The Basic 3D Forms

Shapes are flat. Forms have volume: height, width and depth. The leap from shape to form is the leap from a flat drawing to one that feels like you could pick it up. Four basic forms are enough to build almost anything.

The four basic forms

• Cube (box): the flat circle's cousin is the square; the square's 3D version is the cube. Buildings, furniture, books, heads, torsos and cars start as boxes.
• Sphere: the 3D circle. Fruit, eyes, heads, joints.
• Cylinder: a circle extruded along an axis. Arms, legs, cups, bottles, tree trunks, fingers.
• Cone: a circle that narrows to a point. Noses, party hats, horns, carrots, the tip of a pencil.

Drawing a box

A box has three visible faces when you see it from a corner. Key points:

• Parallel edges in reality stay visually consistent: they either stay parallel or converge toward the same point (we'll learn exactly how in the perspective module).
• The front corner is usually the closest point: it's often the longest vertical edge.
• Draw through the form: lightly sketch the hidden back edges too. It helps you check that the box is believable.

Drawing a sphere

A sphere is a circle that gets its volume from shading and contour lines. Draw an ellipse across it (like an equator) to suggest its tilt and orientation.

Drawing a cylinder

Draw the central axis first. Then draw two ellipses with their minor axis on that line (remember the minor axis trick). Connect the ellipses with two straight lines tangent to their outer edges. The ellipse closer to your eye level is thinner.

Drawing a cone

Draw an ellipse for the base and a point on its axis for the tip. Connect the tip to the ellipse with two tangent lines. Don't connect to the ends of the ellipse's major axis unless you're looking straight from the side.

Light makes the form

The same circle can be a flat disc or a sphere, depending on how you shade it. Play with the light below and watch how the forms turn:

We'll study light in depth in the light module. For now, notice that each form has a characteristic pattern: boxes have flat planes with distinct values, spheres and cylinders have smooth gradients.