It would be very useful to be able with Rebelle to quickly inscribe an ellipse inside a tetragon. For example, aperspective ellipse guide à-la Krita, where one draws an ellipse in perspective by defining the four vertices of a tetragon which the ellipse is tangential to, or in a perspective as an ellipse representing the perspective transformation of a circle.
To me, the best guide to draw ellipses in perspective is Krita's, followed closely by Procreate's way of doing things.
Here's an exerpt from Kirta's user manual (https://docs.krita.org/en/user_manual/painting_with_assistants.html):
The assistant consists of four points, which are the corners for the tetragon defining the ellipse.
The X-like marks show the locations of the vanishing points for the perspective.
There are two sets of lines inside the ellipse: one, solid, are the lines connecting points where the ellipse touches the tetragon. They are the axis of the circle in perspective. The dotted lines represent the current, actual axis of the final ellipse.
One account,
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