First pass at attachments support.

constants.scad

@@ -342,5 +342,20 @@ function corner_edge_count(edges, v) =
 	);
 
 
+// Default values for attachment code.
+$color = undef;
+$overlap = 0.01;
+$attach_to = undef;
+$attach_conn = ["center", V_ZERO, V_UP, 0];
+$parent_size = undef;
+$parent_size2 = undef;
+$parent_shift = [0,0];
+$parent_orient = ORIENT_Z;
+$parent_align = "center";
+$parent_conns = [];
+$tags_shown = [];
+$tags_hidden = [];
+$tags = "";
+
 
 // vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

debug.scad

@@ -175,4 +175,76 @@ module debug_polyhedron(points, faces, convexity=10, txtsize=1, disabled=false)
 
 
 
+// Function: all_conns()
+// Description:
+//   Return the names for all standard connectors for a region.
+// Arguments:
+//   type = The type of region to show connectors for.  "cube", "cylinder", "sphere"
+function all_conns(type="cube") =
+	assert(in_list(type,["cube", "cylinder", "sphere"]))
+	let (
+		zs = ["top", "bottom"],
+		ys = ["front", "back"],
+		xs = ["left", "right"]
+	) concat(
+		["center"],
+		[for (a=concat(xs,ys,zs)) a],
+		in_list(type,["cube","cylinder"])? [for (a=zs, b=ys) str(a,"-",b)] : [],
+		in_list(type,["cube","cylinder"])? [for (a=zs, b=xs) str(a,"-",b)] : [],
+		in_list(type,["cube"])? [for (a=ys, b=xs) str(a,"-",b)] : [],
+		in_list(type,["cube"])? [for (a=zs, b=ys, c=xs) str(a,"-",b,"-",c)] : []
+	);
+
+
+
+// Module: connector_arrow()
+// Usage:
+//   connector_arrow([s], [color], [flag]);
+// Description:
+//   Show a connector orientation arrow.
+// Arguments:
+//   s = Length of the arrows.
+//   color = Color of the arrow.
+//   flag = If true, draw the orientation flag on the arrowhead.
+module connector_arrow(s=10, color=[0.333,0.333,1], flag=true) {
+	$fn=12;
+	recolor("gray") spheroid(d=s/6)
+	recolor(color) cyl(h=s*2/3, d=s/15, align=V_UP)
+	attach("top") cyl(h=s/3, d1=s/5, d2=0, align=V_UP) {
+		if(flag) {
+			attach("bottom") recolor([1,0.5,0.5]) cuboid([s/50, s/6, s/4], align="front-top");
+		}
+	}
+}
+
+
+
+// Module: show_connectors()
+// Description:
+//   Show all standard connectors for a given region.
+// Arguments:
+//   type = The type of region to show connectors for.  "cube", "cylinder", "sphere"
+module show_connectors(type="cube") {
+	for (conn=all_conns(type)) {
+		attach(conn) connector_arrow();
+	}
+	children();
+}
+
+
+
+// Module: frameref()
+// Description:
+//   Displays X,Y,Z axis arrows in red, green, and blue respectively.
+// Arguments:
+//   s = Length of the arrows.
+module frameref(s=15) {
+	sphere(0.001) {
+		attach("right") connector_arrow(s=s, color="red", flag=false);
+		attach("back") connector_arrow(s=s, color="green", flag=false);
+		attach("top") connector_arrow(s=s, color="blue", flag=false);
+	}
+}
+
+
 // vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

examples/attachments.scad

@@ -0,0 +1,21 @@
+include <BOSL/constants.scad>
+include <BOSL/transforms.scad>
+include <BOSL/primitives.scad>
+include <BOSL/shapes.scad>
+include <BOSL/debug.scad>
+
+cuboid([60,40,40], fillet=5, edges=EDGES_Z_ALL, align="bottom") {
+	attach("top") rounded_prismoid([60,40],[20,20], h=50, r1=5, r2=10) {
+		attach("top") cylinder(d=20, h=30) {
+			attach("top") cylinder(d1=50, d2=30, h=12);
+		}
+		for (a = ["front", "back", "left", "right"]) {
+			attach(a) cylinder(d1=14, d2=5, h=20) {
+				attach("top", "left", overlap=5) prismoid([30,20], [20,20], h=10, shift=[-7,0]);
+			}
+		}
+	}
+}
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

examples/cylinder_connectors.scad

@@ -0,0 +1,9 @@
+include <BOSL/constants.scad>
+include <BOSL/primitives.scad>
+include <BOSL/debug.scad>
+
+
+cylinder(h=30, d1=50, d2=30) show_connectors("cylinder");
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

examples/fractal_tree.scad

@@ -0,0 +1,42 @@
+include <BOSL/constants.scad>
+include <BOSL/transforms.scad>
+include <BOSL/primitives.scad>
+include <BOSL/beziers.scad>
+
+module leaf(s) {
+	path = [
+		[0,0], [1.5,-1],
+		[2,1], [0,3], [-2,1],
+		[-1.5,-1], [0,0]
+	];
+	xrot(90)
+	linear_extrude_bezier(
+		scale_points(path, [s,s]/2),
+		height=0.02
+	);
+}
+
+module branches(minsize){
+    if($parent_size2.x>minsize) {
+		attach("top")
+		zrot(gaussian_rand(90,10))
+		zring(n=floor(log_rand(2,5,4)))
+		zrot(gaussian_rand(0,5))
+		yrot(gaussian_rand(30,5))
+		let(
+			sc = gaussian_rand(0.7,0.05),
+			s1 = $parent_size.z*sc,
+			s2 = $parent_size2.x
+		)
+		cylinder(d1=s2, d2=s2*sc, l=s1)
+		branches(minsize);
+	} else {
+		recolor("springgreen")
+		attach("top") zrot(90)
+		leaf(gaussian_rand(100,5));
+	}
+}
+recolor("lightgray") cylinder(d1=300, d2=250, l=1500) branches(5);
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

examples/prismoid_connectors.scad

@@ -0,0 +1,9 @@
+include <BOSL/constants.scad>
+include <BOSL/shapes.scad>
+include <BOSL/debug.scad>
+
+
+prismoid([60,40], [30,20], h=40) show_connectors();
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

examples/tagged_diff.scad

@@ -0,0 +1,18 @@
+include <BOSL/constants.scad>
+include <BOSL/transforms.scad>
+include <BOSL/primitives.scad>
+include <BOSL/shapes.scad>
+
+
+diff("hole", "body pole")
+sphere(d=100, $tags="body") {
+	zcyl(d=55, h=100, $tags="pole");  // attach() not needed for center-to-center.
+	tags("hole") {
+		xcyl(d=55, h=101);
+		ycyl(d=55, h=101);
+	}
+	zcyl(d=15, h=140, $tags="axle");
+}
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

