Limit CameraPick to the CameraRange ??

I thought it was a nice problem, so I tried to figure it out. This routine imitates the CameraPick with a LinePick. It uses CameraPick to initialize, and later on, it interpolates these coords to use it on LinePick:

;setup graphics
Graphics3D 800, 600, 0, 2
SetBuffer BackBuffer()

;create camera
cam = CreateCamera()
;set far/near range
InitCoords(cam, 1, 1000)

MoveEntity cam, 0, 0, -15

;setup cubes
For i = 0 To 100

	cube = CreateCube()
	EntityColor cube, Rand(255), Rand(255), Rand(255)
	PositionEntity cube, Rnd(-10, 10), Rnd(-10, 10), Rnd(0, 10)
	EntityPickMode cube, 2
	
Next

;main loop
Repeat

	If KeyDown(203) Then MoveEntity cam, +0.1,  0, 0
	If KeyDown(205) Then MoveEntity cam, -0.1,  0, 0
	If KeyDown(200) Then MoveEntity cam,  0, -0.1, 0
	If KeyDown(208) Then MoveEntity cam,  0, +0.1, 0

	RenderWorld()

	CamPick cam, MouseX(), MouseY()
	Text 0, 0, PickedEntity()	

	Flip

Until KeyHit(1)

End

;-----------------------------------------------------------------------------------------------------
;												InitCoords()
;-----------------------------------------------------------------------------------------------------

Dim 	cx#(0, 0)
Dim 	cy#(0, 0)
Dim 	cz#(0, 0)

Function InitCoords(cam, near#, far#)

	;to store points
	Dim cx#(1, 1)
	Dim cy#(1, 1)
	Dim cz#(1, 1)

	;set camerarange
	CameraRange cam, near#, far# + 1

	;create picking plane	
	plane = CreatePlane(1, cam)
	PositionEntity plane, 0, 0, 0
	RotateEntity plane, -90, 0, 0
	EntityPickMode plane, 2

	;place plane near
	PositionEntity plane, 0, 0, near#

	;pick upperleft corner	
	CameraPick cam, 0, 0
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cx(0, 0) = TFormedX()
	cy(0, 0) = TFormedY()
	cz(0, 0) = TFormedZ()

	;pick right corner
	CameraPick cam, GraphicsWidth(), 0
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cx(0, 1) = TFormedX()

	;pick bottom corner
	CameraPick cam, 0, GraphicsHeight()
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cy(0, 1) = TFormedY()

	;place plane far	
	PositionEntity plane, 0, 0, far#

	;pick upperleft corner	
	CameraPick cam, 0, 0
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cx(1, 0) = TFormedX()
	cy(1, 0) = TFormedY()
	cz(1, 0) = TFormedZ()

	;pick right corner
	CameraPick cam, GraphicsWidth(), 0
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cx(1, 1) = TFormedX()

	;pick bottom corner	
	CameraPick cam, 0, GraphicsHeight()
	TFormPoint PickedX(), PickedY(), PickedZ(), 0, cam
	cy(1, 1) = TFormedY()

	;free temp. plane
	FreeEntity plane

	;set camerarange
	CameraRange cam, near#, far#
	
End Function

;-----------------------------------------------------------------------------------------------------
;											CamPick()
;-----------------------------------------------------------------------------------------------------
Function CamPick(cam, x, y)

	;convert x/y in range 0..1
	px2# = x / Float(GraphicsWidth())
	py2# = y / Float(GraphicsHeight())
	px# = 1 - px2
	py# = 1 - py2
	
	;convert to near 'corner' coordinates (from initcoords)
	x1# = (cx(0, 0) * px + cx(0, 1) * px2)
	y1# = (cy(0, 0) * py + cy(0, 1) * py2)
	z1# = cz(0, 0)
	
	;convert to far 'corner' coordinates (from initcoords)
	x2# = (cx(1, 0) * px + cx(1, 1) * px2)
	y2# = (cy(1, 0) * py + cy(1, 1) * py2)
	z2# = cz(1, 0)	

	;convert to current cameraposition		
	TFormPoint x1, y1, z1, cam, 0
	x1# = TFormedX()
	y1# = TFormedY()
	z1# = TFormedZ()
	TFormPoint x2, y2, z2, cam, 0
	x2# = TFormedX()
	y2# = TFormedY()
	z2# = TFormedZ()

	;perform linepick
	LinePick x1, y1, z1, x2 - x1, y2 - y1, z2 - z1

	;debug preview dots
	Color 255, 0, 0 ;near=red
	CameraProject cam, x1, y1, z1
	Oval ProjectedX() - 5, ProjectedY() - 5, 11, 11
	Color 255, 255, 255	;far=white
	CameraProject cam, x2, y2, z2
	Oval ProjectedX() - 2, ProjectedY() - 2, 5, 5
			
End Function

And if you want to adjust the far/near variables realtime, you could interpolate between the start and end point of the picking line.