Rotating groups of objects?

framework brl.glmax2d
	
Type position
	Global rootlist:Tlist

	Field x:Float=0.0,y:Float=0.0
	Field radius:Float=0.0,angle:Float=0.0
	Field root:position=Null,parent:position=Null
	Field child:Tlist = CreateList()
	
	Function Create:position(x:Float,y:Float,parent:position=Null)
		'create a new position object and attatch it to the correct list
		Local position:position = New position
		
		'setup
		position.x = x
		position.y = y
		
		'check if this position should be parented to another position
		If parent <> Null
			'insert into parent child list
			ListAddLast(parent.child,position)
			'set parent link
			position.parent = parent
			'set root link
			position.root = parent.root
			'calulate initial angle and raidus of child
			position.CalculateVector()
		Else
			'insert into global list
			ListAddLast(position.rootlist,position)
			'set root link to self
			position.root = position
		End If
		
		'return created position
		Return position
	End Function
	
	Method New()
		'check to see if rootlist needs to be initiated
		If position.rootlist = Null position.rootlist = CreateList()
	End Method
	
	Method Turn(angle:Float)
		For Local child:position = EachIn Self.child
			child.angle:+angle
			child.x = Self.x+Cos(child.angle)*child.radius
			child.y = Self.y+Sin(child.angle)*child.radius
			child.Turn(angle)
		Next
	End Method
	
	Method Update()
		'update for this position
		If Self.parent DrawLine Self.x,Self.y,Self.parent.x,Self.parent.y
		DrawOval Self.x-5,Self.y-5,10,10
		'update children of position
		For Local child:position = EachIn Self.child
			child.Update()
		Next
	End Method
	
	Method CalculateVector()
		'calculate radius and angle based on parent -> self offset
		Self.angle:Float = ATan2(Self.y-Self.parent.y,Self.x-Self.parent.x)
		If Self.angle < 0 Self.angle = 360:Float + Self.angle
		Self.radius:Float = Sqr((Self.x-Self.parent.x)^2 + (Self.y-Self.parent.y)^2)
	End Method
End Type

Graphics 640,480,32,60

parent:position = position.create(320,240)
	child1:position = position.create(320,140,parent)
		child1ofchild1:position = position.create(320,90,child1)
		child2ofchild1:position = position.create(270,140,child1)
		child3ofchild1:position = position.create(370,140,child1)
		child4ofchild1:position = position.create(320,190,child1)
	child2:position = position.create(220,240,parent)
		child1ofchild2:position = position.create(220,190,child2)
		child2ofchild2:position = position.create(170,240,child2)
		child3ofchild2:position = position.create(270,240,child2)
		child4ofchild2:position = position.create(220,290,child2)
	child3:position = position.create(420,240,parent)
		child1ofchild3:position = position.create(420,190,child3)
		child2ofchild3:position = position.create(370,240,child3)
		child3ofchild3:position = position.create(470,240,child3)
		child4ofchild3:position = position.create(420,290,child3)
	child4:position = position.create(320,340,parent)
		child1ofchild4:position = position.create(320,290,child4)
		child2ofchild4:position = position.create(270,340,child4)
		child3ofchild4:position = position.create(370,340,child4)
		child4ofchild4:position = position.create(320,390,child4)

While KeyHit(KEY_ESCAPE) = False
	Cls
	parent.Turn(1)
	child1.Turn(-2)
	child2.Turn(-2)
	child3.Turn(-2)
	child4.Turn(-2)
	parent.Update()
	Flip
Wend