primitives.scad

@@ -0,0 +1,153 @@
+//////////////////////////////////////////////////////////////////////
+// LibFile: primitives.scad
+//   The basic built-in shapes, reworked to integrate better with
+//   other BOSL library shapes and utilities.
+//   To use, add the following lines to the beginning of your file:
+//   ```
+//   include <BOSL/constants.scad>
+//   use <BOSL/primitives.scad>
+//   ```
+//////////////////////////////////////////////////////////////////////
+
+/*
+BSD 2-Clause License
+
+Copyright (c) 2017, Revar Desmera
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+
+include <constants.scad>
+include <compat.scad>
+use <transforms.scad>
+use <math.scad>
+
+
+// Section: Primitive Shapes
+
+
+// Module: cube()
+//
+// Description:
+//   Creates a cube object, with support for alignment and attachments.
+//   This is a drop-in replacement for the built-in `cube()` module.
+//
+// Arguments:
+//   size = The size of the cube.
+//   align = The side of the origin to align to.  Use `V_` constants from `constants.scad`.  Default: `V_CENTER`
+//   center = If given, overrides `align`.  A true value sets `align=V_CENTER`, false sets `align=V_UP+V_BACK+V_RIGHT`.
+//
+// Example: Simple regular cube.
+//   cube(40);
+// Example: Rectangular cube, with given X, Y, and Z sizes.
+//   cuboid([20,40,50]);
+module cube(size, center=undef, align=V_ALLPOS)
+{
+	size = scalar_vec3(size);
+	orient_and_align(size, ORIENT_Z, align, center, noncentered=V_ALLPOS, chain=true) {
+		linear_extrude(height=size.z, convexity=2, center=true) {
+			square([size.x, size.y], center=true);
+		}
+		children();
+	}
+}
+
+
+// Module: cylinder()
+// Usage:
+//   cylinder(h, r|d, [center], [orient], [align]);
+//   cylinder(h, r1/d1, r2/d2, [center], [orient], [align]);
+// Description:
+//   Creates a cylinder object, with support for alignment and attachments.
+//   This is a drop-in replacement for the built-in `cylinder()` module.
+// Arguments:
+//   l / h = The height of the cylinder.
+//   r = The radius of the cylinder.
+//   r1 = The bottom radius of the cylinder.  (Before orientation.)
+//   r2 = The top radius of the cylinder.  (Before orientation.)
+//   d = The diameter of the cylinder.
+//   d1 = The bottom diameter of the cylinder.  (Before orientation.)
+//   d2 = The top diameter of the cylinder.  (Before orientation.)
+//   orient = Orientation of the cylinder.  Use the `ORIENT_` constants from `constants.scad`.  Default: vertical.
+//   align = The side of the origin to align to.  Use `V_` constants from `constants.scad`.  Default: `V_CENTER`
+//   center = If given, overrides `align`.  A true value sets `align=V_CENTER`, false sets `align=V_UP+V_BACK+V_RIGHT`.
+// Example: By Radius
+//   xdistribute(30) {
+//       cylinder(h=40, r=10);
+//       cylinder(h=40, r1=10, r2=5);
+//   }
+// Example: By Diameter
+//   xdistribute(30) {
+//       cylinder(h=40, d=25);
+//       cylinder(h=40, d1=25, d2=10);
+//   }
+module cylinder(r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h=undef, l=undef, center=undef, orient=ORIENT_Z, align=ALIGN_POS)
+{
+	r1 = get_radius(r1=r1, r=r, d1=d1, d=d, dflt=1);
+	r2 = get_radius(r1=r2, r=r, d1=d2, d=d, dflt=1);
+	l = first_defined([h, l]);
+	sides = segs(max(r1,r2));
+	size = [r1*2, r1*2, l];
+	orient_and_align(size, orient, align, center, size2=[r2*2,r2*2], noncentered=ALIGN_POS, chain=true) {
+		linear_extrude(height=l, scale=r2/r1, convexity=2, center=true) {
+			circle(r=r1, $fn=sides);
+		}
+		children();
+	}
+}
+
+
+
+// Module: sphere()
+// Usage:
+//   sphere(r|d, [orient], [align])
+// Description:
+//   Creates a sphere object, with support for alignment and attachments.
+//   This is a drop-in replacement for the built-in `sphere()` module.
+// Arguments:
+//   r = Radius of the sphere.
+//   d = Diameter of the sphere.
+//   orient = Orientation of the sphere, if you don't like where the vertices lay.  Use the `ORIENT_` constants from `constants.scad`.  Default: `ORIENT_Z`.
+//   align = Alignment of the sphere.  Use the `V_` constants from `constants.scad`.  Default: `V_CENTER`.
+// Example:
+//   staggered_sphere(d=100);
+module sphere(r=undef, d=undef, orient=ORIENT_Z, align=V_CENTER)
+{
+	r = get_radius(r=r, d=d, dflt=1);
+	sides = segs(r);
+	size = [r*2, r*2, r*2];
+	orient_and_align(size, orient, align, chain=true) {
+		rotate_extrude(convexity=2) {
+			difference() {
+				circle(r=r, $fn=sides);
+				left(r+0.1) square(r*2+0.2, center=true);
+			}
+		}
+		children();
+	}
+}
+
+
+
+// vim: noexpandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap

shapes.scad

@@ -96,26 +96,25 @@ module cuboid(
 	if (is_def(p1)) {
 		if (is_def(p2)) {
 			translate([for (v=array_zip([p1,p2],0)) min(v)]) {
-				cuboid(size=vabs(p2-p1), chamfer=chamfer, fillet=fillet, edges=edges, trimcorners=trimcorners, align=V_ALLPOS);
+				cuboid(size=vabs(p2-p1), chamfer=chamfer, fillet=fillet, edges=edges, trimcorners=trimcorners, align=V_ALLPOS) children();
 			}
 		} else {
 			translate(p1) {
-				cuboid(size=size, chamfer=chamfer, fillet=fillet, edges=edges, trimcorners=trimcorners, align=V_ALLPOS);
+				cuboid(size=size, chamfer=chamfer, fillet=fillet, edges=edges, trimcorners=trimcorners, align=V_ALLPOS) children();
 			}
 		}
 	} else {
-		majrots = [[0,90,0], [90,0,0], [0,0,0]];
 		if (chamfer != undef) assertion(chamfer <= min(size)/2, "chamfer must be smaller than half the cube width, length, or height.");
 		if (fillet != undef)  assertion(fillet <= min(size)/2, "fillet must be smaller than half the cube width, length, or height.");
-		algn = (!is_def(center))? (is_scalar(align)? align*V_UP : align) : (center==true)? V_CENTER : V_ALLPOS;
+		majrots = [[0,90,0], [90,0,0], [0,0,0]];
-		translate(vmul(size/2, algn)) {
+		orient_and_align(size, ORIENT_Z, align, center=center, noncentered=V_ALLPOS, chain=true) {
 			if (chamfer != undef) {
 				isize = [for (v = size) max(0.001, v-2*chamfer)];
 				if (edges == EDGES_ALL && trimcorners) {
 					hull() {
-						cube([size[0], isize[1], isize[2]], center=true);
+						cube([size.x, isize.y, isize.z], center=true);
-						cube([isize[0], size[1], isize[2]], center=true);
+						cube([isize.x, size.y, isize.z], center=true);
-						cube([isize[0], isize[1], size[2]], center=true);
+						cube([isize.x, isize.y, size.z], center=true);
 					}
 				} else {
 					difference() {
@@ -201,6 +200,7 @@ module cuboid(
 			} else {
 				cube(size=size, center=true);
 			}
+			children();
 		}
 	}
 }
@@ -221,7 +221,7 @@ module cuboid(
 //   p2 = Coordinate point of opposite cube corner.
 module cube2pt(p1,p2) {
 	deprecate("cube2pt()", "cuboid(p1,p2)");
-	cuboid(p1=p1, p2=p2);
+	cuboid(p1=p1, p2=p2) children();
 }
 
 
@@ -240,7 +240,7 @@ module cube2pt(p1,p2) {
 //   span_cube([0,15], [5,10], [0, 10]);
 module span_cube(xspan, yspan, zspan) {
 	span = [xspan, yspan, zspan];
-	cuboid(p1=array_subindex(span,0), p2=array_subindex(span,1));
+	cuboid(p1=array_subindex(span,0), p2=array_subindex(span,1)) children();
 }
 
 
@@ -257,7 +257,7 @@ module span_cube(xspan, yspan, zspan) {
 //   v = vector to offset along.
 module offsetcube(size=[1,1,1], v=[0,0,0]) {
 	deprecate("offsetcube()", "cuboid()");
-	cuboid(size=size, align=v);
+	cuboid(size=size, align=v) children();
 }
 
 
@@ -379,7 +379,7 @@ module chamfcube(size=[1,1,1], chamfer=0.25, chamfaxes=[1,1,1], chamfcorners=fal
 			(chamfaxes[1]? EDGES_Y_ALL : EDGES_NONE) +
 			(chamfaxes[2]? EDGES_Z_ALL : EDGES_NONE)
 		)
-	);
+	) children();
 }
 
 
@@ -396,7 +396,7 @@ module chamfcube(size=[1,1,1], chamfer=0.25, chamfaxes=[1,1,1], chamfcorners=fal
 //   center = If true, object will be centered.  If false, sits on top of XY plane.
 module rrect(size=[1,1,1], r=0.25, center=false) {
 	deprecate("rrect()", "cuboid()");
-	cuboid(size=size, fillet=r, edges=EDGES_Z_ALL, align=center? V_CENTER : V_UP);
+	cuboid(size=size, fillet=r, edges=EDGES_Z_ALL, align=center? V_CENTER : V_UP) children();
 }
 
 
@@ -413,7 +413,7 @@ module rrect(size=[1,1,1], r=0.25, center=false) {
 //   center = If true, object will be centered.  If false, sits on top of XY plane.
 module rcube(size=[1,1,1], r=0.25, center=false) {
 	deprecate("rcube()", "cuboid()");
-	cuboid(size=size, fillet=r, align=center? V_CENTER : V_UP);
+	cuboid(size=size, fillet=r, align=center? V_CENTER : V_UP) children();
 }
 
