Finally, the code for Scalingobjects . py requires updating. We will only want one cube for now, so any other objects can be removed thus:
.
objects_3d $=[]$
objects_2d $=[]$
cube $=$ Object ("Cube")
cube.add_component (Transform $((0,0,-5)))$
cube.add_component (Cube (GL_POLYGON,
"images/wall.tif"))
objects_3d.append (cube)
grid $=\operatorname{Object}($ "Grid")
grid.add_component (Transform $((0,0,-5)))$
In the code you copied from Vectors . py in step 2, you will notice there is a second cube called cube 2 added. All references to this can be removed to leave just one object and the grid.