BOSL2/paths.scad

//////////////////////////////////////////////////////////////////////
// LibFile: paths.scad
//   Polylines, polygons and paths.
//   To use, add the following lines to the beginning of your file:
//   ```
//   include <BOSL2/std.scad>
//   ```
//////////////////////////////////////////////////////////////////////


include <BOSL2/triangulation.scad>


// Section: Functions


// Function: simplify2d_path()
// Description:
//   Takes a 2D polyline and removes unnecessary collinear points.
// Usage:
//   simplify2d_path(path, [eps])
// Arguments:
//   path = A list of 2D path points.
//   eps = Largest angle delta between segments to count as colinear.  Default: 1e-6
function simplify2d_path(path, eps=1e-6) = simplify_path(path, eps=eps);


// Function: simplify3d_path()
// Description:
//   Takes a 3D polyline and removes unnecessary collinear points.
// Usage:
//   simplify3d_path(path, [eps])
// Arguments:
//   path = A list of 3D path points.
//   eps = Largest angle delta between segments to count as colinear.  Default: 1e-6
function simplify3d_path(path, eps=1e-6) = simplify_path(path, eps=eps);


// Function: path_length()
// Usage:
//   path3d_length(path)
// Description:
//   Returns the length of the path.
// Arguments:
//   path = The list of points of the path to measure.
// Example:
//   path = [[0,0], [5,35], [60,-25], [80,0]];
//   echo(path_length(path));
function path_length(path) =
	len(path)<2? 0 :
	sum([for (i = [0:1:len(path)-2]) norm(path[i+1]-path[i])]);


// Function: path3d_spiral()
// Description:
//   Returns a 3D spiral path.
// Usage:
//   path3d_spiral(turns, h, n, r|d, [cp], [scale]);
// Arguments:
//   h = Height of spiral.
//   turns = Number of turns in spiral.
//   n = Number of spiral sides.
//   r = Radius of spiral.
//   d = Radius of spiral.
//   cp = Centerpoint of spiral. Default: `[0,0]`
//   scale = [X,Y] scaling factors for each axis.  Default: `[1,1]`
// Example(3D):
//   trace_polyline(path3d_spiral(turns=2.5, h=100, n=24, r=50), N=1, showpts=true);
function path3d_spiral(turns=3, h=100, n=12, r=undef, d=undef, cp=[0,0], scale=[1,1]) = let(
		rr=get_radius(r=r, d=d, dflt=100),
		cnt=floor(turns*n),
		dz=h/cnt
	) [
		for (i=[0:1:cnt]) [
			rr * cos(i*360/n) * scale.x + cp.x,
			rr * sin(i*360/n) * scale.y + cp.y,
			i*dz
		]
	];


// Function: points_along_path3d()
// Usage:
//   points_along_path3d(polyline, path);
// Description:
//   Calculates the vertices needed to create a `polyhedron()` of the
//   extrusion of `polyline` along `path`.  The closed 2D path shold be
//   centered on the XY plane. The 2D path is extruded perpendicularly
//   along the 3D path.  Produces a list of 3D vertices.  Vertex count
//   is `len(polyline)*len(path)`.  Gives all the reoriented vertices
//   for `polyline` at the first point in `path`, then for the second,
//   and so on.
// Arguments:
//   polyline = A closed list of 2D path points.
//   path = A list of 3D path points.
function points_along_path3d(
	polyline,  // The 2D polyline to drag along the 3D path.
	path,  // The 3D polyline path to follow.
	q=Q_Ident(),  // Used in recursion
	n=0  // Used in recursion
) = let(
	end = len(path)-1,
	v1 = (n == 0)?  [0, 0, 1] : normalize(path[n]-path[n-1]),
	v2 = (n == end)? normalize(path[n]-path[n-1]) : normalize(path[n+1]-path[n]),
	crs = cross(v1, v2),
	axis = norm(crs) <= 0.001? [0, 0, 1] : crs,
	ang = vector_angle(v1, v2),
	hang = ang * (n==0? 1.0 : 0.5),
	hrot = Quat(axis, hang),
	arot = Quat(axis, ang),
	roth = Q_Mul(hrot, q),
	rotm = Q_Mul(arot, q)
) concat(
	[for (i = [0:1:len(polyline)-1]) Q_Rot_Vector(point3d(polyline[i]),roth) + path[n]],
	(n == end)? [] : points_along_path3d(polyline, path, rotm, n+1)
);



