CONSTRUCTION OF A BOX WITH RAISED LID, IN OBLIQUE PERSPECTIVE.
The environment is in parallel perspective.
First of all, we construct the box in the desired dimensions. It is the same process used in former constructions in oblique perspective. We use the width, depth and height measurement lines, including the point on the horizon line.
To construct the inclined lid we sketch a vertical horizon line on the vanishing point 1. Then, we draw the box lid in vertical position. See figure 50, letter A. This vertical lid will have the same width and length dimension of the box already drawn. Construct the angle of the course of the lid from vertex a of the box lid to vertex b of the box. Mark the desired opening in this angle and by the vanishing point 2 sketch the line c. From point d in the lid opening angle, sketch a line up to point a, proceeding until reaching the vertical horizon line. Mark the vanishing point X there. From this vanishing point X up to vertex e of the vertical lid, proceeding up to crossing with line c, mark the point f there, referring to the width of the inclined lid. From point f to point g, that is the vertex of the box, sketch a line up to the vertical horizon line and mark the vanishing point Y. Calculate the height of the box lid on the depth measurement line. See figure nº 50 (next page).