Glitch or consequence?

offset
bug

#1

I’d like to understand this:
In order to avoid typing dimensions when I want to round off a rectangle’s corners, I figured I’d use the Offset tool to obtain an interior corner from which to draw a circle that “touches” the two edges, since the offset is the same in both directions. Before tracing the circle, I’d use the Rectangle tool from the resulting inside corner to the pre-existant one, so as to obtain a square.
When I do this, the surface of the square disappears, and tracing a diagonal to restore that surface works only until I try to delete said diagonal. This results in the surface disappearing again, as if its apexes were no longer coplanar.
What gives?
I’m not looking for a work-around, but rather for an explanation as to why this happens.


#2

To give better explanation, you might wanna share what you are doing by uploading the .skp file. I have no problems creating rounded corners with this method, Are you using the ‘Cardinal’ points of the second rectangle to create the circle ?

I am tempted, however, to give an alternative approach :slight_smile:

Don’t use offset but use guidelines :

don’t use Circle but 2-point Arc…

or use no guides at all and adjust the radius via entity-info:

SketchUp ‘remembers’ the radius of the (edited) Arc and by double clicking in the other corners, it gets automatically rid of the outer edges of the rectangle. The trick here is to double-click.


#3

If drawing a square creates a hole then you are working at a size that is below the tiny faces tolerance.


#4

Looking at @MikeWayzovski’s first animated demo, a void appears, working with larger dimensions. Or is it a front face that is created on top of the large back face? Z-fighting? I don’t have SketchUp here at the moment.


#5

What about this?


#6

First (large) rectangle creates backface upwards, after offsetting, the smaller rectangle created in the upper left corner creates a frontface upwards.


#7

Just a test for @Wo3Dan as you can see here it is related to the one edge bug, but it is fairly predictable as it happens as you go smaller.
Not a scientific test as I’ve been driving for nine hours.


#8

Nice, but I said I wasn’t looking for a workaround, but for an understanding as to why this happens… I’m working on small parts, but with 100x the scale, to avoid the lower limits of the app"s range.


#9

Which was why I asked you to upload the file, as I had no problems with doing it by your method


#10

It might be that you missed the core issue. It’s not about a work around, it’s about appropriate workflow.
Your offset method will work but it’s not the best method.
One guideline, and a magenta inference makes what you need very quick.


#11

Yeah, I’ll definitely use this method from now on, but knowing why I get this result from my admittedly not optimal workflow, is what I was looking for.


#12

Did I not answer that earlier with a post about scale, then a post showing how the small scale effects the faces.


#13

You did, but I didn’t think that scale was the issue, given the 100x precaution I’d taken beforehand.
It now seems that I should’ve went for 1000x.
Didn’t mean to test your patience…


#14

Not at all.
If you are working at larger sizes then we need to look at why it happens.
As in alluded to in my comment to @Wo3Dan it may well be just the
known and annoying single vertex connection bug.


#15

it’s a Glitch…

it can happen at any scale and is even odder than simply not drawing a face…

john


How to repair programmatically this crazy face?
#16

There we have it;
I am now onto the “annoying single vertex connection bug”, which I hadn’t known about.
Thanks one and all…


#17

@Box, I know (and apparently @franquin did too) about the scale issue. But his question about the glitch isn’t just that. In fact the disappearing face as I see now (SketchUp open!) here has nothing to do with the scale at all. It happens at much larger scale too. I already mentioned that there may be z-fighting going on, thinking that there was a new front face created ontop of the blue (back) face. No. What happens here is that one confuses SketchUp with a new face by using only one endpoint in an existing loop. If a void happens to be created (not always) then there will be two faces overlapping and Z-fighting is going on. Select one or the other face and reverse it and you’ll see that SketchUp has been tricked. Not just by creating that opening.

@franquin, try to avoid creating new faces that only tough an existing face (while dragging) at only one corner.

added: @Box, I see that you have included the “single vertex” in a later post. +1


#18

Its like a twistet “8”, the middle intersection not recognized. SketchUp tricked by the single vertex issue.


#19

What’s the best (easiest?) way to create .gif files for this forum?
I’m somewhat limited in my ability to communicate concepts here…
Should I create another topic for this?


#20

I did a demo over here Creating GIFs to present in the forum

john