#12 unimplemented basic obstacle shapes, unify shape code

[Craig Reynolds]

Several obvious basic obstacle shapes are missing and should be implemented, see details below. More generally, procedural shapes are used independently in several parts of PSCrowd. An effort should be made to unify this "shape describing" code and then use this shared shape library for describing the shape of obstacles, paths, surfaces and vehicle body shapes for non-penetration constraints.

It would be nice if we supported importing shape geometry in some interchange format (possibly Collada?: http://www.collada.org/ ) and then being able to use it as a standard shape for purposes of obstacle avoidance, or defining a surface on which vehicles can move.

(see also related discussion at: https://sourceforge.net/forum/message.php?msg_id=4154544 )

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The current menagerie of obstacle shapes includes:

SphereObstacle
BoxObstacle
PlaneObstacle
RectangleObstacle

there is a To Do list here: http://sourceforge.net/forum/message.php?msg_id=2839263
which I have slightly updated below:

3D/Volumetric:

SphereObstacle [done]
BoxObstacle [done]
CylinderObstacle
CapsuleObstacle
ConeSphereObstacle
PrismObstacle
MeshObstacle
FrustumObstacle

Planar (but embedded in 3d space)

RectangleObstacle [done]
PlaneObstacle [done]
TriangleObstacle
DiskObstacle
PolygonObstacle