Invert Y axis for the whole document

[brianlow]

I'd like to draw SVGs in the same orientation they will appear on the plot.

My plotter's origin is bottom left.

I am finding invert_y: true flips a shape along the shape's center (or more precisely, along the center of all shapes combined).

Is there an option to flip along the document's center?

Steps to Reproduce

``` vpype --config "${PWD}/vpype.toml" read t.svg gwrite --profile default t.gcode ``` vpype.toml: ```toml [gwrite.default] invert_y = true segment = "x X{x:.4f}, y Y{y:.4f}\n" ``` t.svg: ```svg ``` t.gcode: ```gcode x X3.1525, y Y172.0001 x X6.3050, y Y165.3495 x X0.0000, y Y165.3495 x X3.1525, y Y172.0001 ``` ^^^ expected the Y coordinates to be close to 0

[tatarize]

I believe there is one but it would need to be in vpype actual, since I believe the document itself needs to be flipped. Though if you know the size of the document you could offset by the document height. But, vpype-gcode isn't given the document size information. @abey79 how/where is that document info stored.

This is entirely correct, the coordinate system for gcode is typically origin in bottom-left rather than origin in upper-right. IS there a flip within document code that does this correctly? Because vpype gcode doesn't know the actual document size to do that math (or I dunno how to access it exactly.

[brianlow]

Thanks! That pointed me in the right direction:

vpype  ...
   read ...
   scale --origin 0 86mm -- 1 -1     # 86mm is the document center
   gwrite ...

# in .toml
invert_y = false

I know the document size before hand (it is my plotter's printable area):

Closing because solved.

Would be interested in a solution without hardcoded center if anyone finds one. The stat command knows the document size so might be something there:

========= Stats ========= 
Current page size: (783.0, 651.0)
Totals:
  Global properties:
    vp_page_size: (783.0, 651.0)