 
@@ -459,20 +459,20 @@ module prismoid(
 	orient=ORIENT_Z, align=ALIGN_POS, center=undef
 ) {
 	eps = 0.001;
-	s1 = [max(size1[0], eps), max(size1[1], eps)];
+	shiftby = point3d(point2d(shift));
-	s2 = [max(size2[0], eps), max(size2[1], eps)];
+	s1 = [max(size1.x, eps), max(size1.y, eps)];
-	shiftby = point3d(shift);
+	s2 = [max(size2.x, eps), max(size2.y, eps)];
-	orient_and_align([s1[0], s1[1], h], orient, align, center, noncentered=ALIGN_POS) {
+	orient_and_align([s1.x,s1.y,h], orient, align, center, size2=s2, shift=shift, noncentered=ALIGN_POS, chain=true) {
 		polyhedron(
 			points=[
-				[+s2[0]/2, +s2[1]/2, +h/2] + shiftby,
+				[+s2.x/2, +s2.y/2, +h/2] + shiftby,
-				[+s2[0]/2, -s2[1]/2, +h/2] + shiftby,
+				[+s2.x/2, -s2.y/2, +h/2] + shiftby,
-				[-s2[0]/2, -s2[1]/2, +h/2] + shiftby,
+				[-s2.x/2, -s2.y/2, +h/2] + shiftby,
-				[-s2[0]/2, +s2[1]/2, +h/2] + shiftby,
+				[-s2.x/2, +s2.y/2, +h/2] + shiftby,
-				[+s1[0]/2, +s1[1]/2, -h/2],
+				[+s1.x/2, +s1.y/2, -h/2],
-				[+s1[0]/2, -s1[1]/2, -h/2],
+				[+s1.x/2, -s1.y/2, -h/2],
-				[-s1[0]/2, -s1[1]/2, -h/2],
+				[-s1.x/2, -s1.y/2, -h/2],
-				[-s1[0]/2, +s1[1]/2, -h/2],
+				[-s1.x/2, +s1.y/2, -h/2],
 			],
 			faces=[
 				[0, 1, 2],
@@ -490,6 +490,7 @@ module prismoid(
 			],
 			convexity=2
 		);
+		children();
 	}
 }
 
@@ -513,7 +514,7 @@ module prismoid(
 //   center = If given, overrides `align`.  A true value sets `align=V_CENTER`, false sets `align=V_UP`.
 module trapezoid(size1=[1,1], size2=[1,1], h=1, center=false) {
 	deprecate("trapezoid()", "prismoid()");
-	prismoid(size=size, size2=size2, h=h, center=center);
+	prismoid(size=size, size2=size2, h=h, center=center) children();
 }
 
 
@@ -548,29 +549,31 @@ module rounded_prismoid(
 	align=V_UP, orient=ORIENT_Z, center=undef
 ) {
 	eps = 0.001;
-	maxrad1 = min(size1[0]/2, size1[1]/2);
+	maxrad1 = min(size1.x/2, size1.y/2);
-	maxrad2 = min(size2[0]/2, size2[1]/2);
+	maxrad2 = min(size2.x/2, size2.y/2);
 	rr1 = min(maxrad1, (r1!=undef)? r1 : r);
 	rr2 = min(maxrad2, (r2!=undef)? r2 : r);
 	shiftby = point3d(shift);
-	orient_and_align([size1.x, size1.y, h], orient, align, center, noncentered=ALIGN_POS) {
+	orient_and_align([size1.x, size1.y, h], orient, align, center, size2=size2, shift=shift, noncentered=ALIGN_POS, chain=true) {
-		down(h/2)
+		down(h/2) {
-		hull() {
+			hull() {
-			linear_extrude(height=eps, center=false, convexity=2) {
+				linear_extrude(height=eps, center=false, convexity=2) {
-				offset(r=rr1) {
+					offset(r=rr1) {
-					square([max(eps, size1[0]-2*rr1), max(eps, size1[1]-2*rr1)], center=true);
+						square([max(eps, size1[0]-2*rr1), max(eps, size1[1]-2*rr1)], center=true);
+					}
 				}
-			}
+				up(h-0.01) {
-			up(h-0.01) {
+					translate(shiftby) {
-				translate(shiftby) {
+						linear_extrude(height=eps, center=false, convexity=2) {
-					linear_extrude(height=eps, center=false, convexity=2) {
+							offset(r=rr2) {
-						offset(r=rr2) {
+								square([max(eps, size2[0]-2*rr2), max(eps, size2[1]-2*rr2)], center=true);
-							square([max(eps, size2[0]-2*rr2), max(eps, size2[1]-2*rr2)], center=true);
+							}
 						}
 					}
 				}
 			}
 		}
+		children();
 	}
 }
 
@@ -596,7 +599,7 @@ module pyramid(n=4, h=1, l=1, r=undef, d=undef, circum=false)
 {
 	deprecate("pyramid()", "cyl()");
 	radius = get_radius(r=r, d=d, dflt=l/2/sin(180/n));
-	cyl(r1=radius, r2=0, l=h, circum=circum, $fn=n, realign=true, align=ALIGN_POS);
+	cyl(r1=radius, r2=0, l=h, circum=circum, $fn=n, realign=true, align=ALIGN_POS) children();
 }
 
 
@@ -620,7 +623,7 @@ module prism(n=3, h=1, l=1, r=undef, d=undef, circum=false, center=false)
 {
 	deprecate("prism()", "cyl()");
 	radius = get_radius(r=r, d=d, dflt=l/2/sin(180/n));
-	cyl(r=radius, l=h, circum=circum, $fn=n, realign=true, center=center);
+	cyl(r=radius, l=h, circum=circum, $fn=n, realign=true, center=center) children();
 }
 
 
@@ -644,36 +647,37 @@ module prism(n=3, h=1, l=1, r=undef, d=undef, circum=false, center=false)
 //   right_triangle([60, 10, 40]);
 module right_triangle(size=[1, 1, 1], orient=ORIENT_Y, align=V_ALLPOS, center=undef)
 {
-	siz = scalar_vec3(size);
+	size = scalar_vec3(size);
-	orient_and_align(siz, align=align, center=center) {
+	orient_and_align(size, align=align, center=center, chain=true) {
 		if (orient == ORIENT_X) {
-			ang = atan2(siz[1], siz[2]);
+			ang = atan2(size.y, size.z);
-			masksize = [siz[0], siz[1], norm([siz[1],siz[2]])] + [1,1,1];
+			masksize = [size.x, size.y, norm([size.y,size.z])] + [1,1,1];
 			xrot(ang) {
 				difference() {
-					xrot(-ang) cube(siz, center=true);
+					xrot(-ang) cube(size, center=true);
-					back(masksize[1]/2) cube(masksize, center=true);
+					back(masksize.y/2) cube(masksize, center=true);
 				}
 			}
 		} else if (orient == ORIENT_Y) {
-			ang = atan2(siz[0], siz[2]);
+			ang = atan2(size.x, size.z);
-			masksize = [siz[0], siz[1], norm([siz[0],siz[2]])] + [1,1,1];
+			masksize = [size.x, size.y, norm([size.x,size.z])] + [1,1,1];
 			yrot(-ang) {
 				difference() {
-					yrot(ang) cube(siz, center=true);
+					yrot(ang) cube(size, center=true);
-					right(masksize[0]/2) cube(masksize, center=true);
+					right(masksize.x/2) cube(masksize, center=true);
 				}
 			}
 		} else if (orient == ORIENT_Z) {
-			ang = atan2(siz[0], siz[1]);
+			ang = atan2(size.x, size.y);
-			masksize = [norm([siz[0],siz[1]]), siz[1], siz[2]] + [1,1,1];
+			masksize = [norm([size.x,size.y]), size.y, size.z] + [1,1,1];
 			zrot(-ang) {
 				difference() {
-					zrot(ang) cube(siz, center=true);
+					zrot(ang) cube(size, center=true);
-					back(masksize[1]/2) cube(masksize, center=true);
+					back(masksize.y/2) cube(masksize, center=true);
 				}
 			}
 		}
+		children();
 	}
 }
 
