Struggling with Sweeps

[Chris Heath]

Hi

Along with attempting other work arounds, I've been trying for hours to get the sweep to work consistently for all spines which were imported as a PDF (exported from Affinity Designer). In Affinity Designer, I have redrawn the lines. I have reversed the curves. I don't know what else to do to get these two swept splines facing the same way as the others. It's not a problem if I use a four or eight-sided spline because when flipped around, they look the same. But for sweeping custom profiles, this is something that I would like to solve for other designs I'm planning.

One of the other attempts to get this pattern to work was to draw a quarter of the pattern and use symmetry modifiers to reflect the quadrant in both the x-axis and the y-axis. That solved the above problem, but then I ended up with having to join up the ends. I tried point slide, but could not snap them to vertical or horizontal. The snapping was always a couple of degrees off.

Any help will be greatly appreciated. I have attached one of the PDFs for reference.
This is rough draft of what I'm trying to create below for a wallpaper pattern. It's for a Spoonflower competition and due tomorrow, but I'm not fussed about missing the deadline. I'll still put this design up for sale.

I also intend to replace the n-gon shape with a custom vector shape. My first attempt was a disaster thanks to the problematic splines. Plus the profile / cross-section needs a lot more work.

Thanks in advance for any help offered.

Chris

 

[frank beckmann]

This has to be a bug or an exception not taken into account, not registered and not implemented. You can mirror or rotate 180° or duplicate from the left to the right and always will run into this issue. Or change the order of the separate paths - no cure. Weird.

 

[ZooHead]

It is weird, even separating all the splines, those two are flipped.
At least when they are separate splines you can rotate the profile splines individually.

Another workaround is to make it editable, select the flipped objects and flip them back.

 

[Chris Heath]

This has to be a bug or an exception not taken into account, not registered and not implemented. You can mirror or rotate 180° or duplicate from the left to the right and always will run into this issue. Or change the order of the separate paths - no cure. Weird.

Thanks Frank. It’s good to know that it’s not a problem between the screen and keyboard, that is, it’s not me this time. I have come across this problem before and given up. Hopefully Martin will see this thread and look into it.

 

[Chris Heath]

It is weird, even separating all the splines, those two are flipped.
At least when they are separate splines you can rotate the profile splines individually.

Another workaround is to make it editable, select the flipped objects and flip them back.

Thanks Eric. It looks like importing the splines separately and flipping those two splines is going to be the way to go for now.

I’ll also try your second suggestion.

 

[MonkeyT]

Every Spline has a flow direction, even closed loops. Have you tried using Tools -> Spline -> Reverse Sequence instead of physically flipping the entire spline? (Oops. I just saw where you reversed the curves. Sorry.)

 

[frank beckmann]

I`ve been through all of this including drawing these paths from scratch in Inkscape several times with different orders and path directions - no luck. You can try to select these nodes in a compound path in Cheetah3D quite easily - but even rotating will flip the alignmet just before you reach 180 degree. What I haven`t time to try is to import as SVG to mainatin individual path as segments, put one segment plus profile into the sweep-creator and then add one by one, call “Merge“ on them, add another segment, call „Merge“ again etc pp. I guess the last 2 will flip again.

 

[Chris Heath]

Hi Frank. Thanks for suggesting SVG. I have always used vector PDF up until today. I like how SVG brings in one path per layer, as opposed to all paths being placed in one layer.

Just to confirm that when the spline (Path 6. below) is flipped 180 degrees, the profile rotates to face the same direction like you said. Flipping Sweep 7 (not path 7) works, but then it stands proud of the other swept splines and needs to be aligned (See circled area).

 

[moooztar]

Hi Chris,

Is this what you are after?

If so: expand stroke in A.D. before exporting to SVG.

Tip for size handling: Use the default profile SVG Digital Small size (72 dpi) in A.D. and you have a ratio of 1:1 where pixels in A.D. for example 190 px = 19 cm in "C3D" as long as import factor in C3D = 0.1 for SVG

 

[moooztar]

You can then make your end lines a little longer and use a wallpaper function in a design package to make tiles.

