scales in an accidental perspective

[fenicotteroblu]

I have to make an accidental perspective of a scale consisting of 11 steps (such as calculation of the lift and the pawn?) with the plan of the picture passing through the edge of the scale.
I have never drawn in an accidental perspective with the tilted plane. How do you do that?
Could someone help me understand?
These are my notes, so I have to do the perspective by drawing the plant first.

 

[Tristus]

consider the oblique line as the union of the first step with the last. in the sense that the steps other are just vertical and horizontal planes in sequence. So I'd start drawing those plans. then to get the oblique line I would join with a simple pencil stroke the first step with the last, until you get what is the intradosso of the inclined insole of the scale-

that line should then be dropped a little (long the axis z) parallel to its starting position to assign a proper thickness to the inclined insole.
You probably don't even need to track that oblique line, because from the sketch it seems that the underscale is buffered, so you only have to draw the ups and the peels, then horizontal and vertical planes.