@@ -778,9 +782,12 @@ module cyl(
 	r1 = get_radius(r1, r, d1, d, 1);
 	r2 = get_radius(r2, r, d2, d, 1);
 	l = first_defined([l, h, 1]);
+	size1 = [r1*2,r1*2,l];
+	size2 = [r2*2,r2*2,l];
 	sides = segs(max(r1,r2));
 	sc = circum? 1/cos(180/sides) : 1;
-	orient_and_align([r1*2,r1*2,l], orient, align, center=center) {
+	phi = atan2(l, r1-r2);
+	orient_and_align(size1, orient, align, center=center, size2=size2, chain=true) {
 		zrot(realign? 180/sides : 0) {
 			if (!any_defined([chamfer, chamfer1, chamfer2, fillet, fillet1, fillet2])) {
 				cylinder(h=l, r1=r1*sc, r2=r2*sc, center=true, $fn=sides);
@@ -901,6 +908,7 @@ module cyl(
 				}
 			}
 		}
+		children();
 	}
 }
 
@@ -930,10 +938,8 @@ module cyl(
 //   downcyl(r1=10, r2=20, h=40);
 module downcyl(r=undef, h=undef, l=undef, d=undef, d1=undef, d2=undef, r1=undef, r2=undef)
 {
-	h = first_defined([l, h, 1]);
+	l = first_defined([l, h, 1]);
-	down(h/2) {
+	cyl(r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, l=l, align=V_DOWN) children();
-		cylinder(r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, h=h, center=true);
-	}
 }
 
 
@@ -971,7 +977,7 @@ module downcyl(r=undef, h=undef, l=undef, d=undef, d1=undef, d2=undef, r1=undef,
 //   }
 module xcyl(l=undef, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h=undef, align=V_CENTER, center=undef)
 {
-	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_X, align=align, center=center);
+	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_X, align=align, center=center) children();
 }
 
 
@@ -1009,7 +1015,7 @@ module xcyl(l=undef, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h
 //   }
 module ycyl(l=undef, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h=undef, align=V_CENTER, center=undef)
 {
-	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_Y, align=align, center=center);
+	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_Y, align=align, center=center) children();
 }
 
 
@@ -1047,7 +1053,7 @@ module ycyl(l=undef, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h
 //   }
 module zcyl(l=undef, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, h=undef, align=V_CENTER, center=undef)
 {
-	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_Z, align=align, center=center);
+	cyl(l=l, h=h, r=r, r1=r1, r2=r2, d=d, d1=d1, d2=d2, orient=ORIENT_Z, align=align, center=center) children();
 }
 
 
@@ -1075,7 +1081,7 @@ module chamferred_cylinder(h=1, r=undef, d=undef, chamfer=0.25, chamfedge=undef,
 	deprecate("chamf_cyl()` and `chamferred_cylinder()", "cyl()");
 	r = get_radius(r=r, d=d, dflt=1);
 	chamf = (chamfedge == undef)? chamfer : chamfedge * cos(angle);
-	cyl(l=h, r=r, chamfer1=bottom? chamf : 0, chamfer2=top? chamf : 0, chamfang=angle, center=center);
+	cyl(l=h, r=r, chamfer1=bottom? chamf : 0, chamfer2=top? chamf : 0, chamfang=angle, center=center) children();
 }
 
 
@@ -1099,7 +1105,7 @@ module chamferred_cylinder(h=1, r=undef, d=undef, chamfer=0.25, chamfedge=undef,
 //   bottom = boolean.  If true, chamfer the bottom edges. (Default: True)
 //   center = boolean.  If true, cylinder is centered. (Default: false)
 module chamf_cyl(h=1, r=undef, d=undef, chamfer=0.25, chamfedge=undef, angle=45, center=false, top=true, bottom=true)
-	chamferred_cylinder(h=h, r=r, d=d, chamfer=chamfer, chamfedge=chamfedge, angle=angle, center=center, top=top, bottom=bottom);
+	chamferred_cylinder(h=h, r=r, d=d, chamfer=chamfer, chamfedge=chamfedge, angle=angle, center=center, top=top, bottom=bottom) children();
 
 
 // Module: filleted_cylinder()
@@ -1119,7 +1125,7 @@ module chamf_cyl(h=1, r=undef, d=undef, chamfer=0.25, chamfedge=undef, angle=45,
 //   center = boolean.  If true, cylinder is centered. (Default: false)
 module filleted_cylinder(h=1, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2=undef, fillet=0.25, center=false) {
 	deprecate("filleted_cylinder()", "cyl()");
-	cyl(l=h, r=r, d=d, r1=r1, r2=r2, d1=d1, d2=d2, fillet=fillet, orient=ORIENT_Z, center=center);
+	cyl(l=h, r=r, d=d, r1=r1, r2=r2, d1=d1, d2=d2, fillet=fillet, orient=ORIENT_Z, center=center) children();
 }
 
 
@@ -1142,7 +1148,7 @@ module filleted_cylinder(h=1, r=undef, d=undef, r1=undef, r2=undef, d1=undef, d2
 //   center = boolean.  If true, cylinder is centered. (Default: false)
 module rcylinder(h=1, r=1, r1=undef, r2=undef, d=undef, d1=undef, d2=undef, fillet=0.25, center=false) {
 	deprecate("rcylinder()", "cyl(..., fillet)");
-	cyl(l=h, r=r, d=d, r1=r1, r2=r2, d1=d1, d2=d2, fillet=fillet, orient=ORIENT_Z, center=center);
+	cyl(l=h, r=r, d=d, r1=r1, r2=r2, d1=d1, d2=d2, fillet=fillet, orient=ORIENT_Z, center=center) children();
 }
 
 
@@ -1208,13 +1214,16 @@ module tube(
 	assertion(ir1 <= r1, "Inner radius is larger than outer radius.");
 	assertion(ir2 <= r2, "Inner radius is larger than outer radius.");
 	sides = segs(max(r1,r2));
-	orient_and_align([r1*2,r1*2,h], orient, align, center=center) {
+	size = [r1*2,r1*2,h];
+	size2 = [r2*2,r2*2,h];
+	orient_and_align(size, orient, align, center=center, size2=size2, chain=true) {
 		zrot(realign? 180/sides : 0) {
 			difference() {
-				cylinder(h=h, r1=r1, r2=r2, center=true, $fn=sides);
+				cyl(h=h, r1=r1, r2=r2, $fn=sides) children();
-				cylinder(h=h+0.05, r1=ir1, r2=ir2, center=true);
+				cyl(h=h+0.05, r1=ir1, r2=ir2);
 			}
 		}
+		children();
 	}
 }
 
@@ -1257,10 +1266,12 @@ module torus(
 	irr = get_radius(r=ir, d=id, dflt=0.5);
 	majrad = get_radius(r=r, d=d, dflt=(orr+irr)/2);
 	minrad = get_radius(r=r2, d=d2, dflt=(orr-irr)/2);
-	orient_and_align([(majrad+minrad)*2, (majrad+minrad)*2, minrad*2], orient, align, center=center) {
+	size = [(majrad+minrad)*2, (majrad+minrad)*2, minrad*2];
+	orient_and_align(size, orient, align, center=center, chain=true) {
 		rotate_extrude(convexity=4) {
 			right(majrad) circle(minrad);
 		}
+		children();
 	}
 }
 
