By
adding a few lines we can shade the sphere. For all of the shapes we
shade the right side because the light comes from the left side. We can
do it the other way but in unison, either all on the left or all on the
right.
Now
lets continue shading the cube: be careful when adding the shadows, it
is very easy to ruin your drawing. Shade the whole base in the same
direction as the light.
