Cast shadows (direction, softness)
Shaping cast shadows so their direction, length, and softness match the light source and describe the forms that cast them.
What it is
Cast shadows are the shapes an object throws onto other surfaces when it blocks light — a character's shadow on the floor, a nose shadow on the cheek, a tree's shadow across a road. You choose where that shape lands, how long it is, and which forms it climbs over, based on where the light comes from.
Direction comes first. For any point on the casting object, imagine a straight line from the light source through that point, extended until it hits another surface. Connecting those hits gives the shadow its shape. This is why every shadow from a single sun angle leans the same way, and why a vertical pole in low sunlight throws a long shadow along the ground.
Softness is about edges. A small, distant light, like midday sun, gives hard-edged cast shadows. A large or nearby light, like an overcast sky, a softbox, or a window, gives softer, blurrier edges, especially farther from the object. In practice, you vary edge sharpness along one shadow: harder near the contact point, softer as it stretches away.
As you paint, treat cast shadows as design elements, not afterthoughts. Simplify busy shapes, keep some edges sharp for clarity, and let others soften or break. Respect the surfaces they fall on: shadows wrap over curves, bend at corners, and change scale and direction crossing from floor to wall or object to object.
Why it matters
If cast shadows ignore the light's direction or softness, the image falls apart: objects look pasted on, figures float instead of touching the ground, and forms stop reading where shadows cross them. Uniform edge softness, or shadows that bend the wrong way over a plane, feel wrong even when the viewer can't say why. Get it right, and cast shadows lock objects into the scene, clarify spatial relationships, and set the time of day and mood.
You can check it when
- ✓You can pick a light direction and place every cast shadow in the scene so it leans and stretches consistently with that choice.
- ✓Your cast shadow edges vary in softness believably: sharp near the contact point, softer with distance or under larger light sources.
- ✓Your cast shadows change shape correctly when crossing a corner or curved form, instead of sliding across as if the surface were flat.
- ✓Your characters and props feel grounded and attached to the environment rather than floating, because their cast shadows sit in the right place and shape.