Figure nº 20 shows how to incline a cube in parallel perspective. Please note that the dotted cube is constructed according to the normal horizon line. The inclination is obtained by descending the cube face as shown in Cube A figure or raising the face as shown in figure B.
Please note that the depth of the inclined cubes (which is the same depth of the normal cube) and the vertex of the inclined face are the key points to find the inclination point on the vertical horizon line.
Figure nº 21 illustrates the inclined cubes and the lines and points created with the inclination.
Figure nº 22 illustrates several cubes; some of them incline to the right and the others incline to the right.
We can see here the rotation of the horizon line transforming the vanishing point into axis for the proper operation.
Figure nº 23 illustrates the necessary steps to be taken when the object in inclination needs the height and width measurement lines to be drawn in millimeters.
The vanishing point is the inclination axis.