@@ -1269,6 +1280,34 @@ module torus(
 // Section: Spheroids
 
 
+// Module: spheroid()
+// Description:
+//   An version of `sphere()` with connector points, orientation, and alignment.
+// Usage:
+//   spheroid(r|d, [circum])
+// Arguments:
+//   r = Radius of the sphere.
+//   d = Diameter of the sphere.
+//   circum = If true, circumscribes the perfect sphere of the given radius/diameter.
+//   orient = Orientation of the sphere, if you don't like where the vertices lay.  Use the `ORIENT_` constants from `constants.scad`.  Default: `ORIENT_Z`.
+//   align = Alignment of the sphere.  Use the `V_` constants from `constants.scad`.  Default: `V_CENTER`.
+// Example:
+//   spheroid(d=100, circum=true, $fn=10);
+module spheroid(r=undef, d=undef, circum=false, orient=V_UP, align=V_CENTER)
+{
+	r = get_radius(r=r, d=d, dflt=1);
+	hsides = segs(r);
+	vsides = ceil(hsides/2);
+	rr = circum? (r / cos(90/vsides) / cos(180/hsides)) : r;
+	size = [2*rr, 2*rr, 2*rr];
+	orient_and_align(size, orient, align, chain=true) {
+		sphere(r=rr);
+		children();
+	}
+}
+
+
+
 // Module: staggered_sphere()
 //
 // Description:
@@ -1281,16 +1320,18 @@ module torus(
 //   r = Radius of the sphere.
 //   d = Diameter of the sphere.
 //   circum = If true, circumscribes the perfect sphere of the given size.
+//   orient = Orientation of the sphere, if you don't like where the vertices lay.  Use the `ORIENT_` constants from `constants.scad`.  Default: `ORIENT_Z`.
+//   align = Alignment of the sphere.  Use the `V_` constants from `constants.scad`.  Default: `V_CENTER`.
 //
 // Example:
 //   staggered_sphere(d=100, circum=true, $fn=10);
-module staggered_sphere(r=undef, d=undef, circum=false, align=V_CENTER) {
+module staggered_sphere(r=undef, d=undef, circum=false, orient=V_UP, align=V_CENTER) {
 	r = get_radius(r=r, d=d, dflt=1);
 	sides = segs(r);
 	vsides = max(3, ceil(sides/2))+1;
 	step = 360/sides;
 	vstep = 180/(vsides-1);
-	rr = circum? r/cos(180/sides)/cos(180/sides) : r;
+	rr = circum? (r / cos(180/sides) / cos(90/vsides)) : r;
 	pts = concat(
 		[[0,0,rr]],
 		[
@@ -1320,7 +1361,11 @@ module staggered_sphere(r=undef, d=undef, circum=false, align=V_CENTER) {
 			) each [[v1,v4,v3], [v1,v2,v4]]
 		]
 	);
-	polyhedron(points=pts, faces=faces);
+	size = [2*rr, 2*rr, 2*rr];
+	orient_and_align(size, orient, align, chain=true) {
+		polyhedron(points=pts, faces=faces);
+		children();
+	}
 }
 
 
@@ -1394,10 +1439,12 @@ module teardrop(r=undef, d=undef, l=undef, h=undef, ang=45, cap_h=undef, orient=
 {
 	r = get_radius(r=r, d=d, dflt=1);
 	l = first_defined([l, h, 1]);
-	orient_and_align([r*2,r*2,l], orient, align) {
+	size = [r*2,r*2,l];
+	orient_and_align(size, orient, align, chain=true) {
 		linear_extrude(height=l, center=true, slices=2) {
 			teardrop2d(r=r, ang=ang, cap_h=cap_h);
 		}
+		children();
 	}
 }
 
@@ -1429,13 +1476,15 @@ module onion(cap_h=undef, r=undef, d=undef, maxang=45, h=undef, orient=ORIENT_Z,
 	r = get_radius(r=r, d=d, dflt=1);
 	h = first_defined([cap_h, h]);
 	maxd = 3*r/tan(maxang);
-	orient_and_align([r*2,r*2,r*2], orient, align) {
+	size = [r*2,r*2,r*2];
+	orient_and_align(size, orient, align, chain=true) {
 		rotate_extrude(convexity=2) {
 			difference() {
 				teardrop2d(r=r, ang=maxang, cap_h=h);
 				left(r) square(size=[2*r,maxd], center=true);
 			}
 		}
+		children();
 	}
 }
 
@@ -1464,7 +1513,8 @@ module onion(cap_h=undef, r=undef, d=undef, maxang=45, h=undef, orient=ORIENT_Z,
 module narrowing_strut(w=10, l=100, wall=5, ang=30, orient=ORIENT_Y, align=V_UP)
 {
 	h = wall + w/2/tan(ang);
-	orient_and_align([w, h, l], orient, align, orig_orient=ORIENT_Z) {
+	size = [w, h, l];
+	orient_and_align(size, orient, align, chain=true) {
 		fwd(h/2) {
 			linear_extrude(height=l, center=true, slices=2) {
 				back(wall/2) square([w, wall], center=true);
@@ -1478,6 +1528,7 @@ module narrowing_strut(w=10, l=100, wall=5, ang=30, orient=ORIENT_Y, align=V_UP)
 				}
 			}
 		}
+		children();
 	}
 }
 
@@ -1505,7 +1556,7 @@ module narrowing_strut(w=10, l=100, wall=5, ang=30, orient=ORIENT_Y, align=V_UP)
 //   thinning_wall(h=50, l=80, thick=4);
 // Example: Trapezoidal
 //   thinning_wall(h=50, l=[80,50], thick=4);
-module thinning_wall(h=50, l=100, thick=5, ang=30, strut=5, wall=2, orient=ORIENT_X, align=V_CENTER)
+module thinning_wall(h=50, l=100, thick=5, ang=30, strut=5, wall=2, orient=ORIENT_Z, align=V_CENTER)
 {
 	l1 = (l[0] == undef)? l : l[0];
 	l2 = (l[1] == undef)? l : l[1];
@@ -1528,7 +1579,8 @@ module thinning_wall(h=50, l=100, thick=5, ang=30, strut=5, wall=2, orient=ORIEN
 	y1 = thick/2;
 	y2 = y1 - min(z2-z3, x2-x3) * sin(ang);
 
-	orient_and_align([l1, thick, h], orient, align, orig_orient=ORIENT_X) {
+	size = [l1, thick, h];
+	orient_and_align(size, orient, align, size2=[l2,thick], chain=true) {
 		polyhedron(
 			points=[
 				[-x4, -y1, -z1],
@@ -1620,6 +1672,7 @@ module thinning_wall(h=50, l=100, thick=5, ang=30, strut=5, wall=2, orient=ORIEN
 			],
 			convexity=6
 		);
+		children();
 	}
 }
 
@@ -1649,23 +1702,27 @@ module braced_thinning_wall(h=50, l=100, thick=5, ang=30, strut=5, wall=2, orien
 {
 	dang = atan((h-2*strut)/(l-2*strut));
 	dlen = (h-2*strut)/sin(dang);
-	orient_and_align([thick, l, h], orient, align, orig_orient=ORIENT_Y) {
+	size = [l, thick, h];
-		xrot_copies([0, 180]) {
+	orient_and_align(size, orient, align, orig_orient=ORIENT_Y, chain=true) {
-			down(h/2) narrowing_strut(w=thick, l=l, wall=strut, ang=ang);
+		union() {
-			fwd(l/2) xrot(-90) narrowing_strut(w=thick, l=h-0.1, wall=strut, ang=ang);
+			xrot_copies([0, 180]) {
-			intersection() {
+				down(h/2) narrowing_strut(w=thick, l=l, wall=strut, ang=ang);
-				cube(size=[thick, l, h], center=true);
+				fwd(l/2) xrot(-90) narrowing_strut(w=thick, l=h-0.1, wall=strut, ang=ang);
-				xrot_copies([-dang,dang]) {
+				intersection() {
-					zspread(strut/2) {
+					cube(size=[thick, l, h], center=true);
-						scale([1,1,1.5]) yrot(45) {
+					xrot_copies([-dang,dang]) {
-							cube(size=[thick/sqrt(2), dlen, thick/sqrt(2)], center=true);
+						zspread(strut/2) {
+							scale([1,1,1.5]) yrot(45) {
+								cube(size=[thick/sqrt(2), dlen, thick/sqrt(2)], center=true);
+							}
 						}
+						cube(size=[thick, dlen, strut/2], center=true);
 					}
-					cube(size=[thick, dlen, strut/2], center=true);
 				}
 			}
+			cube(size=[wall, l-0.1, h-0.1], center=true);
 		}
-		cube(size=[wall, l-0.1, h-0.1], center=true);
+		children();
 	}
 }
 
@@ -1702,7 +1759,8 @@ module thinning_triangle(h=50, l=100, thick=5, ang=30, strut=5, wall=3, diagonly
 {
 	dang = atan(h/l);
 	dlen = h/sin(dang);
-	orient_and_align([thick, l, h], orient, align, center=center, noncentered=V_UP+V_BACK, orig_orient=ORIENT_Y) {
+	size = [thick, l, h];
+	orient_and_align(size, orient, align, center=center, noncentered=V_UP+V_BACK, orig_orient=ORIENT_Y, chain=true) {
 		difference() {
 			union() {
 				if (!diagonly) {
@@ -1725,6 +1783,7 @@ module thinning_triangle(h=50, l=100, thick=5, ang=30, strut=5, wall=3, diagonly
 				}
 			}
 		}
+		children();
 	}
 }
 
