« back to class 6 » Highlights » Cylinders » Vents/Ribs » Buttons Basic rule: »The part casting the shadow protrudes from the surface with the shadow cast on it. »Shadows are a darker version of the base color of the product--not necessarily black Angled Surface Basic rule: »surfaces angled toward the light are lighter than the front surface. »surfaces angled away from the light are darker than the front surface