ChipmunkShapes:

Chipmunk2D for Unity has four primitive shapes, circles, rounded segments, boxes, and polygons. Shapes give a physical form to a ChipmunkBody, and define the actual area to interact with.

If a ChipmunkShape is not attached to a ChipmunkBody (on the same gameobject or a child of a ChipmunkBody). It is called a static shape. Static shapes don't move, but use less CPU and are ideal for things like terrain.

As with PhysX, you can attach multiple shapes to one body. Place additional shapes in children gameobjects. If you ever want two shapes inseparably bound together, this is the way to do it! (no joints needed!)

Inspector Values

• Friction - Higher friction means more force is required to slide this object against another. Friction can be any value above 0, and a good starting point is around 0.7.
• Elasticity - Elasticity of 1.0 means a perfect bounce with no loss of energy. Elasticity of 0.0 means a completely inelastic collision. Typically you'll want to keep this under 1.0 (rounding issues may cause energy to be added to the system), and in most cases, zero.
• isSensor - Sensors don't generate collisions, but they will call collision handlers.
• CollisionType - Collision Types are used in the names of collision callbacks. If you set the collision type of one shape to "player" and another shape to "oneway", the collision handler method "ChipmunkPreSolve_player_oneway" will be used. See the one-way platform guide for an example, or see the API docs.
• CollisionGroup - Shapes in the same group won't collide. This is an easy and flexible way to group composite objects that can intersect but shouldn't interact. For example, the included vehicle demo puts the wheels and chassis in the same group. In the event of extremely rough terrain, the vehicle wheels won't collide with the inside of the wheelwell, which would cause the wheel to stop.
  In addition, advanced users may use layers for fine-grained control over which objects collide.

The shapes

ChipmunkCircles are simulated as perfectly round shapes. They have a radius and center offset.

Pretty simple!

ChipmunkSegmentShapes are a line between two points, of a certain radius. Endpoints are independently adjustable in the editor. While creating segments with a radius of zero is fine, using a radius is recommended. Rounded edges help to prevent catching, especially when segments are used as terrain.

ChipmunkBoxShapes are a convenient way of creating a box. The editor supports easy size adjustments. You may supply a radius to bevel the edges of the box, if desired. Boxes are implemented as subclasses of ChipmunkPolygonShapes.

ChipmunkPolygonShape are arbitrary convex shapes defined by a series of vertices. You may bevel their corners by adjusting the radius.