@@ -1750,7 +1809,7 @@ module thinning_triangle(h=50, l=100, thick=5, ang=30, strut=5, wall=3, diagonly
 module thinning_brace(h=50, l=100, thick=5, ang=30, strut=5, wall=3, center=true)
 {
 	deprecate("thinning_brace()", "thinning_triangle(..., diagonly=true)");
-	thinning_triangle(h=h, l=l, thick=thick, ang=ang, strut=strut, wall=wall, diagonly=true, center=center);
+	thinning_triangle(h=h, l=l, thick=thick, ang=ang, strut=strut, wall=wall, diagonly=true, center=center) children();
 }
 
 
@@ -1801,17 +1860,21 @@ module sparse_strut(h=50, l=100, thick=4, maxang=30, strut=5, max_bridge=20, ori
 	ang = atan(ystep/zstep);
 	len = zstep / cos(ang);
 
-	orient_and_align([thick, l, h], orient, align, orig_orient=ORIENT_Y) {
+	size = [thick, l, h];
-		zspread(zoff*2)
+	orient_and_align(size, orient, align, orig_orient=ORIENT_Y, chain=true) {
-			cube(size=[thick, l, strut], center=true);
+		union() {
-		yspread(yoff*2)
+			zspread(zoff*2)
-			cube(size=[thick, strut, h], center=true);
+				cube(size=[thick, l, strut], center=true);
-		yspread(ystep, n=yreps) {
+			yspread(yoff*2)
-			zspread(zstep, n=zreps) {
+				cube(size=[thick, strut, h], center=true);
-				xrot( ang) cube(size=[thick, strut, len], center=true);
+			yspread(ystep, n=yreps) {
-				xrot(-ang) cube(size=[thick, strut, len], center=true);
+				zspread(zstep, n=zreps) {
+					xrot( ang) cube(size=[thick, strut, len], center=true);
+					xrot(-ang) cube(size=[thick, strut, len], center=true);
+				}
 			}
 		}
+		children();
 	}
 }
 
@@ -1866,7 +1929,8 @@ module sparse_strut3d(h=50, l=100, w=50, thick=3, maxang=40, strut=3, max_bridge
 	supp_reps = floor(cross_len/2/(zstep*sin(supp_ang)));
 	supp_step = cross_len/2/supp_reps;
 
-	orient_and_align([w, l, h], orient, align, orig_orient=ORIENT_Y) {
+	size = [w, l, h];
+	orient_and_align(size, orient, align, orig_orient=ORIENT_Y, chain=true) {
 		intersection() {
 			union() {
 				ybridge = (l - (yreps+1) * strut) / yreps;
@@ -1908,6 +1972,7 @@ module sparse_strut3d(h=50, l=100, w=50, thick=3, maxang=40, strut=3, max_bridge
 			}
 			cube([w,l,h], center=true);
 		}
+		children();
 	}
 }
 
@@ -1943,20 +2008,23 @@ module corrugated_wall(h=50, l=100, thick=5, strut=5, wall=2, orient=ORIENT_Y, a
 	steps = quantup(segs(thick/2),4);
 	step = period/steps;
 	il = l - 2*strut + 2*step;
-	orient_and_align([thick, l, h], orient, align, orig_orient=ORIENT_Y) {
+	size = [thick, l, h];
-		linear_extrude(height=h-2*strut+0.1, slices=2, convexity=ceil(2*il/period), center=true) {
+	orient_and_align(size, orient, align, orig_orient=ORIENT_Y, chain=true) {
-			polygon(
+		union() {
-				points=concat(
+			linear_extrude(height=h-2*strut+0.1, slices=2, convexity=ceil(2*il/period), center=true) {
-					[for (y=[-il/2:step:il/2]) [amplitude*sin(y/period*360)-wall/2, y] ],
+				polygon(
-					[for (y=[il/2:-step:-il/2]) [amplitude*sin(y/period*360)+wall/2, y] ]
+					points=concat(
-				)
+						[for (y=[-il/2:step:il/2]) [amplitude*sin(y/period*360)-wall/2, y] ],
-			);
+						[for (y=[il/2:-step:-il/2]) [amplitude*sin(y/period*360)+wall/2, y] ]
-		}
+					)
-
+				);
-		difference() {
+			}
-			cube([thick, l, h], center=true);
+			difference() {
-			cube([thick+0.5, l-2*strut, h-2*strut], center=true);
+				cube([thick, l, h], center=true);
+				cube([thick+0.5, l-2*strut, h-2*strut], center=true);
+			}
 		}
+		children();
 	}
 }
 
@@ -2016,7 +2084,8 @@ module pie_slice(
 	r1 = get_radius(r1, r, d1, d, 10);
 	r2 = get_radius(r2, r, d2, d, 10);
 	maxd = max(r1,r2)+0.1;
-	orient_and_align([2*r1, 2*r1, l], orient, align, center=center) {
+	size = [2*r1, 2*r1, l];
+	orient_and_align(size, orient, align, center=center, chain=true) {
 		difference() {
 			cylinder(r1=r1, r2=r2, h=l, center=true);
 			if (ang<180) rotate(ang) back(maxd/2) cube([2*maxd, maxd, l+0.1], center=true);
@@ -2025,6 +2094,7 @@ module pie_slice(
 				if (ang>180) rotate(ang-180) back(maxd/2) cube([2*maxd, maxd, l+0.1], center=true);
 			}
 		}
+		children();
 	}
 }
 
@@ -2057,7 +2127,8 @@ module pie_slice(
 //   interior_fillet(l=40, r=10, orient=ORIENT_Y_90);
 module interior_fillet(l=1.0, r=1.0, ang=90, overlap=0.01, orient=ORIENT_X, align=V_CENTER) {
 	dy = r/tan(ang/2);
-	orient_and_align([l,r,r], orient, align, orig_orient=ORIENT_X) {
+	size = [l,r,r];
+	orient_and_align(size, orient, align, orig_orient=ORIENT_X, chain=true) {
 		difference() {
 			translate([0,-overlap/tan(ang/2),-overlap]) {
 				if (ang == 90) {
@@ -2068,6 +2139,7 @@ module interior_fillet(l=1.0, r=1.0, ang=90, overlap=0.01, orient=ORIENT_X, alig
 			}
 			translate([0,dy,r]) xcyl(l=l+0.1, r=r);
 		}
+		children();
 	}
 }
 
@@ -2108,6 +2180,8 @@ module slot(
 	r1 = get_radius(r1=r1, r=r, d1=d1, d=d, dflt=5);
 	r2 = get_radius(r1=r2, r=r, d1=d2, d=d, dflt=5);
 	sides = quantup(segs(max(r1, r2)), 4);
+	// TODO: implement orient and align.
+	// TODO: implement connectors.
 	hull() spread(p1=p1, p2=p2, l=l, n=2) cyl(l=h, r1=r1, r2=r2, center=true, $fn=sides);
 }
 
@@ -2156,7 +2230,8 @@ module arced_slot(
 	sr2 = get_radius(sr2, sr, sd2, sd, 2);
 	fn_minor = first_defined([$fn2, $fn]);
 	da = ea - sa;
-	orient_and_align([r+sr1, r+sr1, h], orient, align) {
+	size = [r+sr1, r+sr1, h];
+	orient_and_align(size, orient, align, chain=true) {
 		translate(cp) {
 			zrot(sa) {
 				difference() {
@@ -2167,6 +2242,7 @@ module arced_slot(
 				zrot(da) right(r) cylinder(h=h, r1=sr1, r2=sr2, center=true, $fn=fn_minor);
 			}
 		}
+		children();
 	}
 }
 

transforms.scad

@@ -1439,27 +1439,22 @@ module zrot_copies(rots=[], cp=[0,0,0], n=undef, count=undef, sa=0, offset=0, r=
 
