To draw an inclined figure in an environment, we should construct a box with the inclination desired.
The edges of the inclined box will function as height and width measurement lines. The depth is obtained with the depth point located on the fake horizon line. Please note that the distance of same from the vanishing point is the same distance existing in the larger box.
Please note that the inclined box is not leaning on the floor.
Figures 23 and 24 (next pages).