Both "flip" Y commands give unexpected results.

[ScreenDream]

I recently converted my Creality Ender 5 Plus 3D printer running Klipper to a pen plotter.
I was recommended vpype and got things working with a custom config using vpype-gcode.

I create my designs using SideFX Houdini, export as SVG and do the final scaling and positioning on an A4 page in Inkscape.

Everything was working great, but the Y placement of the prints was wrong and different for each design.

At that time I was using "invert_y = true" from an example to compensate for the inverted axis on the printer.
-> It felt as if the print was always moved to the upper end of the print area depending on the content, no matter where the design was placed in the A4 page in Inkscape.

Then I investigated further and tried to use "vertical_flip = true" which gave me different, but also unexpected and inconsistent results that did not make sense to me.

vpype itself does exactly what I want, I checked that with the integrated viewer.

My commandline looks like this:
vpype read E:...\InputFile.svg linemerge linesort reloop linesimplify gwrite --profile Ender5Plus E:...\OutputFile.gcode

I then tried not using any of the flip commands in the gcode config and flipping my design in Inkscape instead.
This also works perfectly as expected.

I am using these offsets when not using the flip commands:

[gwrite.Ender5Plus]
unit = "mm"
offset_x = 50
offset_y = 44

So what I would expect to happen:

• I set my offset to whatever I need for my printer to work correctly.
• I use a flip command in Y and vpype-gcode flips the design in Y around the center of the SVG-defined page/viewport, so that an A4 design that fills the page will do so after the flip as well.
• This should be Independent from the offset.

So internally I would think that first the design is flipped inside of the page boundaries and then the whole thing is offset.

I found other users with the same problems on the drawingbots discord BTW.

Thanks for any insights.
It would be great if this could be made to work.

Thanks you for this tool! Other than this issue, it is fantastic! :-)