Before you shade anything, decide where the light comes from. Pick one light source, such as a window, a lamp or the sun, and keep it in the same place for the whole drawing.
Key idea
With one light, every lit side faces the light, and every shadow side and cast shadow points away from it.
Why it works
Light travels in straight lines from its source. Surfaces turned toward it catch the light; surfaces turned away do not. An object also blocks light from the surface behind it, so its cast shadow falls on the side away from the light. When every object follows the same rule, the drawing feels like one real place.
Worked example: Which side?
The light comes from a window on the right. On which side of an apple is its shadow side, and which way does its cast shadow fall?
- The lit side faces the window, on the right.
- The shadow side is the side turned away: the left.
- The cast shadow also points away from the light: to the left.
Answer: Shadow side on the left; cast shadow to the left.
Common mistake
People shade each object on a different side, as if there were several suns. Before shading, draw a small arrow in the corner of the page that shows where the light comes from, and check every object against it.