Sweet Home 3D Forum
»  List all forums
» »  Forum: Features use and tips
» » »  Thread: Splitting sloping walls?
Print at Dec 19, 2025, 4:17:07 PM
Posted by macfrog at Jan 18, 2011, 9:48:59 PM
confused   Splitting sloping walls?
When i split a wall, this is happened always(?) in the middle of it. this is fine, because i can move the splitpoint - unless i want to split a sloping wall.
in this case my newly separated walls keep their start/end height from the splitpoint. which is useless in most cases, even if i move the splitpoint to the needed coords i will still have to hassle with angles not corresponding et cetera (i got a workaround but it sucks).
so,
is there a kb shortcut to determine the point a wall will split?

thx in advance
macfrog

Posted by Puybaret at Jan 18, 2011, 10:03:23 PM
Re: Splitting sloping walls?
Sorry, there's no short cut for that.
----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator

Posted by hansmex at Jan 18, 2011, 10:09:20 PM
Re: Splitting sloping walls?
macfrog,

The shortcut involves the keyboard of a calculator, I'm afraid :-)

Hans
----------------------------------------
Hans

new website - under constuction
hansdirkse.info

Posted by macfrog at Jan 18, 2011, 10:27:12 PM
Re: Splitting sloping walls?
hansmex,
>The shortcut involves the keyboard of a calculator
not always: i put a new wall (90 degrees off) to the wanted splitpoint, make this "helpwall" big as needed and store the wanted height for this splitpoint that way. it's not funny but it works.

too bad anyway, i was hoping to get an aswer like "hold down ALT+SHIFT then click mouse button into wall" :-)

It's not an architectural program, i know... Not YET ;-)
macfrog

Posted by hansmex at Jan 18, 2011, 11:00:16 PM
Re: Splitting sloping walls?
macfrog,

That's an ingenious but simple workaround.

I spent the last (half) hour reading on all kinds of geometry websites, trying to figure out if I could make a simple spreadsheet model that would allow inputting basic data, and resulted in giving the correct measures for the split wall.

Unfortunately this is far beyond my mathematical insight. Maybe, after all, I should have paid more attention during high school...

Hans
----------------------------------------
Hans

new website - under constuction
hansdirkse.info

Posted by Puybaret at Jan 18, 2011, 11:15:03 PM
Re: Splitting sloping walls?
Applying Intercept theorem (théorème de Thalès en français) between the walls length on the floor and their height should help you. wink
----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator

Posted by hansmex at Jan 19, 2011, 2:21:33 AM
Re: Splitting sloping walls?
Hello :-)

It took me some time to intercept the meaning of the theorem, but here it is...



To calculate D (the height at the point where the wall is split) you do this simple math:

D = A / ( B/C )

So, first divide B by C
Then, divide A by that result.

Hans
----------------------------------------
Hans

new website - under constuction
hansdirkse.info

Posted by Puybaret at Jan 19, 2011, 8:14:20 AM
Re: Splitting sloping walls?
Thank you Hans for the drawing. I was sure you were able to understand the first theorem I learnt at school! wink
----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator

Posted by macfrog at Jan 19, 2011, 8:56:09 PM
Re: Splitting sloping walls?
Hello,

i just want to let you see the reason for this thread:

keep in mind: for changing a wall's texture of a given room, i have to split walls on room limits.
so, moving a wall forces me to split the aligning wall (again, and again)... so far for the calculating method, hans biggrin

screenshot below:



it's the upper level of a house with 10+ sloping walls, almost NEVER splitted in the middle. as you can see, the roof is missing wink
macfrog

Posted by wrosun at Jan 20, 2011, 7:31:18 AM
Re: Splitting sloping walls?
I like your model and can think about the hard work you have done to complete it but where is the problem???

is it solved already or are you trying to say that the things the experts said dint work or are you showing us the result after applying the solutions?

Posted by macfrog at Jan 20, 2011, 7:24:07 PM
Re: Splitting sloping walls?
hi wrosun,

the "problem" was already solved before i started this thread. in first msg i wrote "i got a workaround" and i was asking for something easier i might have overseen.
i posted the picture just to let anybody see i donot ask for no reason; especially hans is very helpfull and spend some night with other peoples problems.
oh, and thanks for liking my model :)

Posted by okh at Feb 10, 2015, 8:19:45 AM
Re: Splitting sloping walls?
...intercept the meaning of the theorem...
Thanks Hans for your theorem interception, very useful. I think you mention something about doing the math in your much used roof guide. So as a hint, I took the liberty of putting a pointer to various calculations in SourceForge, feature-requests 684.

