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Round walls aren't round?
Emmanuel,
I always wanted to make a spiral staircase like this one:
So, I devised a way to make it in SH3D using round walls. This is how I did it: - draw a round wall with an angle of 180 degrees - correct XY coordinates to exact round numbers - make it sloping from 300 to 0.1 cms - then use CopyAsNewFurniture, Paste, Export to OBJ format - Import furniture twice, rotating the second model so that it's upside-down. - stack the two objects, and voila.
It's only then that I discovered that (1) round walls aren't perfectly round or (2) that I must have done something wrong. The image below shows a clear band on the left where the top and lower half don't line up.
Do you have a solution?
Hans
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Hans
France
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Re: Round walls aren't round?
Round walls are not really round (anyway roundness doesn't exist in Java3D and OpenGL which handle only triangles) and you can see how many points are used to approximate a round wall when you double-click to create a room surrounded by round walls. If you look closer to the points of the room created that way, you'll guess that the wall aren't generally symmetric and that's why you get the problem you reported. So, either you try to change wall length and/or thickness step by step until it's symmetric, or with the (quite complicate) following formula used to compute the step between two points of a round wall, try to find which thickness, arc extent, and/or radius will give you an integer (with no decimals):
step = squareRoot( (thickness/2 + radius) x arcExtent x π / 180)
For example, it works for a wall thickness of 14.776 cm, a radius of 120 cm and an arc extent of 180°.
Suddenly, I feel you hate me!
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Emmanuel Puybaret, Sweet Home 3D creator
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Re: Round walls aren't round?
Emmanuel,
Now, why should I hate you for helping me? I can manage a spreadsheet, so I could solve your puzzle, as the picture proves. The shadow on the top-edge isn't perfect, but I can't change that. It's a nice one for Tips & Tricks.
France
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Re: Round walls aren't round?
Thank you for creating such a spreadsheet. But I'll try to fix it in the program, to ensure round walls will always be symmetric.
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Emmanuel Puybaret, Sweet Home 3D creator
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Re: Round walls aren't round?
Emmanuel,
After solving "The Riddle of the Round Walls and the Climbing Spiral", I was (once again) trying to make a helical staircase.
After saving my design, which still included help parts and such, I checked the file size and found that is was about 600 Kb. I then deleted all the stuff I didn't need, and only kept the model you can see in the image above. To my surprise the file size still was 470 Kb.
This means that a 130 Kb basic design, somehow swells to 470 Kb just becasue of applying CopyAsNewFurniture and Export to OBJ format. I attach the file, so you can check my design and data.
France
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Re: Round walls aren't round?
I'm not astonished by that. CopyAsNewFurniture plug-in transforms a simple Wall Java object which is less than 100 bytes in a PieceOfFurniture Java object bound to an OBJ file describing the many faces of an arc.
By the way, did you save your file with the Save and compress menu item, to see if it's still big?
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Emmanuel Puybaret, Sweet Home 3D creator
Netherlands
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Re: Round walls aren't round?
Emmanuel,
Thanks for your explanation.
When I Save & Compress, the "dirty" file becomes 201 Kb (instead of 595) and just the helical staircase shrinks from 468 Kb to 124 Kb.
For a staircase a growing file isn't a big problem, most homes only have one. But for a repeating model (chair or table in a restaurant?) it would make a big difference.
Now I know what the reason is, I hope I can sleep well :-)
Hans
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Hans
France
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Re: Round walls aren't round?
From the current beta version 3.1, unjoined new round walls are always symmetric. As the CopyAsNewFurniture plug-in can't work with Java Web Start, you won't be interested that much by this feature but it will be a nice to have for the next release. I didn't change the way round walls created with version 3.0 were computed to ensure they look exactly the same.
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Emmanuel Puybaret, Sweet Home 3D creator
Netherlands
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Re: Round walls aren't round?
Emmanuel,
I'm not sure that I understand your message. Does it mean that new walls will automatically follow your formula? We won't need this spreadsheet model anymore?
EDIT I constructed a semi-circle in v3.0 and imported it in v3.1b13. Then I constructed the same semi-circle in v3.1b13, and it lines up perfectly with the imported one. That suggests they are based on the same mathematical <?> principles.
Hans
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Hans
new website - under constuction hansdirkse.info
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[Edit 1 times,
last edit by hansmex at Jan 26, 2011, 10:59:05 AM]
