Hi, I've been measuring some buildings, by walking around the sides
with a tape measure. I've recorded the measurements in a notebook,
with a rough outline. The easiest way I can think of is entering the
data is as a comma separated string, something like "e500, n30,e70.5,
e80", etc. where the letters signify direction, east, west, north,
south (assuming building is square, but maybe it needs a rethink, with
just a compass bearing in degrees, say, instead of the letters - would
be useful for bay windows, etc.) However, in order to get an external
floor plan, I need it to be converted to a list of vectors - in the
above example it would be [[500,0],[530,30],[570.5,30],[650.5,30]] (If
I've added it up correctly). However, I'm struggling to do that within
openscad.

The number of measurements involved, makes it tedious to enter the
list syntax directly. Any ideas on how to do the conversion within
openscad? I want to minimise the keystrokes for data entry.

Best wishes,

Ray

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Hi, I've been measuring some buildings, by walking around the sides
with a tape measure. I've recorded the measurements in a notebook,
with a rough outline. The easiest way I can think of is entering the
data is as a comma separated string, something like "e500, n30,e70.5,
e80", etc. where the letters signify direction, east, west, north,
south (assuming building is square, but maybe it needs a rethink, with
just a compass bearing in degrees, say, instead of the letters - would
be useful for bay windows, etc.) However, in order to get an external
floor plan, I need it to be converted to a list of vectors - in the
above example it would be [[500,0],[530,30],[570.5,30],[650.5,30]] (If
I've added it up correctly). However, I'm struggling to do that within
openscad.

The number of measurements involved, makes it tedious to enter the
list syntax directly. Any ideas on how to do the conversion within
openscad? I want to minimise the keystrokes for data entry.

Best wishes,

Ray

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

Hi, I've been measuring some buildings, by walking around the sides
with a tape measure. I've recorded the measurements in a notebook,
with a rough outline. The easiest way I can think of is entering the
data is as a comma separated string, something like "e500, n30,e70.5,
e80", etc. where the letters signify direction, east, west, north,
south (assuming building is square, but maybe it needs a rethink, with
just a compass bearing in degrees, say, instead of the letters - would
be useful for bay windows, etc.) However, in order to get an external
floor plan, I need it to be converted to a list of vectors - in the
above example it would be [[500,0],[530,30],[570.5,30],[650.5,30]] (If
I've added it up correctly). However, I'm struggling to do that within
openscad.

The number of measurements involved, makes it tedious to enter the
list syntax directly. Any ideas on how to do the conversion within
openscad? I want to minimise the keystrokes for data entry.

On 6/24/2024 12:37 PM, Raymond West via Discuss wrote:

Hi, I've been measuring some buildings, by walking around the sides with a
tape measure. I've recorded the measurements in a notebook, with a rough
outline. The easiest way I can think of is entering the data is as a comma
separated string, something like "e500, n30,e70.5, e80", etc. where the
letters signify direction, east, west, north, south (assuming building is
square, but maybe it needs a rethink, with just a compass bearing in
degrees, say, instead of the letters - would be useful for bay windows,
etc.) However, in order to get an external floor plan, I need it to be
converted to a list of vectors - in the above example it would be
[[500,0],[530,30],[570.5,30],[650.5,30]] (If I've added it up correctly).
However, I'm struggling to do that within openscad.

The number of measurements involved, makes it tedious to enter the list
syntax directly. Any ideas on how to do the conversion within openscad? I
want to minimise the keystrokes for data entry.

For a non-DIY solution, consider BOSL2's turtle-graphics function:
https://github.com/BelfrySCAD/BOSL2/wiki/drawing.scad#function-turtle

ISTM that there are approximately three steps to the problem you're
describing.

- Converting a string like "e500, n30, e70.5, e80" into something more
directly usable, like a list of compass bearings and distances.
- Converting a list of compass bearings and distances into a list of
Cartesian relative positions.
- Converting a list of Cartesian relative positions into a list of
Cartesian absolute positions.