// Section: 2D Modules


// Module: modulated_circle()
// Description:
//   Creates a 2D polygon circle, modulated by one or more superimposed sine waves.
// Arguments:
//   r = radius of the base circle.
//   sines = array of [amplitude, frequency] pairs, where the frequency is the number of times the cycle repeats around the circle.
// Example(2D):
//   modulated_circle(r=40, sines=[[3, 11], [1, 31]], $fn=6);
module modulated_circle(r=40, sines=[10])
{
	freqs = len(sines)>0? [for (i=sines) i[1]] : [5];
	points = [
		for (a = [0 : (360/segs(r)/max(freqs)) : 360])
			let(nr=r+sum_of_sines(a,sines)) [nr*cos(a), nr*sin(a)]
	];
	polygon(points);
}


// Section: 3D Modules


// Module: extrude_from_to()
// Description:
//   Extrudes a 2D shape between the points pt1 and pt2.  Takes as children a set of 2D shapes to extrude.
// Arguments:
//   pt1 = starting point of extrusion.
//   pt2 = ending point of extrusion.
//   convexity = max number of times a line could intersect a wall of the 2D shape being extruded.
//   twist = number of degrees to twist the 2D shape over the entire extrusion length.
//   scale = scale multiplier for end of extrusion compared the start.
//   slices = Number of slices along the extrusion to break the extrusion into.  Useful for refining `twist` extrusions.
// Example(FlatSpin):
//   extrude_from_to([0,0,0], [10,20,30], convexity=4, twist=360, scale=3.0, slices=40) {
//       xspread(3) circle(3, $fn=32);
//   }
module extrude_from_to(pt1, pt2, convexity=undef, twist=undef, scale=undef, slices=undef) {
	rtp = xyz_to_spherical(pt2-pt1);
	translate(pt1) {
		rotate([0, rtp[2], rtp[1]]) {
			linear_extrude(height=rtp[0], convexity=convexity, center=false, slices=slices, twist=twist, scale=scale) {
				children();
			}
		}
	}
}



// Module: spiral_sweep()
// Description:
//   Takes a closed 2D polyline path, centered on the XY plane, and
//   extrudes it along a 3D spiral path of a given radius, height and twist.
// Arguments:
//   polyline = Array of points of a polyline path, to be extruded.
//   h = height of the spiral to extrude along.
//   r = radius of the spiral to extrude along.
//   twist = number of degrees of rotation to spiral up along height.
//   anchor = Translate so anchor point is at origin (0,0,0).  See [anchor](attachments.scad#anchor).  Default: `CENTER`
//   spin = Rotate this many degrees around the Z axis after anchor.  See [spin](attachments.scad#spin).  Default: `0`
//   orient = Vector to rotate top towards, after spin.  See [orient](attachments.scad#orient).  Default: `UP`
//   center = If given, overrides `anchor`.  A true value sets `anchor=CENTER`, false sets `anchor=BOTTOM`.
// Example:
//   poly = [[-10,0], [-3,-5], [3,-5], [10,0], [0,-30]];
//   spiral_sweep(poly, h=200, r=50, twist=1080, $fn=36);
module spiral_sweep(polyline, h, r, twist=360, center=undef, anchor=BOTTOM, spin=0, orient=UP) {
	pline_count = len(polyline);
	steps = ceil(segs(r)*(twist/360));

	poly_points = [
		for (
			p = [0:1:steps]
		) let (
			a = twist * (p/steps),
			dx = r*cos(a),
			dy = r*sin(a),
			dz = h * (p/steps),
			pts = affine3d_apply(
				polyline, [
					affine3d_xrot(90),
					affine3d_zrot(a),
					affine3d_translate([dx, dy, dz-h/2])
				]
			)
		) for (pt = pts) pt
	];