 

[frank beckmann]

Ok - adding spline by spline to merge inside the Sweep creator isn´t working either.
What I now did is a robust modeling on just a quarter of the already mirrored pattern.
1. make sure to extend the line past the page border which we use as a cutting frame
2. even with just 4 splines 2 will flip again but reverse its sequence works this time
3. set up the Sweep and make editable
4. generate page/frame spline with extrude creator to use inside a Boolean->Intersect with the pattern mesh.
5. set up 2 symmetry and 3 array modifiers and you´ll get this:

 

[ZooHead]

Here's a method I've been playing with... part 1
On a similar track with Frank.

 

[moooztar]

If you expand different stroke widths as different splines from. A.D. and import them into a Loft it will also give nice effects to play around with. Wider stroke on the bottom and "thinner as you go" nearer the cam. Will give more creative freedom (looking at your initial pictures).

Ps. Can also try to use the bottom layer as an outlined stroke from A.D and your current spline as the top. Won't give you holes on the top then.. FYI.

 

[ZooHead]

Part 2 the Sweep Profile Rotation

 

[frank beckmann]

Ps. Can also try to use the bottom layer as an outlined stroke from A.D and your current spline as the top. Won't give you holes on the top then.. FYI.

Will this make a seamless pattern?

 

[Chris Heath]

Hi Chris,

Is this what you are after?

If so: expand stroke in A.D. before exporting to SVG.

Tip for size handling: Use the default profile SVG Digital Small size (72 dpi) in A.D. and you have a ratio of 1:1 where pixels in A.D. for example 190 px = 19 cm in "C3D" as long as import factor in C3D = 0.1 for SVG

I'll definitely give this a go. This solves a different problem for me and that is matching the units of measure in AD to Cheetah's units of measure. Spoonflower's unit of measure is inches, so even though I'm a metric guy, sticking with the inches all the way through the design process simplifies everything. Thanks so much for this advice. I'm unsure about the expanded stroke idea, but it's worth experimenting with.

 

[moooztar]

Think I figured it out for you (or at least the way I would do it)

1. I cleaned up your Affinity Designer with a clear start and end point (it is not in a loop or with "blind roads" so to speak)
2. Kept it as a line (not my initial suggestion of expanding stroke in A.D.)
3. Tried with a flower and cog spline in C3D
4. Then render and cut out the parts on the side a you have a way to make it the "gfx designer way" (tiles) as in import the rendered image to another gfx program and tile it there?

Hope it helps.

Moo.

 

[moooztar]

Ps. You can also boolean subtract the end result in C3D with a "box" to get rid of the outer part. This is where the initial suggestion of size importing is important from Affinity Designer. Then you know that you can make a square in A.D. import it and use that for the boolean subtraction to get the exact dimensions. Be aware that your initial size was 481x481. I tend to always go for even numbers so I made it 480x480 pix.

No problem working in inches or cm´s. Just when ready and you want to go to C3D copy and paste from clipboard to another document with pix set (so you keep your original) and save that out in pix rescaled. The ratio mentioned above has saved me a ton of time (I use C3D nowadays for 3D prints and have to have measurements spot on for that).

 

[Chris Heath]

Ok - adding spline by spline to merge inside the Sweep creator isn´t working either.
What I now did is a robust modeling on just a quarter of the already mirrored pattern.
1. make sure to extend the line past the page border which we use as a cutting frame
2. even with just 4 splines 2 will flip again but reverse its sequence works this time
3. set up the Sweep and make editable
4. generate page/frame spline with extrude creator to use inside a Boolean->Intersect with the pattern mesh.
5. set up 2 symmetry and 3 array modifiers and you´ll get this:

Thanks so much Frank for figuring this all out. I really like the boolean idea as a cutting frame for tidying up the corners; very elegant and this is a workflow that I can use for all my patterns. Maintaining the rectangular (in this case square) unit of repetition makes tessellation in Cheetah a lot easier. This aligns with the traditional method of drawing Islamic patterns. It provides consistency of method across the geometric design process in 2D and tessellation in 3D. I'll be working my way through your steps today.

 

[Chris Heath]

If you expand different stroke widths as different splines from. A.D. and import them into a Loft it will also give nice effects to play around with. Wider stroke on the bottom and "thinner as you go" nearer the cam. Will give more creative freedom (looking at your initial pictures).

Ps. Can also try to use the bottom layer as an outlined stroke from A.D and your current spline as the top. Won't give you holes on the top then.. FYI.

Thanks again moooztar. Lofting is something I haven't played around with yet for patterns. It's definitely worth exploring.