For my own house model, my biggest tool was my "vector" function:

function vector(origin, dir, length) = polaradd(origin, fromcompass(dir), length);
function polaradd(origin, dir, length) =
[origin[0] + cos(dir)*length, origin[1] + sin(dir)*length];
function fromcompass(a) = normalize_angle(90+360-a);
// Normalize an angle so that it is between 0..360
function normalize_angle(a) = (a%360 + 360)%360;

so if I was describing the path you described above, it would end up
something like:

p1 = [0,0];
p2 = vector(p1, 90, 500);
p3 = vector(p2, 0, 30);
p4 = vector(p3, 90, 70.5);
p5 = vector(p4, 90, 80);

That's a very verbose representation, but (a) the typing was only a very
small fraction of the cost, and (b) it allowed me to base multiple "next"
points on a single point.  That is, if I needed to also go west from
point 3, that was straightforward.  I can provide additional details on how
I represented walls if you like.

But going back to your question...

- Converting a string like "e500, n30, e70.5, e80" into something more
directly usable, like a list of compass bearings and distances.

I would do this in preprocessing, rather than trying to do it in OpenSCAD
per se.  You certainly can do such things in OpenSCAD, but it is no fun
at all.I would use an editor (vi, sed, et cetera) or maybe a text-friendly
programming language to add in the brackets and turn "eNNN" to "90, NNN".

- Converting a list of compass bearings and distances into a list of
Cartesian relative positions.

cartesian_relative = [ for (p=polar_relative) p[1] * [cos(p[0]), sin(p[0])] ];

- Converting a list of Cartesian relative positions into a list of
Cartesian absolute positions.

This is a variation on the classic "running sum" problem, which is never
any fun.  (But not quite common enough or un-fun enough for me to have a
stock solution anywhere.)

Here's a solution, though I'm not entirely happy with it.  I think it
can be optimized a bit but don't have the energy right now:

function runningSum(a, i=0) =
[
a[0],
for ( i = 0, t = a[0]; i+1 < len(a); i=i+1, t=t+a[i]) t + a[i]
];

Notes:

- I didn't want to have it know what type the array is - it should be
anything that you can add:  numbers, vec2s, vec3s, et cetera.
- It needs to emit the last entry *without* stepping past the end of
the array.

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I can't help but wonder how many sides does this building have such
that the time spent researching this will be less than the time to
just type out the long version.  :)

Thanks for all your replies.  I've decided to go with Steve'sidea "A
quick and lazy way that I think would work" which at the moment suits
me fine, except the summing of the elements is going to need a
recursive function, at least, which tends to bother me. If I'm happy
with it, I'll post the code.

So far, excluding windows and doors, for the exterior of the building,
there are about 60 points to play with, but later, once the proof of
concept is completed, I will probably persuade ChatGPT to write some
python code, or something, to simplify all the data entry. ChatGPT is
OK at Python, at least for my purposes, but not so good with openscad,
where it becomes a battle of wills.

Best wishes,

Ray

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Here's the code, for the north facing wall, and a bit of the two sides.
Thanks for the help. (and ChatGPT, who got there in the end)

// points from wall distances
n=[0,1];s=[0,-1];e=[1,0];w=[-1,0];
p=
[e0,w8.5,s38,w5,w95,w110,w50,w4,n37,w75,n7,w44,s8,w52,w62,w70,w39,w69,w43,s90,e*726.5];

function build_new_list(p, new = [[0, 0]]) =
len(new) > len(p) ? new :
let (last = new[len(new) - 1],
next = [last[0] + p[len(new) - 1][0], last[1] + p[len(new) -
1][1]])
build_new_list(p, concat(new, [next]));

    new = build_new_list(p);
       echo(old=p);
      echo(new=new);

      polygon(new);

////////////////////////////////////////////////////
On 25/06/2024 12:41, Raymond West via Discuss wrote:

Thanks for all your replies.  I've decided to go with Steve's idea "A
quick and lazy way that I think would work" which at the moment suits me
fine, except the summing of the elements is going to need a recursive
function, at least, which tends to bother me. If I'm happy with it, I'll
post the code.

So far, excluding windows and doors, for the exterior of the building,
there are about 60 points to play with, but later, once the proof of
concept is completed, I will probably persuade ChatGPT to write some python
code, or something, to simplify all the data entry. ChatGPT is OK at
Python, at least for my purposes, but not so good with openscad, where it
becomes a battle of wills.

Best wishes,

Ray

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org

OpenSCAD mailing list
To unsubscribe send an email to discuss-leave@lists.openscad.org