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Added keep_corners= to resample_path()

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Revar Desmera 2023-09-11 18:28:25 -07:00
parent b904ca6f19
commit 82de139057
3 changed files with 62 additions and 28 deletions
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12
gears.scad
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@ -2395,7 +2395,7 @@ function enveloping_worm(
assert(is_finite(gear_spin))
let(
hsteps = segs(d/2),
vsteps = hsteps*3,
vsteps = hsteps,
helical = asin(starts * circ_pitch / PI / d),
pr = pitch_radius(circ_pitch, mate_teeth, helical=helical),
taper_table = taper
@ -2647,11 +2647,11 @@ function worm_gear(
u = i / oslices,
w_ang = worm_arc * (u - 0.5),
g_ang_delta = w_ang/360 * tang * worm_starts * (left_handed?1:-1),
m = zrot(dir*(rteeth-0.0)*tang, cp=[worm_diam/2+pr,0,0]) *
m = zrot(dir*rteeth*tang+g_ang_delta, cp=[worm_diam/2+pr,0,0]) *
left(crowning) *
yrot(w_ang) *
right(worm_diam/2+crowning) *
zrot(-1*dir*(rteeth+0.0)*tang+g_ang_delta, cp=[pr,0,0]) *
zrot(-dir*rteeth*tang+g_ang_delta, cp=[pr,0,0]) *
xrot(180)
) apply(m, point3d(pt))
]
@ -2674,7 +2674,7 @@ function worm_gear(
twang1 = v_theta(truncrows[0][0]),
twang2 = v_theta(last(truncrows[0])),
twang = modang(twang1 - twang2) / (maxz-minz),
resampled_rows = [for (row = truncrows) resample_path(row, n=slices, closed=false)],
resampled_rows = [for (row = truncrows) resample_path(row, n=slices, keep_corners=30, closed=false)],
tooth_rows = [
for (row = resampled_rows) [
zrot(twang*(zmax-row[0].z), p=[row[0].x, row[0].y, zmax]),
@ -2963,7 +2963,7 @@ function _gear_tooth_profile(
// Reduce number of vertices.
tooth = path_merge_collinear(
resample_path(full_tooth, n=ceil(2*steps), closed=false)
resample_path(full_tooth, n=ceil(2*steps), keep_corners=30, closed=false)
),
out = center? fwd(prad, p=tooth) : tooth
@ -3944,7 +3944,7 @@ module _show_gear_tooth_profile(
stroke([polar_to_xy(min(rr,br)-mod/10,90+180/teeth),polar_to_xy(or+mod/10,90+180/teeth)], width=0.05, closed=true);
}
zrot_copies([0]) { // Tooth profile overlay
stroke(tooth, width=0.1, dots=(show_verts?"dot":false), endcap_color1="green");
stroke(tooth, width=0.1, dots=(show_verts?"dot":false), endcap_color1="green", endcap_color2="red");
}
}
}

4
geometry.scad
View file

@ -168,14 +168,14 @@ function is_collinear(a, b, c, eps=EPSILON) =
// Topics: Geometry, Points, Lines, Distance
// See Also: is_collinear(), is_point_on_line(), point_line_distance(), line_from_points()
// Usage:
// dist = point_line_distance(line, pt, [bounded]);
// dist = point_line_distance(pt, line, [bounded]);
// Description:
// Finds the shortest distance from the point `pt` to the specified line, segment or ray.
// The bounded parameter specifies the whether the endpoints give a ray or segment.
// By default assumes an unbounded line.
// Arguments:
// line = A list of two points defining a line.
// pt = A point to find the distance of from the line.
// line = A list of two points defining a line.
// bounded = a boolean or list of two booleans specifiying whether each end is bounded. Default: false
// Example:
// dist1 = point_line_distance([3,8], [[-10,0], [10,0]]); // Returns: 8

