I represent a simple perspective camera.

Instance variables:
position <B3DVector3> where the camera is located
target <B3DVector3> where the camera is aiming at
up <B3DVector3> what is considered to be 'up' on screen
perspective <B3DCameraPerspective> the actual camera perspective

	converting
	asMatrix4x4

	experimental
	changeDistanceBy: moveToFit: rotateBy:

	initialize
	from3DS: from:to:up: initialize setClippingPlanesFrom: setTargetFrom:

	rendering
	renderOn:

	accessing	top
	aspectRatio
	aspectRatio:
	direction
	direction:
	farDistance
	farDistance:
	fieldOfView
	fieldOfView:
	fov
	fov:
	nearDistance
	nearDistance:
	perspective
	perspective:
	position
	position:
	target
	target:
	up
	up:

	converting	top
	asMatrix4x4 calculate z vector

	experimental	top
	changeDistanceBy:
	moveToFit: Move the camera to fit the given scene. Experimental.
	rotateBy: Experimental -- rotate around the current up vector by angle degrees. Center at the target point.

	initialize	top
	from3DS: Initialize the receiver from a 3DS camera. Note: #near and #far are NOT clipping planes in 3DS!
	from:to:up:
	initialize
	setClippingPlanesFrom: Set the clipping planes from the given object
	setTargetFrom: Make the camera point at the given object

	rendering	top
	renderOn:

	instance creation	top
	from3DS:
	new Answer a new instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable.