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attachments fixes/tweaks
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@adrianVmariano
adrianVmariano committed Sep 28, 2024
1 parent 7da26d3 commit 55aafee
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81 changes: 71 additions & 10 deletions attachments.scad
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Original file line number Diff line number Diff line change
Expand Up @@ -778,7 +778,12 @@ function _make_anchor_legal(anchor,geom) =
// Note that spin is not permitted for
// 2D objects because it would change the child orientation so that the anchors are no longer parallel.
// When you use `align=` you can also adjust the position using `inset=`, which shifts the child
// away from the edge or corner it is aligned to.
// away from the edge or corner it is aligned to.
// .
// Note that the concept of alignment doesn't always make sense for objects without corners, such as spheres or cylinders.
// In same cases the alignments using such children will be odd because the alignment computation is trying to
// place a non-existent corner somewhere. Because attach() doesn't have in formation about the child when
// it runs it cannot handle curved shapes differently from cubes, so this behavior cannot be changed.
// .
// If you give `inside=true` then the anchor arrows are lined up so they are pointing the same direction and
// the child object will be located inside the parent. In this case a default "remove" tag is applied to
Expand Down Expand Up @@ -881,6 +886,29 @@ function _make_anchor_legal(anchor,geom) =
// attach(RIGHT+FRONT, TOP, inside=true) cuboid([10,3,5]);
// attach(RIGHT+FRONT, TOP, inside=true, align=TOP,shiftout=.01) cuboid([5,1,2]);
// }
// Example: Attaching a 3d edge mask. Simple 2d masks can be done using {{edge_profile()}} but this mask varies along its length.
// module wavy_edge(length,cycles, r, steps, n)
// {
// rmin = is_vector(r) ? r[0] : 0.01;
// rmax = is_vector(r) ? r[1] : r;
// layers = [for(z=[0:steps])
// let(
// r=rmin+(rmax-rmin)/2*(cos(z*360*cycles/steps)+1),ff=echo(r=r)
// )
// path3d( concat([[0,0]],
// arc(corner=path2d([BACK,CTR,RIGHT]), n=n, r=r)),
// z/steps*length-length/2)
// ];
// attachable([rmax,rmax,length]){
// skin(layers,slices=0);
// children();
// }
// }
// diff()
// cuboid(25)
// attach([TOP+RIGHT,TOP+LEFT,TOP+FWD, FWD+RIGHT], FWD+LEFT, inside=true, shiftout=.01)
// wavy_edge(length=25.1,cycles=1.4,r=4,steps=24,n=15);


module attach(parent, child, overlap, align, spin=0, norot, inset=0, shiftout=0, inside=false, from, to)
{
Expand All @@ -905,10 +933,11 @@ module attach(parent, child, overlap, align, spin=0, norot, inset=0, shiftout=0,
assert(is_undef(align) || !is_string(child), "child is a named anchor. Named anchors are not supported with align=");

