I wonder if these useful functions would best be provided via a library,
like BOSL2.

Jon

On 4/5/2024 2:35 PM, John David via Discuss wrote:

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I would vote for that.  (or as Benny Hill, an old British comedian, used to
say: "I would buy that for a dollar")

On Fri, Apr 5, 2024 at 2:38 PM Jon Bondy jon@jonbondy.com wrote:

I had to construct exactly this for a large project, and work it into a
dimensioning module that leverages BOSL2's $parent_geom[1] to present
available dimensions for simple 3D primitives. For more complex shapes,
like custom gears, it can accept a structure-like element to produce
measurements that aren't managed (or really, exposed today) by BOSL2.

I was going to put it out as part of that project, but it probably would do
better as part of BOSL2, or at the least, as a standalone module library;
I'm largely indifferent which. Revar, if this is something you're
interested in, let's talk.

[image: measure.png]
[image: measure_2.png]
[image: measure_4.png]
[image: measure_15.png]

[1]: probably not the safest thing to depend on, but it works for me

On Fri, Apr 5, 2024 at 6:31 PM Revar Desmera via Discuss <
discuss@lists.openscad.org> wrote:

--

• Jon Gilbert
  jong@jong.org / jgilbertsjc@gmail.com

This looks really interesting.
Please share the code for the same
It would be better if this is a separate standalone library
Regards
Sanjeev

On Sat, 6 Apr, 2024, 7:14 am Jonathan Gilbert via Discuss, <
discuss@lists.openscad.org> wrote:

Sanjeev,

I am not sure if it would be better separate or integrated in.  I could see
it both ways.  I would say whatever the mechanism it would be nice (and
maybe even a requirement) for it to work well with a couple of the more
standard libraries like BOSL2 and NopSCADlib.

On Sat, Apr 6, 2024 at 8:44 PM Sanjeev Prabhakar via Discuss <
discuss@lists.openscad.org> wrote:

Seems the general need is to have it non-integrated, which is fine. I've
segmented the annotation portions into their own library, and put them all
up for release at https://github.com/jon-gilbert/openscad_annotations/ -
this include the dimensional measurements posted earlier, along with
general annotations on shapes, mechanical annotations that detail movement,
and (my favorite) individual part numbering and automatic expansion of
joined parts.

Take a look and let me know what you think. If you find the modules useful,
I'd love to know. If you've got issues with them, I'd love to know that
also: the github issues tab is the best way to get those thoughts to me.

Cheers :D

On Fri, Apr 5, 2024 at 6:43 PM Jonathan Gilbert jong@jong.org wrote:

--

• Jon Gilbert
  jong@jong.org / jgilbertsjc@gmail.com

On 4/5/2024 11:35 AM, John David via Discuss wrote:

There is not, and for the reasons I gave in my comments it isn't even
obvious how to add it.

Conceptually, PR#4478 might help.  You might have a mechanism to drop
"markers" into the geometry, and then if you use the added-by-4478
"render" function it could make those positions accessible as part of
the results.

As for what I've done... I assume that you're interested in the
floorplan dimension markings.

Those are pretty straightforward, just generating geometry.  They're
buried in a larger project, with no effort to library-ize them, but you
should be able to get the idea from snippets below.  Note that $floor
gives the height of the floor and $floorplan is true to generate a 2D
representation.  I don't see any other dependencies, but let me know if
there's something you can't figure out.

module dim3(a, b, rot=0, h=10, r, d=1, label) {
a = make3(a);
b = make3(b);
r = default(r, default(d, 1)/2);
d = default(d, r2);
p = topolar(b-a);
label = default(label, str(round(p[0]/inch), """));
cone_r = r2;
cone_h = r4;
translate(a) rotate([0,p[2],p[1]]) {
translate([0,0,cone_h]) cylinder(h=p[0]-cone_h2,r=r);
translate([0,0,p[0]-cone_h]) cylinder(h=cone_h, r1=cone_r, r2=0);
cylinder(h=cone_h, r1=0, r2=cone_r);
rotate([0,-90,0])
rotate([rot,0,0])
linear_extrude(height=r2, center=true)
translate([p[0]/2,r1.2,0])
text(label, size=h, halign="center", valign="bottom");
}
}

module dim2(a, b, h=10, r, d, label) {
a = make2(a);
b = make2(b);
r = default(r, default(d, 1)/2);
d = default(d, r2);
p = topolar(b-a);
label = default(label, str(round(p[0]/inch), """));
cone_r = r3;
cone_h = r4;
translate(a) rotate(p[1]) {
translate([cone_h,-r]) square([p[0]-cone_h2,d]);
translate([p[0]-cone_h,0]) rotate(-90) trapezoid(h=cone_h, w1=cone_r2, w2=0);
rotate(-90) trapezoid(h=cone_h, w1=0, w2=cone_r2);
translate([p[0]/2,r*1.2])
text(label, size=h, halign="center", valign="bottom");
}
}

module dim(a, b, h=10, r, d=1, label) {
if ($dims) {
if (!is_undef($floorplan) && $floorplan) {
dim2(a=a, b=b, h=h, r=r, d=d, label=label);
} else {
translate([0,0,is_undef($floor) ? 0 : $floor])
dim3(a=a, b=b, h=h, r=r, d=d, label=label);
}
}
}

function default(val, def) = is_undef(val) ? def : val;

module trapezoid(h, w, w1, w2) {
w1 = default(w1, w);
w2 = default(w2, w);
polygon([
[-w1/2, 0],
[-w2/2, h],
[w2/2, h],
[w1/2, 0]
]);
}

// Given an [x,y] or [x,y,z], transform to a
// [rho, theta] or [rho, theta, phi].
// Note that in mathematical spherical coordinates,
// phi is measured down from vertical.  This is as
// opposed to geographic coordinates, where latitude
// is measured up from the equator.
function topolar(p) =
len(p) == 3 ? topolar3(p) : topolar2(p);

function topolar2(p) = [
norm(p),
atan2(p.y, p.x)
];

function topolar3(p) = [
norm(p),
atan2(p.y, p.x),
atan2(norm([p.x,p.y]), p.z)
];

// @brief      Given an [x,y] or an [x,y,z], return an [x,y,z].
// @param  a  A two- or three- element array
// @returns    A three-element array
function make3(a) =
assert(len(a) == 2 || len(a) == 3)
len(a) == 3 ? a : concat(a, 0);

// @brief      Given an [x,y] or an [x,y,z], return an [x,y],
//              discarding z.
// @param  a  A two- or three- element array
// @returns    A two-element array
function make2(a) =
assert(len(a) == 2 || len(a) == 3)
[ a[0], a[1] ];