i am trying to draw a 3D-Rectangle that is rotated by say 45 degrees around its longitudinal axis. How can i achieve this? It is suprisingly difficult to draw such that it doesn't look akward.
It can be drawn only approximately because the wanted rotation (no scaling nor shifting!) would require points which do not exist in the grid, no matter how much denser it was. There's irrational number coordinates.
If you allow a little scaling and changing the proportions + shifting to let a couple of edges to fit into the grid you may draw this (=the red one, green lines are only for help):
Essentially the squareroot of 2 is rounded to 1,5
You can move it 2 or 3 grid minor divisions leftwards to make it fit as closely as possible to the original and still keep the corners in grid points. I drew it too far right only because it was marginally easier.