Blend tool's spine problem

[Dario88]

Hi, I'm experiencing an error with the blend spine. It changes shape when i move one of the two elements that compose the Blend. I changed spine direction and all the other parameters available in blend options but nothing appens. Any ideas? I attach a dropbox link to the screen recording of the error.

Thanks in advance

Dropbox - Illustrator blend error.mp4

[Kurt Gold]

Which version of Illustrator are you using?

Can you share a sample .ai file that contains a blend with that problematic behaviour?

[Dario88]

Illustrator version is 21.1.0 on Windows 10, the sample file attached is created on mac also with 21.1.0

Having the same behaviour on both platform let me suppose that @s_gans is right, creating polar series in Illustrator is a punch in the face

Here is the sample file. The "error" happen when you move just one of the two elements

Dropbox - sample.ai

[Kurt Gold]

This is by no means normal behaviour. Smells like a bug that only appears under certain circumstances. I haven't investigated and at the moment I don't know why it happens in this case, but you can download a sample file with a similar blend. The issue does not occur in that file, unless I'm overlooking something.

blend_001.ai.zip - Google Drive

[Vishu_Aggarwal]

This is not a Bug...there is a issue in the circular path used for blend...I looked at the path in detail and found that by mistake you have applied "Corners" to one of the points.

if you will select the circular path using direct selection tool you will find that it show a corners value of 38.49 px.

Screenshot for reference -

If you don't want to create another file than apply the Transform using the Appearance panel...which scale the object only not the path.

[Kurt Gold]

It may be a bit hasty to claim that it is not a bug.

The corners may have to to with the misbehaviour, but take a look at my sample file (see post 5). In that file you will also detect two corners (which I have not applied intentionally). Do you see the same issue? I think or I'm rather sure you don't.

Somewhere is a hidden bug, but it's rather tricky to unravel it.

[Vishu_Aggarwal]

Agree with you...I wasn't able to see the corners in your file and the file I created. Mistake from my end.

But I think its the issue in the Path of Sample file given by Dario88 because I tried many time to create the blend using new paths in the same document and none of them had similar issue.

I copy & pasted only the path given in the sample.ai file into another document and created the blend it was having the same issue given the video.

So only solution I found is applying transform as effect to scale the shapes of blend.

[S_Gans]

As far as I can tell, that behavior's what I've come to expect as normal with the blend tool. It will react to the angle of the curve, as well as the tightness of the curve. With elements of the size you're using, when you tighten the curve (whether or not you're using either spline option), your objects are going to reorder to position appropriately to the curve, especially since they're so large in relation to the entire path. What you may find you need to do is, when you remake the curve, you may need to remake the spline, and use a different number of steps.
I'd love to know if others have a better solution, but I'm thinking you're not seeing abnormal behavior...

[Kurt Gold]

Does that mean that you can reproduce the behaviour as shown in the video when you use and modify a similar blend, S. Gans?

[S_Gans]

Yes - I can, and have to mess with it, often. Unfortunately, I'm answering from my phone right now, and am not near my computer to create a video, but hope to do so if I get a break, later....

[S_Gans]

So, even though I can't get to a computer, I've been giving this some thought. I'm thinking that Kurt's blend works the way it does, because after making the blend, he used Object>Blend>(and I think the command is) Replace Spline, to make it match the circle. This creates a closed shape. This object'd only react if you changed, say, the circle to an oval, or moved a point on the circle to make a kidney shape or something.

Dario88, Looks to me like you used an open path - as I do, and that's why you're getting the response I get. With an open path, each end is going to alter the path's shape, and thereby also those blended objects that run along that path.

Perhaps the method above - make the blend, make a circle over the blend, and use the Object menu as above, may resolve the problem you're having...

[Kurt Gold]

No, in my sample file the circular path is not closed. It’s an open path as well as in Dario’s file. Otherwise I wouldn’t have called it a similar blend.

You may want to take a closer look at Dario’s blend again. Open the Layers palette and select the bottommost rectangle. Now move it just a fraction of a millimetre or scale it slightly. After that, one of the endpoints of the circular path immediately slips to what formerly was the centre point of the path.

I cannot see how one could call that normal behaviour. It’s rather completely unexpected behaviour and obviously it is a bug.

[Dario88]

Hi S_Gans sorry for the delay, i tried even with closed path, the trim path is a variation of the problem. On closed path it produce the same result. When one of the objects is modified (rotation, scale etc.) the spline change shape, it's always a closed path but with another shape.