Allow drawing lines with specific angles

[inkreasing]

This is currently possible only if the line starts at the origin (0, 0) by using polar coordinates as the second position. But if you want to draw a line starting at a different position that doesn't work. (or at least i didn't find a way)

It could work by allowing the polar coordinates to specify the origin. I am unsure how to make that ergonomic for the case of a line, where the origin should be the start of the line.

[inkreasing]

I learned that it is possible to do this using the interpolation coordinates using the angle property. This is not really ergonomic, but it works.

[johannes-wolf]

You can use relative coordinates in combination with polar coordinates:

#canvas({
  import draw: *
  rect((0,0), (5,5))

  line((1,1), (rel: (30deg, 1))) // ← The second coordinate is relative to the previous one.
})