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Keet
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Large wall tilts when curved. Math error?

I wanted to create a curved car ramp to an upper level 3.50m higher by using a thick and long wall that I could export as an object.
What happens is that curving the wall causes the wall to tilt a little. This is easy to reproduce:

Draw a wall 40 meters long and 5 meters wide. Now give it a slope from 0.1cm to 350cm and curve it in a 90° angle. What happens is that the wall tilts with half of the the width disappearing into the ground. You can see that when looking at the low end in 3D view. I put a little box at the low end to see how large the height difference was: The tilt is quite extensive when using such a large wall, more than 3cm above and below the ground level.

I assume this happens as the result of using the center of the wall as the calculation center. I think it is a mathematical error when the wall curve is calculated for 3D view because both the top and the ground level should always remain horizontal. Overall not a problem for what I intended to do. I can either live with it or use another program to draw the ramp but the better solution would be to revise the wall calculation so remove the tilt.

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Debian 10 (Mate desktop)
Sweethome3D v6.4.2.
[Apr 8, 2022, 8:32:13 AM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
Keet
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Re: Large wall tilts when curved. Math error?

It's worse than I thought: Split a sloped wall and a angle one part to create a corner and the tilt occurs there too, viewable at point where the two wall parts connect.
That will occur much more often but will probably not be noticed with 'normal' sized walls because the difference will be small.
Emmanuel, any way this can be resolved? Should I report this as a bug?
[Apr 8, 2022, 4:11:08 PM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
Puybaret
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Re: Large wall tilts when curved. Math error?

Actually, I'm more bothered by your second post, but I'm not sure of the best solution to apply. If the corners of sloping wall join the corners of the flat wall, the 4 points of the wall top won't be coplanar and this won't be correct too.
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Emmanuel Puybaret, Sweet Home 3D developer
[Apr 8, 2022, 5:17:28 PM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
Keet
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Re: Large wall tilts when curved. Math error?

I didn't think it would be easy or that it wouldn't create a different problem 'on the other side' sad

For others encountering this problem:
For my current situation, a car ramp, I have solved it by having 2 straight slopes and a flat 90dg curve at half height in between. Not a smooth decline all the way but for my current project it works just as well.
Export the three parts together after setting different colors for sides and top. Edit the obj and mtl file to change the material properties to 'Sides' and 'Top' and change the naming 'wall' to 'ramp'.
This gives a very clean object after import as "Car Ramp".
While busy I created the same object with a 30° and 45° angle too.
28kB for an object that spans over 33mx33m in the plan.

I'm not sure if there's a solution for the sharp corner with a sloping wall. Maybe use a square flat piece of wall at the corner with width and length of the sloping walls. Not perfect but probably better than the tilted tops.
[Apr 8, 2022, 5:59:06 PM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
Puybaret
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Re: Large wall tilts when curved. Math error?

In case you didn’t see it, there’s also a quarter slope among the free models.
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Emmanuel Puybaret, Sweet Home 3D developer
[Apr 8, 2022, 7:03:53 PM] Show Printable Version of Post    View Member Profile    Send Private Message [Link] Report threatening or abusive post: please login first  Go to top 
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