Maybe it is worth making a list of the most useful calculations for all of us who where not subjected to French maths in school? For instance, how to calculate the values indicated here, and probably a few more that I did not think of:
ok

[/

Posted by Puybaret at Feb 12, 2015, 8:54:38 AM
Re: Splitting sloping walls?
In your drawing, intercept theorem says that:

4.5 / (3.4 - 1.6) = 2.2 / (2.48 - 1.6)

as you probably look for the 2.48 height here, the previous formula isn't very handy, but you can change it like this:

2.48 = 1.6 + 2.2 x (3.4 - 1.6) / 4.5

If you replace 1.6 by heightAtStart, 3.4 by heightAtEnd, 4.5 by distanceBetweenStartAndEnd and 2.2 by distanceFromStart, you get:

intermediateWallHeight = heightAtStart + distanceFromStart x (heightAtEnd - heightAtStart) / distanceBetweenStartAndEnd


Note that (heightAtEnd - heightAtStart) / bothWallsLength is a factor that could reapply elsewhere on walls with the same slope. This factor is also equal to tangent of 21.8°. Thus, if you know the 21.8° angle of the slope, you can also use:

intermediateWallHeight = heightAtStart + distanceFromStart x tan(slopeAngle)

If you want to calculate that angle, just reverse the formula:

slopeAngle = arctan((heightAtEnd - heightAtStart) / distanceBetweenStartAndEnd)


You might also wonder how to compute the 4.85 roof length. This time, it's Pythagorean theorem that will give you the answer because angles between walls and the floor are right:

4.85² = 1.8² + 4.5² = (3.4 - 1.6)² + 4.5²

If you replace 1.6 by heightAtStart, 3.4 by heightAtEnd and 4.5 by distanceBetweenStartAndEnd, you get:

roofLength² = (heightAtEnd - heightAtStart)² + distanceBetweenStartAndEnd²

or:

roofLength = sqrt((heightAtEnd - heightAtStart)² + distanceBetweenStartAndEnd²)

where sqrt is the square root.

Hope this will help smile
----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator

Posted by okh at Feb 12, 2015, 8:07:27 PM
Re: Splitting sloping walls?
Thanks a lot for this - and mostly for always paying attention to detail and answering every question. But I do feel guilty, it was not my intention to ask you to take the time to make the list. Checking my Pythagoras and basic trigonometry would certainly not do me any harm (even if I embarrassingly had to look up tangent being opposite/adjacent). That said, your explanation is, of course, better. And in any case, it always makes sense to check the maths of lawyers smile (As the joke goes: What can a goose do, a duck cannot, and a lawyer should? - Answer is where they can stick their bill...).

Anyway, this is the image I intended to post, trying to summarise hansmex' and the other posts on slopes and angles. Probably with unforgivable (and possibly erroneous) simplifications...

ok

Posted by Puybaret at Feb 13, 2015, 11:23:46 AM
Re: Splitting sloping walls?
Don't worry, I'm glad you found my answer useful smile
Just a small detail that bothers me on your drawing: visually, the ends of the green line don't seem to measure the top and the bottom of the same wall. You should add a small green line to join the top of intercepting wall. Hope you see what I mean...
----------------------------------------
Emmanuel Puybaret, Sweet Home 3D creator

Posted by okh at Feb 13, 2015, 4:53:14 PM
Re: Splitting sloping walls?
Yes, it bothered me too. I meant to move the entire green line, but forgot in the haste. Work in progress. To be improved. Thanks.

Posted by okh at May 13, 2015, 8:21:15 AM
Re: Splitting sloping walls?
Hmm, I did update the image, but forgot to link it here, still a rough sketch, though:

Posted by mazaya at May 28, 2015, 9:59:51 AM
Re: Splitting sloping walls?
That's an ingenious but simple workaround

Posted by okh at Jun 7, 2015, 9:37:07 AM
Re: Splitting sloping walls?
A different take on the same issue continued in thread 5953 with an interactive tool: Sloping wall intercept ok


RSS feeds
Powered by mvnForum 1.2.2 GA
© Copyrights 2002-2010 by MyVietnam.net
Current timezone is GMT
Dec 19, 2025, 4:17:07 PM