Shapes are used mainly in colliders to define the over all shape of a collider. Shapes can though also be used for Debug Drawers which allows to display physics structures easily. Shapes are analytical geometry and always convex. Combining shapes is always an union. Hence combined shapes can very well be concave but not the individual shapes itself.

A sphere is defined by a position and a radius. Ellipsoids are not supported by this shape only true spheres.

A box is defined by a position, orientation and the half length of the extends.

A cylinder is defined by a position, orientation, half height and twwo radi. The cylinder is centered around the position and has the major axis point upwards along the Y-Axis. The half height indicates half the length of the cylinder ( from the top face to the bottom face ). The top and bottom radius indicate the radius of the top and bottom face circle. If both are the same the cylinder is a common cylinder otherwise it is a tapered cylinder.

A capsule is defined by a position, orientation, half height and two radi. The capsule is centered around the position and has the major axis point upwards along the Y-Axis. The half height indicates half the length of the capsule ( from the top sphere to the bottom sphere ). The top and bottom radius indicate the radius of the top and bottom sphere. If both are the same the capsule is a common capsule otherwise it is a tapered capsule.

A convex hull is defined by a position, orientation, and a list of points. The hull shape is defined as the convex hull wrapping all points. Think of it like wrapping the points into a gift paper.