	poly_faces = concat(
		[[for (b = [0:1:pline_count-1]) b]],
		[
			for (
				p = [0:1:steps-1],
				b = [0:1:pline_count-1],
				i = [0:1]
			) let (
				b2 = (b == pline_count-1)? 0 : b+1,
				p0 = p * pline_count + b,
				p1 = p * pline_count + b2,
				p2 = (p+1) * pline_count + b2,
				p3 = (p+1) * pline_count + b,
				pt = (i==0)? [p0, p2, p1] : [p0, p3, p2]
			) pt
		],
		[[for (b = [pline_count-1:-1:0]) b+(steps)*pline_count]]
	);

	tri_faces = triangulate_faces(poly_points, poly_faces);
	orient_and_anchor([r,r,h], orient, anchor, spin=spin, center=center, geometry="cylinder", chain=true) {
		polyhedron(points=poly_points, faces=tri_faces, convexity=10);
		children();
	}
}


// Module: path_sweep()
// Description:
//   Takes a closed 2D path `polyline`, centered on the XY plane, and extrudes it perpendicularly along a 3D path `path`, forming a solid.
// Arguments:
//   polyline = Array of points of a polyline path, to be extruded.
//   path = Array of points of a polyline path, to extrude along.
//   ang = Angle in degrees to rotate 2D polyline before extrusion.
//   convexity = max number of surfaces any single ray could pass through.
// Example(FlatSpin):
//   shape = [[0,-10], [5,-3], [5,3], [0,10], [30,0]];
//   path = concat(
//       [for (a=[30:30:180]) [50*cos(a)+50, 50*sin(a), 20*sin(a)]],
//       [for (a=[330:-30:180]) [50*cos(a)-50, 50*sin(a), 20*sin(a)]]
//   );
//   path_sweep(shape, path, ang=140);
module path_sweep(polyline, path, ang=0, convexity=10) {
	pline_count = len(polyline);
	path_count = len(path);

	polyline = rotate_points2d(path2d(polyline), ang);
	poly_points = points_along_path3d(polyline, path);

	poly_faces = concat(
		[[for (b = [0:1:pline_count-1]) b]],
		[
			for (
				p = [0:1:path_count-2],
				b = [0:1:pline_count-1],
				i = [0:1]
			) let (
				b2 = (b == pline_count-1)? 0 : b+1,
				p0 = p * pline_count + b,
				p1 = p * pline_count + b2,
				p2 = (p+1) * pline_count + b2,
				p3 = (p+1) * pline_count + b,
				pt = (i==0)? [p0, p2, p1] : [p0, p3, p2]
			) pt
		],
		[[for (b = [pline_count-1:-1:0]) b+(path_count-1)*pline_count]]
	);

	tri_faces = triangulate_faces(poly_points, poly_faces);
	polyhedron(points=poly_points, faces=tri_faces, convexity=convexity);
}



// Module: path_extrude()
// Description:
//   Extrudes 2D children along a 3D polyline path.  This may be slow.
// Arguments:
//   path = array of points for the bezier path to extrude along.
//   convexity = maximum number of walls a ran can pass through.
//   clipsize = increase if artifacts are left.  Default: 1000
// Example(FlatSpin):
//   path = [ [0, 0, 0], [33, 33, 33], [66, 33, 40], [100, 0, 0], [150,0,0] ];
//   path_extrude(path) circle(r=10, $fn=6);
module path_extrude(path, convexity=10, clipsize=100) {
	function polyquats(path, q=Q_Ident(), v=[0,0,1], i=0) = let(
			v2 = path[i+1] - path[i],
			ang = vector_angle(v,v2),
			axis = ang>0.001? normalize(cross(v,v2)) : [0,0,1],
			newq = Q_Mul(Quat(axis, ang), q),
			dist = norm(v2)
		) i < (len(path)-2)?
			concat([[dist, newq, ang]], polyquats(path, newq, v2, i+1)) :
			[[dist, newq, ang]];

	epsilon = 0.0001;  // Make segments ever so slightly too long so they overlap.
	ptcount = len(path);
	pquats = polyquats(path);
	for (i = [0:1:ptcount-2]) {
		pt1 = path[i];
		pt2 = path[i+1];
		dist = pquats[i][0];
		q = pquats[i][1];
		difference() {
			translate(pt1) {
				Qrot(q) {
					down(clipsize/2/2) {
						linear_extrude(height=dist+clipsize/2, convexity=convexity) {
							children();
						}
					}
				}
			}
			translate(pt1) {
				hq = (i > 0)? Q_Slerp(q, pquats[i-1][1], 0.5) : q;
				Qrot(hq) down(clipsize/2+epsilon) cube(clipsize, center=true);
			}
			translate(pt2) {
				hq = (i < ptcount-2)? Q_Slerp(q, pquats[i+1][1], 0.5) : q;
				Qrot(hq) up(clipsize/2+epsilon) cube(clipsize, center=true);
			}
		}
	}
}