74
paths.scad
View file

@ -473,7 +473,8 @@ function subdivide_path(path, n, refine, maxlen, closed=true, exact, method) =
// Description:
// Compute a uniform resampling of the input path. If you specify `n` then the output path will have n
// points spaced uniformly (by linear interpolation along the input path segments). The only points of the
// input path that are guaranteed to appear in the output path are the starting and ending points.
// input path that are guaranteed to appear in the output path are the starting and ending points, and any
// points that have an angular deflection of at least the number of degrees given in `keep_corners`.
// If you specify `spacing` then the length you give will be rounded to the nearest spacing that gives
// a uniform sampling of the path and the resulting uniformly sampled path is returned.
// Note that because this function operates on a discrete input path the quality of the output depends on
@ -483,6 +484,7 @@ function subdivide_path(path, n, refine, maxlen, closed=true, exact, method) =
// n = Number of points in output
// ---
// spacing = Approximate spacing desired
// keep_corners = If given a scalar, path vertices with deflection angle greater than this are preserved in the output.
// closed = set to true if path is closed. Default: true
// Example(2D): Subsampling lots of points from a smooth curve
// path = xscale(2,circle($fn=250, r=10));
@ -494,35 +496,67 @@ function subdivide_path(path, n, refine, maxlen, closed=true, exact, method) =
// sampled = resample_path(path, spacing=17);
// stroke(path);
// color("red")move_copies(sampled) circle($fn=16);
// Example(2D): Notice that the corners are excluded
// Example(2D): Notice that the corners are excluded.
// path = square(20);
// sampled = resample_path(path, spacing=6);
// stroke(path,closed=true);
// color("red")move_copies(sampled) circle($fn=16);
// Example(2D): Forcing preservation of corners.
// path = square(20);
// sampled = resample_path(path, spacing=6, keep_corners=90);
// stroke(path,closed=true);
// color("red")move_copies(sampled) circle($fn=16);
// Example(2D): Closed set to false
// path = square(20);
// sampled = resample_path(path, spacing=6,closed=false);
// stroke(path);
// color("red")move_copies(sampled) circle($fn=16);
function resample_path(path, n, spacing, closed=true) =
let(path = force_path(path))
assert(is_path(path))
assert(num_defined([n,spacing])==1,"Must define exactly one of n and spacing")
assert(is_bool(closed))
let(
length = path_length(path,closed),
// In the open path case decrease n by 1 so that we don't try to get
// path_cut to return the endpoint (which might fail due to rounding)
// Add last point later
n = is_def(n) ? n-(closed?0:1) : round(length/spacing),
distlist = lerpn(0,length,n,false),
cuts = path_cut_points(path, distlist, closed=closed)
)
[ each column(cuts,0),
if (!closed) last(path) // Then add last point here
];
function resample_path(path, n, spacing, keep_corners, closed=true) =
let(path = force_path(path))
assert(is_path(path))
assert(num_defined([n,spacing])==1,"Must define exactly one of n and spacing")
assert(n==undef || (is_integer(n) && n>0))
assert(spacing==undef || (is_finite(spacing) && spacing>0))
assert(is_bool(closed))
let(
corners = is_undef(keep_corners)
? [0, len(path)-(closed?0:1)]
: [
0,
for (i = [1:1:len(path)-(closed?1:2)])
let( ang = abs(modang(vector_angle(select(path,i-1,i+1))-180)) )
if (ang >= keep_corners) i,
len(path)-(closed?0:1),
],
pcnt = len(path),
plen = path_length(path, closed=closed),
subpaths = [ for (p = pair(corners)) [for(i = [p.x:1:p.y]) path[i%pcnt]] ],
n = is_undef(n)? n : closed? n+1 : n
)
assert(n==undef || n >= len(corners), "There are nore than `n=` corners whose angle is greater than `keep_corners=`.")
let(
lens = [for (subpath = subpaths) path_length(subpath)],
part_ns = is_undef(n)
? [for (i=idx(subpaths)) ceil(lens[i]/spacing)-1]
: let(
ccnt = len(corners),
parts = [for (l=lens) (n-ccnt) * l/plen],
)
_sum_preserving_round(parts),
out = [
for (i = idx(subpaths))
let(
subpath = subpaths[i],
splen = lens[i],
n = part_ns[i] + 1,
distlist = lerpn(0, splen, n, false),
cuts = path_cut_points(subpath, distlist, closed=false)
)
each column(cuts,0),
if (!closed) last(path)
]
) out;
// Section: Path Geometry