert(!closed || !caps, "Cannot make closed shape with caps")
let(
@ -449,6 +454,7 @@ function skin(profiles, slices, refine=1, method="direct", sampling, caps, close
let(
pair =
method[i]=="distance" ? _skin_distance_match(profiles[i],select(profiles,i+1)) :
method[i]=="fast_distance" ? _skin_aligned_distance_match(profiles[i], select(profiles,i+1)) :
method[i]=="tangent" ? _skin_tangent_match(profiles[i],select(profiles,i+1)) :
/*method[i]=="reindex" || method[i]=="direct" ?*/
let( p1 = subdivide_path(profiles[i],max_list[i], method=sampling),
@ -720,6 +726,23 @@ function _skin_distance_match(poly1,poly2) =
)
swap ? [newbig, newsmall] : [newsmall,newbig];
// This function associates vertices but with the assumption that index 0 is associated between the
// two inputs. This gives only quadratic run time. As above, output is pair of polygons with
// vertices duplicated as suited to use as input to skin().
function _skin_aligned_distance_match(poly1, poly2) =
let(
result = _dp_distance_array(poly1, poly2, abort_thresh=1/0),
map = _dp_extract_map(result[1]),
shift0 = len(map[0]) - max(max_index(map[0],all=true))-1,
shift1 = len(map[1]) - max(max_index(map[1],all=true))-1,
new0 = polygon_shift(repeat_entries(poly1,unique_count(map[0])[1]),shift0),
new1 = polygon_shift(repeat_entries(poly2,unique_count(map[1])[1]),shift1)
)
[new0,new1];
//////////////////////////////////////////////////////////////////////////////////////////////////////////////
/// Internal Function: _skin_tangent_match()
/// Usage:
@ -927,7 +950,7 @@ module sweep(shape, transforms, closed=false, caps, convexity=10,
// path_sweep(shape, path, <method>, <normal=>, <closed=>, <twist=>, <twist_by_length=>, <symmetry=>, <last_normal=>, <tangent=>, <relaxed=>, <caps=>, <convexity=>, <transforms=>, <anchor=>, <cp=>, <spin=>, <orient=>, <extent=>) <attachments>;
// vnf = path_sweep(shape, path, <method>, <normal=>, <closed=>, <twist=>, <twist_by_length=>, <symmetry=>, <last_normal=>, <tangent=>, <relaxed=>, <caps=>, <convexity=>, <transforms=>);
// Description:
// Takes as input a 2D polygon path or region, and a 2d or 3d path and constructs a polyhedron by sweeping the shape along the path.
// Takes as input a 2D polygon path, and a 2d or 3d path and constructs a polyhedron by sweeping the shape along the path.
// When run as a module returns the polyhedron geometry. When run as a function returns a VNF by default or if you set `transforms=true`
// then it returns a list of transformations suitable as input to `sweep`.
// .
@ -1206,6 +1229,18 @@ module sweep(shape, transforms, closed=false, caps, convexity=10,
// outside = [for(i=[0:len(trans)-1]) trans[i]*scale(lerp(1,1.5,i/(len(trans)-1)))];
// inside = [for(i=[len(trans)-1:-1:0]) trans[i]*scale(lerp(1.1,1.4,i/(len(trans)-1)))];
// sweep(shape, concat(outside,inside),closed=true);
// Example: Using path_sweep on a region
// rgn1 = [for (d=[10:10:60]) circle(d=d,$fn=8)];
// rgn2 = [square(30,center=false)];
// rgn3 = [for (size=[10:10:20]) move([15,15],p=square(size=size, center=true))];
// mrgn = union(rgn1,rgn2);
// orgn = difference(mrgn,rgn3);
// path_sweep(orgn,arc(r=40,angle=180));
// Example: A region with a twist
// region = [for(i=pentagon(5)) move(i,p=circle(r=2,$fn=25))];
// path_sweep(region,
// circle(r=16,$fn=75),closed=true,
// twist=360/5*2,symmetry=5);
module path_sweep(shape, path, method="incremental", normal, closed=false, twist=0, twist_by_length=true,
symmetry=1, last_normal, tangent, relaxed=false, caps, convexity=10,
anchor="origin",cp,spin=0, orient=UP, extent=false)
@ -1225,7 +1260,7 @@ function path_sweep(shape, path, method="incremental", normal, closed=false, twi
assert(!closed || twist % (360/symmetry)==0, str("For a closed sweep, twist must be a multiple of 360/symmetry = ",360/symmetry))
assert(closed || symmetry==1, "symmetry must be 1 when closed is false")
assert(is_integer(symmetry) && symmetry>0, "symmetry must be a positive integer")
assert(is_path(shape,2) || is_region(shape), "shape must be a 2d path or region.")
// let(shape = check_and_fix_path(shape,valid_dim=2,closed=true,name="shape"))
assert(is_path(path), "input path is not a path")
assert(!closed || !approx(path[0],select(path,-1)), "Closed path includes start point at the end")
let(
@ -1301,15 +1336,15 @@ function path_sweep(shape, path, method="incremental", normal, closed=false, twi
translate(path[i%L])*rotation*zrot(-twist*pathfrac[i])
] :
assert(false,"Unknown method or no method given")[], // unknown method
ends_match = !closed ? true :
let(
start = apply(transform_list[0],path3d(shape)),
end = reindex_polygon(start, apply(transform_list[L],path3d(shape)))
)
all([for(i=idx(start)) approx(start[i],end[i])]),
ends_match = !closed ? true
: let( rshape = is_path(shape) ? [path3d(shape)]
: [for(s=shape) path3d(s)]
)
regions_equal(apply(transform_list[0], rshape),
apply(transform_list[L], rshape)),
dummy = ends_match ? 0 : echo("WARNING: ***** The points do not match when closing the model *****")
)
transforms ? transform_list : sweep(clockwise_polygon(shape), transform_list, closed=false, caps=fullcaps);
transforms ? transform_list : sweep(is_path(shape)?clockwise_polygon(shape):shape, transform_list, closed=false, caps=fullcaps);
// Function&Module: path_sweep2d()
@ -1361,7 +1396,8 @@ function path_sweep2d(shape, path, closed=false, caps, quality=1) =
caps = is_def(caps) ? caps
: closed ? false : true,
capsOK = is_bool(caps) || (is_list(caps) && len(caps)==2 && is_bool(caps[0]) && is_bool(caps[1])),
fullcaps = is_bool(caps) ? [caps,caps] : caps
fullcaps = is_bool(caps) ? [caps,caps] : caps,
shape = check_and_fix_path(shape,valid_dim=2,closed=true,name="shape")
)
assert(capsOK, "caps must be boolean or a list of two booleans")
assert(!closed || !caps, "Cannot make closed shape with caps")