// Module: trace_polyline()
// Description:
//   Renders lines between each point of a polyline path.
//   Can also optionally show the individual vertex points.
// Arguments:
//   pline = The array of points in the polyline.
//   showpts = If true, draw vertices and control points.
//   N = Mark the first and every Nth vertex after in a different color and shape.
//   size = Diameter of the lines drawn.
//   color = Color to draw the lines (but not vertices) in.
// Example(FlatSpin):
//   polyline = [for (a=[0:30:210]) 10*[cos(a), sin(a), sin(a)]];
//   trace_polyline(polyline, showpts=true, size=0.5, color="lightgreen");
module trace_polyline(pline, showpts=false, N=1, size=1, color="yellow") {
	sides = segs(size/2);
	if (showpts) {
		for (i = [0:1:len(pline)-1]) {
			translate(pline[i]) {
				if (i%N == 0) {
					color("blue") sphere(d=size*2.5, $fn=8);
				} else {
					color("red") {
						cylinder(d=size/2, h=size*3, center=true, $fn=8);
						xrot(90) cylinder(d=size/2, h=size*3, center=true, $fn=8);
						yrot(90) cylinder(d=size/2, h=size*3, center=true, $fn=8);
					}
				}
			}
		}
	}
	if (N!=3) {
		path_sweep(circle(d=size,$fn=sides), path3d(pline));
	} else {
		for (i = [0:1:len(pline)-2]) {
			if (N!=3 || (i%N) != 1) {
				color(color) extrude_from_to(pline[i], pline[i+1]) circle(d=size, $fn=sides);
			}
		}
	}
}


// Module: debug_polygon()
// Description: A drop-in replacement for `polygon()` that renders and labels the path points.
// Arguments:
//   points = The array of 2D polygon vertices.
//   paths = The path connections between the vertices.
//   convexity = The max number of walls a ray can pass through the given polygon paths.
// Example(Big2D):
//   debug_polygon(
//       points=concat(
//           regular_ngon(or=10, n=8),
//           regular_ngon(or=8, n=8)
//       ),
//       paths=[
//           [for (i=[0:7]) i],
//           [for (i=[15:-1:8]) i]
//       ]
//   );
module debug_polygon(points, paths=undef, convexity=2, size=1)
{
	pths = is_undef(paths)? [for (i=[0:1:len(points)-1]) i] : is_num(paths[0])? [paths] : paths;
	echo(points=points);
	echo(paths=paths);
	linear_extrude(height=0.01, convexity=convexity, center=true) {
		polygon(points=points, paths=paths, convexity=convexity);
	}
	for (i = [0:1:len(points)-1]) {
		color("red") {
			up(0.2) {
				translate(points[i]) {
					linear_extrude(height=0.1, convexity=10, center=true) {
						text(text=str(i), size=size, halign="center", valign="center");
					}
				}
			}
		}
	}
	for (j = [0:1:len(paths)-1]) {
		path = paths[j];
		translate(points[path[0]]) {
			color("cyan") up(0.1) cylinder(d=size*1.5, h=0.01, center=false, $fn=12);
		}
		translate(points[path[len(path)-1]]) {
			color("pink") up(0.11) cylinder(d=size*1.5, h=0.01, center=false, $fn=4);
		}
		for (i = [0:1:len(path)-1]) {
			midpt = (points[path[i]] + points[path[(i+1)%len(path)]])/2;
			color("blue") {
				up(0.2) {
					translate(midpt) {
						linear_extrude(height=0.1, convexity=10, center=true) {
							text(text=str(chr(65+j),i), size=size/2, halign="center", valign="center");
						}
					}
				}
			}
		}
	}
}



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