 
 // Module: xring()
-// 
 // Description:
 //   Distributes `n` copies of the given children on a circle of radius `r`
 //   around the X axis.  If `rot` is true, each copy is rotated in place to keep
 //   the same side towards the center.  The first, unrotated copy will be at the
 //   starting angle `sa`.
-//
 // Usage:
 //   xring(n, r, [sa], [cp], [rot]) ...
-//
 // Arguments:
 //   n = Number of copies of children to distribute around the circle. (Default: 2)
 //   r = Radius of ring to distribute children around. (Default: 0)
 //   sa = Start angle for first (unrotated) copy.  (Default: 0)
 //   cp = Centerpoint of ring.  Default: [0,0,0]
 //   rot = If true, rotate each copy to keep the same side towards the center of the ring.  Default: true.
-//
 // Side Effects:
 //   `$ang` is set to the rotation angle of each child copy, and can be used to modify each child individually.
 //   `$idx` is set to the index value of each child copy.
-//
 // Examples:
 //   xring(n=6, r=10) xrot(-90) cylinder(h=20, r1=5, r2=0);
 //   xring(n=6, r=10, sa=45) xrot(-90) cylinder(h=20, r1=5, r2=0);
@@ -1643,7 +1638,7 @@ module ovoid_spread(r=undef, d=undef, n=100, cone_ang=90, scale=[1,1,1], perp=tr
 	theta_phis = [for (x=[0:n-1]) [180*(1+sqrt(5))*(x+0.5)%360, acos(1-2*(x+0.5)/cnt)]];
 
 	for ($idx = [0:len(theta_phis)-1]) {
-	    tp = theta_phis[$idx];
+		tp = theta_phis[$idx];
 		xyz = spherical_to_xyz(r, tp[0], tp[1]);
 		$pos = vmul(xyz,scale);
 		$theta = tp[0];
@@ -2274,17 +2269,28 @@ module shell2d(thickness, or=0, ir=0, fill=0, round=0)
 //   Named alignments, as well as `ALIGN_NEG`/`ALIGN_POS` are aligned pre-rotation.
 //
 // Usage:
-//   orient_and_align(size, [orient], [align], [center], [noncentered], [orig_orient], [orig_align], [alignments]) ...
+//   orient_and_align(size, [orient], [align], [center], [noncentered], [orig_orient], [orig_align], [alignments], [chain]) ...
 //
 // Arguments:
-//   size = The size of the part.
+//   size = The [X,Y,Z] size of the part.
-//   orient = The axis to align to.  Use ORIENT_ constants from constants.scad
+//   size2 = The [X,Y] size of the top of the part.
+//   shift = The [X,Y] offset of the top of the part, compared to the bottom of the part.
+//   orient = The axis to align to.  Use `ORIENT_` constants from `constants.scad`.
 //   align = The side of the origin the part should be aligned with.
 //   center = If given, overrides `align`.  If true, centers vertically.  If false, `align` will be set to the value in `noncentered`.
 //   noncentered = The value to set `align` to if `center` == `false`.  Default: `V_UP`.
 //   orig_orient = The original orientation of the part.  Default: `ORIENT_Z`.
 //   orig_align = The original alignment of the part.  Default: `V_CENTER`.
-//   alignments = A list of `["name", [X,Y,Z]]` alignment-label/offset pairs.
+//   alignments = A list of extra, non-standard connectors that can be aligned to.
+//   chain = If true, allow attachable children.
+//
+// Side Effects:
+//   `$parent_size` is set to the parent object's cubical region size.
+//   `$parent_size2` is set to the parent object's top [X,Y] size.
+//   `$parent_shift` is set to the parent object's `shift` value, if any.
+//   `$parent_orient` is set to the parent object's `orient` value.
+//   `$parent_align` is set to the parent object's `align` value.
+//   `$parent_conns` is set to the parent object's list of non-standard extra connectors.
 //
 // Example:
 //   #cylinder(d=5, h=10);
@@ -2293,55 +2299,321 @@ module orient_and_align(
 	size=undef, orient=ORIENT_Z, align=V_CENTER,
 	center=undef, noncentered=ALIGN_POS,
 	orig_orient=ORIENT_Z, orig_align=V_CENTER,
-	alignments=[]
+	size2=undef, shift=[0,0],
+	alignments=[], chain=false
 ) {
-	algn = is_def(center)? (center? V_CENTER : noncentered) : align;
+	size2 = point2d(default(size2, size));
-    if (orig_align != V_CENTER) {
+	shift = point2d(shift);
-		orient_and_align(size=size, orient=orient, align=algn) {
+	align = is_def(center)? (center? V_CENTER : noncentered) : align;
-			translate(vmul(size/2, -orig_align)) children();
+	m = matrix4_mult(concat(
-		}
+		(orig_align==V_CENTER)? [] : [
-    } else if (orig_orient != ORIENT_Z) {
+			// If original alignment is not centered, center it.
-		rotsize = (
+			matrix4_translate(vmul(size/2, -orig_align))
-			(orig_orient==ORIENT_X)? [size[1], size[2], size[0]] :
+		],
-			(orig_orient==ORIENT_Y)? [size[0], size[2], size[1]] :
+		(orig_orient==ORIENT_Z)? [] : [
-			vabs(rotate_points3d([size], orig_orient, reverse=true)[0])
+			// If original orientation is not upright, rotate it upright.
-		);
+			matrix4_zrot(-orig_orient.z),
-		orient_and_align(size=rotsize, orient=orient, align=algn) {
+			matrix4_yrot(-orig_orient.y),
-			rot(orig_orient,reverse=true) children();
+			matrix4_xrot(-orig_orient.x)
-		}
+		],
-	} else if (is_scalar(algn)) {
+		($attach_to!=undef)? (
-		// If align is a number and not a vector, then translate PRE-rotation.
+			let(
-		orient_and_align(size=size, orient=orient) {
+				conn = find_connector($attach_to, size.z, size, size2=size2, shift=shift),
-			translate(vmul(size/2, algn*V_UP)) children();
+				ang = vector_angle(conn[2],V_DOWN),
-		}
+				axis = vector_axis(conn[2],V_DOWN),
-	} else if (is_str(algn)) {
+				ang2 = (conn[2]==V_UP || conn[2]==V_DOWN)? 0 : 180-conn[3],
-		// If align is a string, look for an alignments label that matches.
+				axis2 = rotate_points3d([axis],[0,0,ang2])[0]
-		found = search([algn], alignments, num_returns_per_match=1);
+			) [
-		if (found != [[]]) {
+				matrix4_translate(-conn[1]),
-			orient_and_align(size=size, orient=orient) {
+				matrix4_zrot(ang2),
-				idx = found[0];
+				matrix4_rot_by_axis(axis2, ang)
-				delta = alignments[idx][1];
+			]
-				translate(-delta) children();
+		) : concat(
-			}
+			(!is_scalar(align) && !is_str(align))? [] : [
+				let(conn = find_connector(align, size.z, size, size2=size2, shift=shift, extra_conns=alignments))
+				matrix4_translate(-conn[1])
+			],
+			(orient==ORIENT_Z)? [] : [
+				matrix4_xrot(orient.x),
+				matrix4_yrot(orient.y),
+				matrix4_zrot(orient.z)
+			],
+			(!is_array(align) || align==[0,0,0])? [] : [
+				let(conn = find_connector(align, size.z, size, size2=size2, shift=shift))
+				matrix4_translate(conn[1])
+			]
+		)
+	));
+	$attach_to = undef;
+	$parent_size   = size;
+	$parent_size2  = size2;
+	$parent_shift  = shift;
+	$parent_orient = orient;
+	$parent_align  = align;
+	$parent_conns  = alignments;
+	tags = _str_char_split($tags, " ");
+	s_tags = $tags_shown;
+	h_tags = $tags_hidden;
+	shown  = !s_tags || any([for (tag=tags) in_list(tag, s_tags)]);
+	hidden = any([for (tag=tags) in_list(tag, h_tags)]);
+	echo(tags=tags, shown=shown, hidden=hidden, view=shown&&!hidden);
+	multmatrix(m) {
+		if ($children>1 && chain) {
+			if(shown && !hidden) color($color) for (i=[0:$children-2]) children(i);
+			children($children-1);
 		} else {
-			assertion(1==0, str("Alignment label '", algn, "' is not known.", (alignments? str("  Try one of ", [for (v=alignments) v[0]], ".") : "")));
+			if(shown && !hidden) color($color) children();
 		}
-	} else if (orient != ORIENT_Z) {
-		rotsize = (
-			(orient==ORIENT_X)? [size[2], size[0], size[1]] :
-			(orient==ORIENT_Y)? [size[0], size[2], size[1]] :
-			vabs(rotate_points3d([size], orient)[0])
-		);
-		orient_and_align(size=rotsize, align=algn) {
-			rotate(orient) children();
-		}
-	} else if (is_def(algn) && algn != [0,0,0]) {
-		translate(vmul(size/2, algn)) children();
-	} else {
-		children();
 	}
 }
 
 
 