two_d = _attach_geom_2d($parent_geom);
basegeom = $parent_geom[0]=="conoid" ? attach_geom(r=2,h=2)
: $parent_geom[0]=="spheroid" ? echo("here")attach_geom(r=2)
basegeom = $parent_geom[0]=="conoid" ? attach_geom(r=2,h=2,axis=$parent_geom[5])
: $parent_geom[0]=="prismoid" ? attach_geom(size=[2,2,2],axis=$parent_geom[4])
: attach_geom(size=[2,2,2]);
child_abstract_anchor = is_vector(child) && !two_d ? _find_anchor(child, basegeom) : undef;
childgeom = attach_geom([2,2,2]);
child_abstract_anchor = is_vector(child) && !two_d ? _find_anchor(_make_anchor_legal(child,childgeom), childgeom) : undef;
overlap = (overlap!=undef)? overlap : $overlap;
parent = first_defined([parent,from]);
anchors = is_vector(parent) || is_string(parent) ? [parent] : parent;
Expand Down Expand Up @@ -940,16 +969,42 @@ module attach(parent, child, overlap, align, spin=0, norot, inset=0, shiftout=0,
anchor_spin = two_d || !inside || anchor==TOP || anchor==BOT ? anchor_data[3]
: let(spin_dir = rot(anchor_data[3],from=UP, to=-anchor_dir, p=BACK))
_compute_spin(anchor_dir,spin_dir);
parent_abstract_anchor = is_vector(anchor) && !two_d ? _find_anchor(anchor,basegeom) : undef;
parent_abstract_anchor = is_vector(anchor) && !two_d ? _find_anchor(_make_anchor_legal(anchor,basegeom),basegeom) : undef;
for(align_ind = idx(align_list)){
align = is_undef(align_list[align_ind]) ? undef
: assert(is_vector(align_list[align_ind],2) || is_vector(align_list[align_ind],3), "align direction must be a 2-vector or 3-vector")
two_d ? _force_anchor_2d(align_list[align_ind])
: point3d(align_list[align_ind]);
spin = is_num(spin) ? spin
: align==CENTER ? 0
: sum(v_abs(anchor))==1 ? // parent anchor is a face
let(
spindir = in_list(anchor,[TOP,BOT]) ? BACK : UP,
proj = project_plane(point4d(anchor),[spindir,align]),
ang = v_theta(proj[1])-v_theta(proj[0])
)
ang
: // parent anchor is not a face, so must be an edge (corners not allowed)
let(
nativeback = apply(rot(to=parent_abstract_anchor[2],from=UP)
*affine3d_zrot(parent_abstract_anchor[3]), BACK)
)
nativeback*align<0 ? -180:0;
$idx = align_ind+len(align_list)*anch_ind;
$align=align;
goodcyl = $parent_geom[0] != "conoid" || is_undef(align) || align==CTR ? true
: let(
align=rot(from=$parent_geom[5],to=UP,p=align),
anchor=rot(from=$parent_geom[5],to=UP,p=anchor)
)
anchor==TOP || anchor==BOT || align==TOP || align==BOT;
badcorner = !in_list($parent_geom[0],["conoid","spheroid"]) && !is_undef(align) && align!=CTR && sum(v_abs(anchor))==3;
badsphere = $parent_geom[0]=="spheroid" && !is_undef(align) && align!=CTR;
dummy=assert(is_undef(align) || all_zero(v_mul(anchor,align)),
str("Invalid alignment: align value (",align,") includes component parallel to parent anchor (",anchor,")"));
str("Invalid alignment: align value (",align,") includes component parallel to parent anchor (",anchor,")"))
assert(goodcyl, str("Cannot use align with an anchor on a curved edge or surface of a cylinder at parent anchor (",anchor,")"))
assert(!badcorner, str("Cannot use align at a corner anchor (",anchor,")"))
assert(!badsphere, "Cannot use align on spheres.");
// Now compute position on the parent (including alignment but not inset) where the child will be anchored
pos = is_undef(align) ? anchor_data[1] : _find_anchor(anchor+align, $parent_geom)[1];
$attach_anchor = list_set(anchor_data, 1, pos); // Never used; For user informational use? Should this be set at all?
Expand All @@ -963,7 +1018,7 @@ module attach(parent, child, overlap, align, spin=0, norot, inset=0, shiftout=0,
* affine3d_zrot(-parent_abstract_anchor[3])
* rot(from=parent_abstract_anchor[2],to=UP)
* rot(v=anchor,-spin),
align);
align);
// The $anchor_override anchor value forces an override of the *position* only for the anchor
// used when attachable() places the child
$anchor_override = all_zero(child_adjustment)? inside?child:undef
Expand Down Expand Up @@ -3687,8 +3742,10 @@ function _find_anchor(anchor, geom) =
let(all_comps_good = [for (c=anchor) if (c!=sign(c)) 1]==[])
assert(all_comps_good, "All components of an anchor for a cuboid/prismoid must be -1, 0, or 1")
let(
size=geom[1], size2=geom[2],
shift=point2d(geom[3]), axis=point3d(geom[4]),
size=geom[1],
size2=geom[2],
shift=point2d(geom[3]),
axis=point3d(geom[4]),
override = geom[5](anchor)
)
let(
Expand Down Expand Up @@ -3737,7 +3794,6 @@ function _find_anchor(anchor, geom) =
// : oang
) [anchor, final_pos, final_dir, default(override[2],spin)]
) : type == "conoid"? ( //r1, r2, l, shift
assert(anchor.z == sign(anchor.z), "The Z component of an anchor for a cylinder/cone must be -1, 0, or 1")
let(
rr1=geom[1],
rr2=geom[2],
Expand All @@ -3747,6 +3803,11 @@ function _find_anchor(anchor, geom) =
r1 = is_num(rr1)? [rr1,rr1] : point2d(rr1),
r2 = is_num(rr2)? [rr2,rr2] : point2d(rr2),
anch = rot(from=axis, to=UP, p=anchor),
axisname = axis==UP ? "Z"
: axis==RIGHT ? "X"
: axis==BACK ? "Y"
: "",
dummy = assert(anch.z == sign(anch.z), str("The ",axisname," component of an anchor for the cylinder/cone must be -1, 0, or 1")),
offset = rot(from=axis, to=UP, p=offset),
u = (anch.z+1)/2,
// Returns [point,tangent_dir]
Expand Down
49 changes: 49 additions & 0 deletions tutorials/Attachments.md
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Original file line number Diff line number Diff line change
Expand Up @@ -681,6 +681,55 @@ prismoid(150,60,100)
show_anchors(s=45);
```

Is is also possible to attach to edges and corners of the parent
object. The anchors for edges spin the child so its BACK direction is
aligned with the edge. If the edge belongs to a top or bottom
horizontal face, then the BACK directions will point clockwise around
the face, as seen from outside the shape. (This is the same direction
required for construction of valid faces in OpenSCAD.) Otherwise, the
BACK direction will point upwards.

Examine the red flags below, where only edge anchors appear on a
prismoid. The top face shows the red flags pointing clockwise.
The sloped side edges point along the edges, generally upward, and
the bottom ones appear to point counter-clockwise, but if we viewed
the shape from the bottom they would also appear clockwise.

```openscad-3D;Big
include <BOSL2/std.scad>
prismoid([100,175],[55,88], h=55)
for(i=[-1:1], j=[-1:1], k=[-1:1])
let(anchor=[i,j,k])
if (sum(v_abs(anchor))==2)
attach(anchor,BOT)anchor_arrow(40);
```

In this example cylinders sink half-way into the top edges of the
prismoid:

```openscad-3D;Big
include <BOSL2/std.scad>
$fn=16;
r=6;
prismoid([100,175],[55,88], h=55){
attach([TOP+RIGHT,TOP+LEFT],LEFT,overlap=r/2) cyl(r=r,l=88+2*r,rounding=r);
attach([TOP+FWD,TOP+BACK],LEFT,overlap=r/2) cyl(r=r,l=55+2*r, rounding=r);
}
```

This type of edge attachment is useful for attaching 3d edge masks to
edges:

```openscad-3D;Big
include <BOSL2/std.scad>
$fn=32;
diff()
cuboid(75)
attach([FRONT+LEFT, FRONT+RIGHT, BACK+LEFT, BACK+RIGHT],
FWD+LEFT,inside=true)
rounding_edge_mask(l=76, r1=8,r2=28);
```

## Parent-Child Anchor Attachment (Double Argument Attachment)

The `attach()` module has two different modes of operation,
Expand Down

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