+// Internal.  Not exposed.
+function _str_char_split(s,delim,n=0,acc=[],word="") =
+	(n>=len(s))? concat(acc, [word]) :
+	(s[n]==delim)?
+		_str_char_split(s,delim,n+1,concat(acc,[word]),"") :
+		_str_char_split(s,delim,n+1,acc,str(word,s[n]));
+
+
+
+// Function: connector()
+// Usage:
+//   connector(name, pos, dir, [rot])
+// Description:
+//   Creates a connector data structure.
+// Arguments:
+//   name = The string name of the connector.  Lowercase.  Words separated by single dashes.  No spaces.
+//   pos = The [X,Y,Z] position of the connector.
+//   dir = A vector pointing in the direction parts should project from the connector position.
+//   rot = If needed, the angle to rotate the part around the direction vector.
+function connector(name, pos=[0,0,0], dir=V_UP, rot=0) = [name, pos, dir, rot];
+
+
+
+// Function: find_connector()
+// Usage:
+//   find_connector(align, h, size, [size2], [shift], [edges], [corners]);
+// Description:
+//   Generates a list of typical connectors for a cubical region of the given size.
+// Arguments:
+//   align = Named alignment/connector string.
+//   h = Height of the region.
+//   size = The [X,Y] size of the bottom of the cubical region.
+//   size2 = The [X,Y] size of the top of the cubical region.
+//   shift = The [X,Y] amount to shift the center of the top with respect to the center of the bottom.
+//   extra_conns = A list of extra named connectors.
+function find_connector(align, h, size, size2=undef, shift=[0,0], extra_conns=[]) =
+	let(
+		eps = 1e-9,
+		shift = point3d(shift),
+		size = point3d(point2d(size)),
+		size2 = (size2!=undef)? point3d(point2d(size2)) : size,
+		found = !is_str(align)? [] : search([align], extra_conns, num_returns_per_match=1)[0]
+	) (found!=[])? extra_conns[found] : let(
+		words = is_scalar(align)? (
+			align==ALIGN_NEG? ["top"] :
+			align==ALIGN_POS? ["bottom"] :
+			["center"]
+		) : is_array(align)? align : _str_char_split(align,"-"),
+		ovec = is_array(align)? align :
+			sum([
+				for (word = words) 
+					word=="left"? V_LEFT :
+					word=="right"? V_RIGHT :
+					word=="front"? V_FWD :
+					word=="back"? V_BACK :
+					word=="top"? V_UP :
+					word=="bottom"? V_DOWN :
+					word=="center"? V_ZERO :
+					assertion(false,
+						str(
+							"Alignment label '", align, "' is not known.",
+							(!extra_conns? "" : str(
+								"  Try one of ", [for (v=extra_conns) v[0]], " or the standard alignments."
+							))
+						)
+					)
+			]),
+		top = [-size2/2+shift, shift, size2/2+shift],
+		bot = [-size/2, V_ZERO, size/2],
+		toppt = [top[ovec.x+1].x, top[ovec.y+1].y,  h/2],
+		botpt = [bot[ovec.x+1].x, bot[ovec.y+1].y, -h/2],
+		pos = lerp(botpt, toppt, (ovec.z+1)/2),
+		oang = (
+			ovec == V_UP? 0 :
+			ovec == V_DOWN? 0 :
+			(norm([ovec.x,ovec.y]) < eps)? 0 : atan2(ovec.y, ovec.x)+90
+		),
+		vec = (
+			abs(ovec.z) > eps? ovec :
+			rotate_points3d([ovec], from=V_UP, to=toppt-botpt)[0]
+		)
+	) [align, pos, vec, oang];
+
+
+
+// Module: attach()
+// Usage:
+//   attach(name, [overlap], [norot]) ...
+//   attach(name, to, [overlap]) ...
+// Description:
+//   Attaches children to a parent object at an attachment point and orientation.
+// Arguments:
+//   name = The name of the parent attachment point to attach to.
+//   to = The name of the child attachment point.
+//   overlap = Amount to sink child into the parent.
+//   norot = If true, don't rotate children when aligning to the attachment point.
+// Example:
+//   spheroid(d=20) {
+//       attach("top")   down(1.5) cyl(l=11.5, d1=10, d2=5, align="bottom");
+//       attach("right", "bottom") down(1.5) cyl(l=11.5, d1=10, d2=5);
+//       attach("front") down(1.5) cyl(l=11.5, d1=10, d2=5, align="bottom");
+//   }
+module attach(name, to=undef, overlap=undef, norot=false)
+{
+	assertion($parent_size != undef, "No object to attach to!");
+	overlap = (overlap!=undef)? overlap : $overlap;
+	conn = find_connector(name, $parent_size.z, point2d($parent_size), size2=$parent_size2, shift=$parent_shift, extra_conns=$parent_conns);
+	pos = conn[1];
+	vec = conn[2];
+	ang = conn[3];
+	$attach_to = to;
+	$attach_conn = conn;
+	if (norot || (norm(vec-V_UP)<1e-9 && ang==0)) {
+		translate(pos) translate([0,0,-overlap]) children();
+	} else {
+		translate(pos) rot(ang,from=V_UP,to=vec) translate([0,0,-overlap]) children();
+	}
+}
+
+
+// Module: tags()
+// Usage:
+//   tags(tags) ...
+// Description:
+//   Marks all children with the given tags.
+// Arguments:
+//   tags = String containing space delimited set of tags to apply.
+module tags(tags)
+{
+	$tags = tags;
+	children();
+}
+
+
+// Module: recolor()
+// Usage:
+//   recolor(c) ...
+// Description:
+//   Sets the color for children that can use the $color special variable.
+// Example:
+//   recolor("red") cyl(l=20, d=10);
+module recolor(c)
+{
+	$color = c;
+	children();
+}
+
+
+// Module: hide()
+// Usage:
+//   hide(tags) ...
+// Description: Hides all children with the given tags.
+module hide(tags="")
+{
+	$tags_hidden = tags==""? [] : _str_char_split(tags, " ");
+	children();
+}
+
+
+// Module: show()
+// Usage:
+//   show(tags) ...
+// Description: Shows only children with the given tags.
+module show(tags="")
+{
+	$tags_shown = tags==""? [] : _str_char_split(tags, " ");
+	children();
+}
+
+
+// Module: diff()
+// Usage:
+//   diff(neg, [keep]) ...
+//   diff(neg, pos, [keep]) ...
+// Description:
+//   If `neg` is given, takes the union of all children with tags
+//   that are in `neg`, and differences them from the union of all
+//   children with tags in `pos`.  If `pos` is not given, then all
+//   items in `neg` are differenced from all items not in `neg`.  If
+//   `keep` is given, all children with tags in `keep` are then unioned
+//   with the result.  If `keep` is not given, all children without
+//   tags in `pos` or `neg` are then unioned with the result.
+// Arguments:
+//   neg = String containing space delimited set of tag names of children to difference away.
+//   pos = String containing space delimited set of tag names of children to be differenced away from.
+//   keep = String containing space delimited set of tag names of children to keep whole.
+module diff(neg, pos=undef, keep=undef)
+{
+	difference() {
+		if (pos != undef) {
+			show(pos) children();
+		} else {
+			if (keep == undef) {
+				hide(neg) children();
+			} else {
+				hide(str(neg," ",keep)) children();
+			}
+		}
+		show(neg) children();
+	}
+	if (keep!=undef) {
+		show(keep) children();
+	} else if (pos!=undef) {
+		hide(str(pos," ",neg)) children();
+	}
+}
+
+
+// Module: intersect()
+// Usage:
+//   intersect(a, [keep]) ...
+//   intersect(a, b, [keep]) ...
+// Description:
+//   If `a` is given, takes the union of all children with tags that
+//   are in `a`, and intersection()s them with the union of all
+//   children with tags in `b`.  If `b` is not given, then the union
+//   of all items with tags in `a` are intersection()ed with the union
+//   of all items without tags in `a`.  If `keep` is given, then the
+//   result is unioned with all the children with tags in `keep`.  If
+//   `keep` is not given, all children without tags in `a` or `b` are
+//   unioned with the result.
+// Arguments:
+//   a = String containing space delimited set of tag names of children.
+//   b = String containing space delimited set of tag names of children.
+//   keep = String containing space delimited set of tag names of children to keep whole.
+module intersect(a, b=undef, keep=undef)
+{
+	intersection() {
+		if (b != undef) {
+			show(b) children();
+		} else {
+			if (keep == undef) {
+				hide(a) children();
+			} else {
+				hide(str(a," ",keep)) children();
+			}
+		}
+		show(a) children();
+	}
+	if (keep!=undef) {
+		show(keep) children();
+	} else if (b!=undef) {
+		hide(str(a," ",b)) children();
+	}
+}
+
+
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